science experiment on law of motion

Exploring the Science of Motion: 5 Simple and Fun Experiments for Kids

Activities » Science » Exploring the Science of Motion: 5 Simple and Fun Experiments for Kids

SHARE THIS POST:

Motion is all around us, from the gentle swaying of a tree branch to the roaring power of a race car. It’s a fascinating subject that has captured the imagination of scientists and curious minds alike.

Whether you’re a parent looking for fun and educational activities to do with your kids or an adult who wants to explore the science of motion in a hands-on way, these five simple experiments are sure to delight and inspire.

From creating your own mini rollercoaster to investigating the physics of pendulums, each experiment is designed to be both fun and informative. So grab some materials, roll up your sleeves, and get ready to discover the science of motion in a whole new way!

Newton’s Laws fascinate kids! You’re in for a treat! Science seems almost too good to be true. Even for us adults. Science across the board is not only amazing but can be performed or observed easily and inexpensively.

Remember when we learned about electricity ? How about our friction experiment ? Engaging kids in science seems straightforward, but what if you don’t ignite the sense of awe and wonder of the world?

5 Simple and Fun Experiments for Newton’s Laws of Motion

Experiment 1: balloon rocket.

For this experiment, you will need a long piece of string, a drinking straw, a balloon, and some tape. Cut a piece of string about 5 feet long and tie one end to a chair or doorknob.

Thread the straw onto the other end of the string and tape it in place. Blow up the balloon and pinch the end to keep the air inside. Tape the balloon to the straw and let it go.

The air rushing out of the balloon will propel the straw and create a “rocket” effect.

This experiment demonstrates Newton’s Third Law of Motion, which states that for every action, there is an equal and opposite reaction. When the air rushes out of the balloon, it creates a force that propels the straw in the opposite direction.

You can make the experiment more challenging by adding obstacles for the balloon rocket to navigate around or by using different sizes and shapes of balloons.

Experiment 2: Egg Drop Challenge

For this experiment, you will need an egg, some materials for padding, and a place to drop the egg from. The challenge is to create a protective casing for the egg that will prevent it from breaking when it hits the ground.

You can use materials like cotton balls, bubble wrap, or foam to cushion the egg. Once you’ve created your casing, drop it from different heights and see if the egg survives.

This experiment demonstrates the concept of inertia, which is the tendency of an object to resist changes in its motion. When the egg is dropped, it has a certain amount of kinetic energy that is converted into potential energy as it reaches its highest point.

As the egg falls, the potential energy is converted back into kinetic energy, which causes it to accelerate. The padding around the egg helps to absorb some of the force of the impact and protect it from breaking.

I love this example of the project from Kiwi Co !

Experiment 3: Paper Airplane Race

For this experiment, you will need some paper and some creativity. Fold a piece of paper into an airplane and see how far it can fly. Experiment with different designs and techniques to see which one flies the farthest. You can also have a race with friends to see whose airplane can fly the fastest.

This experiment demonstrates the principles of aerodynamics, which is the study of how objects move through the air. The shape and design of the paper airplane can affect how it flies, with factors like lift, drag, and thrust all playing a role in its performance. By experimenting with different designs, you can learn more about the science of flight.

Experiment 4: DIY Wind Turbine

For this experiment, you will need some basic materials like a plastic bottle, a small motor, and some blades. Cut the top off the bottle and attach the blades to the motor. Place the motor inside the bottle and secure it in place. When the blades are turned by the wind, they will generate electricity that can power small devices like a lightbulb or a fan.

This experiment demonstrates the concept of energy conversion, which is the process of changing one form of energy into another. The kinetic energy of the wind is converted into electrical energy through the rotation of the blades. By experimenting with different blade designs and wind speeds, you can learn more about the science of renewable energy.

Experiment 5: Pendulum Painting

For this experiment, you will need a pendulum (which can be made by tying a weight to a string), some paper, and some paint. Hang the pendulum from a fixed point and place a piece of paper underneath it. Dip the weight into the paint and let it swing back and forth, creating a unique pattern on the paper.

This experiment demonstrates the principles of motion and gravity, with the pendulum swinging back and forth in a predictable pattern. The paint adds an artistic element to the experiment, creating a visual representation of the motion of the pendulum. You can experiment with different colors and weights to create different patterns and designs.

Generation Genius has a wonderful tutorial on pendulum painting with kids .

Newton’s Laws for Kids Must Try Activity

In the meantime, onto our Newton’s Laws of Motion (the 3rd law to be specific) experiment! Every month we receive Steve Spangler’s Science Club Kit . Steve’s Kit is superior and full of amazing experiments, science learning for kids, and a Top Secret guide for parents and teachers. The experiments build (scaffolding) upon each other so kids really get the science. Extremely well done.

The Helicopter Balloon is one super fun way to introduce kids to more complex scientific ideas.

The kit we received includes three blades, a blade connector, a hub, and two balloons. A bit tricky for a younger child to put together but my 6.5-year-old was able to make it happen. The key is after the balloon is blown up, to pinch the balloon as you attach it to the hub, and wait for the amazing science.

Explanation of the Science Behind Each Experiment

Each of these experiments demonstrates different principles of motion and physics.

The balloon rocket experiment shows Newton’s Third Law of Motion, which states that for every action, there is an equal and opposite reaction. The gas coming from the balloon forces the blades to rotate, the blades drive the air down to cause the helicopter to lift. Kids love this activity.

The egg drop challenge demonstrates the concept of inertia, which is the tendency of an object to resist changes in its motion.

The paper airplane race demonstrates the principles of aerodynamics, which is the study of how objects move through the air.

The DIY wind turbine experiment demonstrates the concept of energy conversion, which is the process of changing one form of energy into another.

The pendulum painting experiment demonstrates the principles of motion and gravity.

You can buy the Toysmith Balloon Helicopter kit on your own from Amazon or you can subscribe to Steve Spangler’s Science Club , which I highly recommend.

What if your child has no desire to learn more? I thought about that a while back. If this obstacle sounds familiar check out a post I wrote on Ways to Help a Child with Science Thinking . Let me know what you think.

Related Reads

• Easy Motion Science Experiment that Will Wow Your Kids
• 10 Creative & Unique Easter Basket Ideas for Boys
• Brighten Up Your Kid’s Day with these Fun and Educational Light Activities
• Super Easy, Fun, & Unforgettable Water Balloon Activities for Kids
• Why Should Parents Care about Emotional Intelligence?
• Easy Physics Experiment for Kids

This site uses Akismet to reduce spam. Learn how your comment data is processed .

CONSIDER YOUR WEEKENDS PLANNED!

Get the best Metro Family events, festivals, concerts and activities for families delivered straight to your inbox.

• Our Magazines

Where OKC parents find fun & resources

• Get our newsletter

Simple Science Experiments: Newton’s First Law of Motion

by Steve Davala

Many years ago, Sir Isaac Newton came up with some most excellent descriptions about motion. His First Law of Motion is as follows: “An object at rest stays at rest and an object in motion stays in motion unless acted upon by an outside force.” Quite a mouthful. What that means is that something that is sitting there will continue to sit there unless moved. And something moving will keep moving unless something stops it.

Still a mouthful. Just think about this: When you are at a stoplight in your car and you start moving quickly, you feel pushed back into your chair. The opposite is true if you come to a sudden stop, and you move keep moving forward, with only your seatbelt preventing you from crashing forward.

Here are a couple of experiments that demonstrate this very cool law of motion; in a word called “inertia.”

Ball Bounce Experiment

Materials for the Ball Bounce Experiment:

• A basketball or soccer ball, or similar bouncy ball
• a smaller bouncy ball (like a tennis ball or a racquet ball).
• Have an assortment of other balls handy for further experimenting.
• Do this experiment outside
• First bounce the basketball and tennis ball side by side to compare their bounces. Start them off around chest height
• Make a hypothesis (a guess) about what will happen when you stack the small ball on top of the bigger one and then drop it
• Try it! It may take a couple tries to line them up just right but the results are pretty awesome

Explanation:

The energy of motion from the bigger ball is transferred into the smaller one. Most of your attention is on the sky-rocketing smaller ball, but if you look at the basketball, it doesn’t have much bounce at all!

Experiment further:

Hopefully this will make you think of other things. Like what if you switched the two balls and dropped the smaller one on the bottom? What if you used two of the same sized ball? A golf ball on top? Think of other things!

Penny on a Card Experiment

Materials for the Penny on the Card Experiment:

• a small plastic cup,
• a playing card

Procedure :

• Put a playing card on top of the plastic cup
• Put a coin on top of the card
• With a sharp flick, hit the card out from under the coin! Or pull it really quickly toward you.
• The coin will drop into the cup.

The coin has inertia, meaning it really wants to stay in one place. If you move the card slowly, it isn’t fast enough to overcome that force. If you flick it quickly, the coin stays in one place and then drops into the cup. An object at rest will remain at rest. If you are brave, put the card on your finger and the coin on top… try to flick the card out until the coin stays on your finger. It can be done!

Use a sheet of printer paper with a few heavier (non-breakable) objects on it. See if you can quickly pull the paper out from under the objects.

Another cool example of inertia: Put your hand, palm side up, next to your ear. Put a coin on your elbow. In one swift motion, bring your hand straight forward and try to catch the coin before it drops. If you’re fast (and lucky) enough, you will catch the coin before gravity has a chance to bring it down.

I hope you enjoyed this simple experiment and learned a little bit about the first law of motion and inertia. If you have more questions about this, or need tips about science fair ideas around this topic (or others), feel free to contact me.

Steve Davala is a middle school science teacher who likes to write. He’s got two kids of his own and subjects them to these science activities as guinea pigs. Follow him on Twitter or email him at [email protected] .

more stories

Homework Help at the Pioneer Library

Story Times in the OKC Metro

Fun, free events at Metropolitan Libraries this month

Popular articles, featured events.

• 1 MetroFamily’s Cover Kids Search
• 2 MiracleCon – Extra Life Gaming Convention
• 3 FREE Rock the Route
• 4 FREE Brown Bag-it with Banjos at American Banjo Museum
• 5 FREE Uptown Outside
• 6 AT&T Sunday Fun Day at FAM
• 7 Wings Annual Fall Festival and Pumpkin Patch
• 8 Down Syndrome Festival and 5K

Follow Us on Instagram!

• Find the Magazine
• Back Issues

Engage With Us

• Signature Events
• Submit an Event

Things to Do

• Calendar of Events
• Seasonal Fun
• Weekend Picks
• Exploring Oklahoma
• Local Resource Guides
• Family Favorites
• Local Blogs

Copyright 2024 Metro Family Magazine. All rights reserved. | Terms of Use | Privacy Policy | Powered by WEB PUBLISHER PRO

Privacy Overview

Science Fun

Force And Motion Science Experiments

Easy motion science experiments you can do at home! Click on the experiment image or the view experiment link below for each experiment on this page to see the materials needed and procedure. Have fun trying these experiments at home or use them for SCIENCE FAIR PROJECT IDEAS.

Strength Test:

Magic Ball:

Observe Centrifugal Force In Action

Can A Light Weight Lift A Heavy Weight?:

Coin In A Cup:

Observing Inertia:

Coin Flick:

Magically Remove The Bottom Coin

Hammer Head:

Seemingly Defy Gravity

Galileo’s Swinging Strings:

Use Straws To Reduce Friction:

Find A Hard Boiled Egg:

Use Spinning Science In This Experiment

Unbreakable Thread:

Magic Napkin:

Cotton Ball Catapult:

Rapid Rubber Band Launcher:

Send A Bunch Of Rubber Bands Flying

Water Balloon Physics:

Centrifugal Force: 

Stab A Potato:

Traveling Toothpicks:

Surface Tension And Toothpicks Do Mix

Balance A House On Your Finger:

Ruler Race:

Easy Film Canister Rocket:

Rocket Balloon Blast:

This Balloon Really Moves

Mini Marshmallow Launcher:

Build Your Own Balance Buddy:

• Earth Science
• Physics & Engineering
• Science Kits
• Microscopes
• Science Curriculum and Kits
• About Home Science Tools

Science Projects > Physics & Engineering Projects > Newton’s Laws of Motion & Projects  

Newton’s Laws of Motion & Projects

Sir Isaac Newton’s laws of motion form the basic principles of modern physics . When published in 1687, the three laws were unique in that they used mathematical formulas to explain the natural world.

Newton’s Laws Defined

Inertia: newton’s first law of motion.

Newton’s First Law of Motion, also known as the Law of Inertia, states that an object’s velocity will not change unless it is acted on by an outside force.

This means that an object at rest will stay at rest until a force causes it to move.

Likewise, an object in motion will stay in motion until a force acts on it and causes its velocity to change.

For further thought : Why do wheels and tops eventually stop spinning, without appearing to be touched by a force?

Newton’s Second Law of Motion

Newton’s Second Law of Motion states that ‘when an object is acted on by an outside force, the strength of the force equals the mass of the object times the resulting acceleration’.

In other words, the formula to use in calculating force is force = mass x acceleration . Opposing forces such as friction can be added or subtracted from the total to find the amount of force that was really used in a situation.

You can demonstrate this principle by dropping a rock or marble and a wadded-up piece of paper at the same time. They fall at an equal rate—their acceleration is constant due to the force of gravity acting on them.

However, the rock has a much greater force of impact when it hits the ground, because of its greater mass. If you drop the two objects into a dish of sand or flour, you can see how different the force of impact for each object was, based on the crater made in the sand by each one.

Another way to show this is two push off two toy cars or roller skates of equal mass at the same time, giving one of them a harder push than the other. The mass is equal in both, but the acceleration is greater in the one that you exerted greater force on.

Newton’s Third Law of Motion

Stated simply, Newton’s Third Law of Motion says that ‘for every action, there is an equal and opposite reaction.’

Use a pair of roller skates and a ball to show how this works. What happens when you’re standing still in skates and then throw a ball hard? The force of throwing the ball pushes your skates (and you) in the other direction.

You can also demonstrate this using Newton’s Cradle .

This apparatus consists of steel balls suspended on a frame. When the ball on one end is pulled back and then let go, it swings into the other balls. The ball on the opposite end then swings up with an equal force to the first ball, as shown in the illustration on the right.

The force of the first ball causes and equal and opposite reaction in the ball at the other end.

For further thought : Thrust is an important result of Newton’s Third Law. How does this work in a rocket? Read more about rockets and rocketry .

Newton’s Laws Projects

• Check out our inertia apparatus to understand Newton’s First Law better.
• Check out our dynamic carts to gain a better understanding of Newton’s Second Law.
• Check out our Newton’s Cradle for a classic demonstration of Newton’s Third Law of Motion.

Physics & Engineering

Welcome! Read other Physics & Engineering related articles or explore our Resource Center, which consists of hundreds of free science articles!

Shop for Physics Supplies!

Home Science Tools offers a wide variety of Physics products and kits. Find physics & engineering tools, equipment, STEM kits & more for kids and adults.

Related Articles

Homopolar Motor – Make a Spinning Wire Sculpture

In this experiment, we will make a homopolar motor! To make a simple motor (homopolar motor) that doubles as a work of art you will need three things – a battery, magnet, and wire. Use one of our neodymium magnets to power the spinning wire motor. What You Will Need:...

Solar Energy Matching Game

Print out this page on a sheet of heavy paper or cardstock. Kids can color the pictures and cut out the squares to make a matching game. Half of the squares show a way to use solar energy as an alternative to the picture shown on the other squares. Place all the...

Simple Spring Break Science Projects

Spring break is here! What will you do with your time off? Perhaps you're looking forward to a family vacation, or a few days of down time at home. Either way, find a quick and easy project that's sure to put a sparkle in the eye of any science lover, or win over a...

Sink or Float Worksheet

Use the Sink or Float Worksheet with the "Sink or Float?" science project to encourage kids to make predictions, perform tests, and record their results. This project is perfect for indoor discovery - especially in colder months! Put a towel under a large container of...

Physics Science Fair Projects

Find physics science fair project ideas about magnetism, electricity, energy and solar power, and more.

JOIN OUR COMMUNITY

Get project ideas and special offers delivered to your inbox.

• Skip to primary navigation
• Skip to main content
• Skip to primary sidebar

Teaching Expertise

• Classroom Ideas
• Teacher’s Life
• Deals & Shopping
• Privacy Policy

Newtons Laws Of Motion Activities For Middle School: Ideas For First Law, Second Law, Third Law, Inertia, Motion, And Momentum

February 14, 2024 //  by  Cassie Caroll

There is no better way to teach your middle schooler about the laws of motion than by putting their knowledge into action. While Newton’s laws may seem a bit foreign to your learner at first, we found some of the best hands-on activities to help your student better understand these concepts. An object in motion stays in motion, and we hope these experiments will keep your learner learning! With some common objects and an inquisitive mind, we’ve found these exercises both engaging and enlightening!

Newton’s First Law Activities

1. ball bounce experiment.

One way to demonstrate Newton’s first law is by observing a ball in motion. Head to your garage and grab any type of ball you can find — a basketball, tennis ball, bouncy ball — the more varied the better. Then, have your student execute this activity to observe the different ways an object in motion reacts to outside forces. Consider keeping track of hypotheses and observations in a notebook!

Learn More: Metro Family Magazine

2. Inertia Demonstration

While inertia is a simple concept on the surface, putting the idea into action makes it much more accessible as the laws get more complex. This inertia demonstration allows your student to become the force that disrupts an inert object, plus it can quickly become a favorite “magic trick.”

Learn More: Science Sparks

3. Marble Maze

An object in motion stays in motion, and one way to manipulate the way in which an object moves is by constructing a marble maze. We like how easy this activity is to differentiate depending on your student’s level of understanding.

Learn More: Instructables

4. Inertia Hat

Do you know those pesky wire hangers that never seem to stay intact? Put them to good use with this inertia hat activity! Follow along with this video to experiment with the intricacies of inertia  and to give you and your student permission to get a little silly.

Learn More: Youtube

5. Quarter Catch

This activity will only cost 25 cents! The quarter catch is another experiment that may become a favorite party trick. Your student will place a quarter on their elbow and practice moving quickly enough to catch it before it falls, demonstrating inertia.

Learn More: Science Fun

6. Bernoulli’s Activity

Although this activity is based on Bernoulli’s principle, it has a direct correlation to Newton’s first law. Ask your student to figure out what happens when the force of their breath is applied to the ping pong ball and then when it is taken away. This is a great closure activity that quickly demonstrates the concept while making it fun!

Learn More: 123 Homeschool 4 Me

7. Whack-a-Stack

Like a quick game of Jenga, the whack-a-stack activity gives your student yet another example of Newton’s first law. All you need is a small stack of blocks or similar objects and a pipe-like instrument to conduct this experiment.

Learn More: Exploratorium

Newton’s Second Law Activities

8. marshmallow puff tube.

To explore acceleration and unbalanced forces, grab a marshmallow, some flour, a file folder, and a bit of tape. We love that this can be a very simple demonstration of Newton’s second law or be pushed even further to explore acceleration and friction.

9. Egg Bungee

To conceptualize different types of energy at play, have your student try this egg bungee experiment. You can use a range of materials to look at the roles of potential and kinetic energy, but don’t forget the paper towels for a swift clean up!

Learn More: Museum of Science+Industry Chicago

10. Crater Experiment

This crater experiment creates an excellent visual for Newton’s second law. The craters created by various items will help you demonstrate how mass and acceleration factor into an object’s force. This is another activity that will require some minor cleanup, but placing a towel underneath your experiment area can help.

11. Build a Projectile

Have your student learn about stored energy while creating a new toy  and recycling! This projectile activity is fun and informative and can be done using common household objects. Be sure to check out more instructions in the link.

Learn more: Arvin D. Gupta Toys

Newton’s Third Law Activities

12. popping canisters.

We love this Alka-Seltzer activity! With a little prep, this experiment can be a mess-free, interactive experience with Newton’s third law. This may take a couple of practice rounds, but the demonstration of equal and opposite reactions is well worth the rehearsal.

Learn More: Science Matters

13. Rocket Pinwheel

Bring the action-reaction principle to life with this DIY rocket pinwheel ! Using common household items and a dash of creativity, this rocket pinwheel can quickly become a favorite activity demonstrating Newton’s third law.

Learn More: NASA Teacher’s Resource Center

14. Hero’s Engine

To demonstrate Newton’s third law  and introduce your student to rocketry basics, try this Hero’s Engine activity. This activity can be done using different materials depending on what you have at your disposal. Try this pop can adaptation if you don’t have a plastic cup handy.

Learn More: Wabi 5

15. Marble Momentum 

You can demonstrate Newton’s third law in many different ways using just marbles! This particular marble experiment allows you to differentiate according to your students’ understanding and interest. Keep pushing your experimentation using a different number of marbles or even different sizes, then push it even further by using skateboards described later in these directions.

Learn More: Metro Family

16. Balloon Rocket

With just a string, straw, and latex balloon, your student can experiment with air flow and motion. Take a look at the balloon rocket activity shown at the start of this video. Then, discuss what your student is seeing. Why is it the balloon follows the trajectory they observed? How does air flow affect the balloon’s momentum?

17. DIY Newton’s Cradle

What’s a study of Newton’s law without Newton’s cradle? This super easy DIY Newton’s Cradle allows your student to take ownership over their learning and create a living example of Newton’s third law. There are tons of different ways of building a cradle, but we found this one to be the most user and budget friendly.

Learn More: Babble Dabble Do

More Inertia, Motion, and Momentum Activities

18. tablecloth pull.

Another fun way of experimenting with inertia is by practicing this “magic trick” with your learner. Our advice is to invest in some plasticware for this activity to avoid any broken glass. You may also want to opt for the wax paper alternative described in the post for optimal results.

Learn More: Science World

19. Collision Course

For a quick demonstration of equal and opposite reactions, create this miniature bumper car scenario! Grab two of anything that rolls of equal size. This collision course activity can be done as a brief demo or can be extended to be a more in-depth investigation of Newton’s third law.

Learn More: Science Buddies

20. Baking Soda Powered Boat

Create a baking soda-powered boat in your bathtub or nearby body of water! This experiment allows your learner to look at the different forces at work when their boat takes off.

21. Newton Car

Bring your student’s learning full circle by demonstrating all three of Newton’s laws using Newton’s car lab! This activity takes more time to setup, but the payoff is well worth it.

Learn More: NASA

22. Spinning Marbles

This spinning marbles activity is a great way to first introduce the idea of inertia and then experiment with different types of motion. Of course, be sure to supervise your learner when they use the hot glue!

Learn More: Kids Activities

23. Momentum Machine

Instead of creating a machine, why not become the machine yourself? Have your learner grab a spinning chair and a couple of liter bottles to experiment with momentum. This also creates a great boomerang moment for Instagram!

24. Spaghetti Accelerometer

If your learner is ready to consider acceleration when it comes to the laws of motion, this activity can be an excellent introduction. Although this spaghetti accelerometer requires some power tool work, once the setup is complete, it is a great opportunity to push your learner.

9 Engaging Newton's Laws of Motion Project Ideas

As a dedicated physics educator, you have the exciting task of introducing students to the laws of motion established by Sir Isaac Newton. Whether you're a seasoned teacher looking to refresh your curriculum or a newcomer eager for innovative teaching strategies, exploring Newton's Laws of Motion through a mix of hands-on and virtual labs offers a dynamic approach to learning.

We've identified six in-person labs and three virtual labs you can do with your students.

Newton's First Law Project Ideas

Sir Isaac Newton came up with some observations about motion. His First Law of Motion is: “An object at rest stays at rest, and an object in motion stays in motion unless acted upon by an outside force.”

Hands-on lab: Moving Cart

Simulate a car accident's impact using a moving cart to demonstrate the effects of inertia without a seatbelt. Set up a simple cart with two wheel axes and a mass, and crash it into a cardboard box. Tape the cardboard box to the floor and mark a starting point about 5 feet away. Vary the speed of the collision and observe how the mass moves forward on the cart at different distances and speeds. The mass remains in motion due to inertia, even though it abruptly stops upon hitting the cardboard. Record and discuss the observations, and optionally, tape the mass to the cart to simulate a seatbelt.

Virtual lab: Newton's First Law of Motion: Balanced and unbalanced forces

In Labster's Newton’s First Law of Motion simulation , students visually observe how different forces act on an object and how motion takes place when forces are unbalanced.  Students will travel back in time to where Newton is surprised to see them in his room. He is quite upset since while he was working under a tree, an apple fell on his head and made him forget his First Law of Motion. Luckily they'll be able to join him in 1687 and help him rediscover everything about his law.

Hands-on lab: Penny on a Card Experiment

The Penny on a Card science project explores Newton's First Law of Motion, or the law of inertia. By flicking or pulling an overhanging card, the card slides off the table while the penny stays in place. This hands-on experiment helps students understand the concept of inertia and encourages critical thinking and observation skills. 

Newton's Second Law Project Ideas

Newton's Second Law of Motion states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. In mathematical terms, this can be expressed as F = ma, where F represents the net force, m denotes the mass of the object, and a represents the acceleration. 

Hands-on lab: Egg Crush Experiment

This engaging project allows students to explore Newton's Second Law of Motion. Using only flat wooden toothpicks and wood glue, students are challenged to build a device capable of protecting an egg from being crushed by the force of a falling 5-gallon bucket. This hands-on activity also enhances their critical thinking and problem-solving skills. By considering concepts such as inertia, force, and reaction, students can design and construct an effective contraption and gain a practical understanding of the fundamental principles of motion.

Virtual lab: Newton's Second Law of Motion: Speed and Acceleration

In Labster's virtual lab , students travel through time and space to help Newton rediscover his Second Law of Motion. Students can use this physically realistic simulation to experiment with forces and masses and observe their effects on acceleration and velocity. Students will apply forces on a body with adjustable mass to control its acceleration and produce different kinds of motion. Includes experimentation tasks and directed challenges that require the student to take the effects of added forces into account or produce a specific motion. 

Hands-on lab: Toy Car Speed Project

For a Newton's Second Law of Motion project, you can conduct a toy car speed experiment. Create a ramp using books and meter sticks, and place different masses on the toy cars. Roll the cars down the ramp and record the time it takes for each one to reach the bottom. Manipulate the ramp height while keeping the mass constant to observe the impact on speed. Use the collected data to create a graph and write a paper explaining how the experiment aligns with Newton's Second Law. Explore how acceleration depends on net force, mass, and gravity's applied force. This project allows for a practical demonstration of Newton's Second Law and helps in understanding the relationship between height and speed.

Newton's Third Law Project Ideas

Newton's Third Law simply states that for every action, there is an equal and opposite reaction.

Hands-on lab: Newton's Cradle

The Newton's Cradle lab is a hands-on experiment that allows high school students to explore Newton's Third Law of Motion. Using a Newton's Cradle apparatus, students observe the conservation of momentum and energy in collisions. They pull back one ball, release it, and observe the transfer of energy to the other balls. By varying parameters like the number of balls or angle of release, students deepen their understanding of these principles. 

Virtual lab: Newton's Laws of Motion: Understand active and passive safety in motorsports

In this simulation , Labster uses Newton’s laws of motion to break down the passive and active safety features of a race car to enable our drivers to move faster in the safest way possible. In most interactions, there is a pair of forces acting on the two interacting objects. This is what Newton’s Third Law of Motion describes. Check out examples of this law in motorsports and identify the action and reaction forces while driving.

Hands-on lab: Balloon Rocket Experiment

Stretch a piece of string across the classroom and thread a straw onto it. Inflate a balloon without tying it off, tape it to the straw, and then release it. The air rushing out of the balloon propels it in the opposite direction, demonstrating Newton's Third Law.

Newton's Laws of Motion provide a fascinating framework for understanding the fundamental principles that govern how objects move in the physical world. By engaging in hands-on projects and virtual experiments related to these laws, students can deepen their understanding of concepts such as force, acceleration, and inertia. 

Applying Newton's Laws of Motion to real-life situations empowers students to develop critical thinking skills and gain a deeper appreciation for the laws that shape our world. Incorporating these project ideas can enhance the students learning journey and inspire a lifelong passion for science and discovery.

Labster helps universities and high schools enhance student success in STEM.

Explore More

Introducing Labster’s Back-to-School Physics Collection, Here to Make Teaching Easier

Introducing Labster’s Back-to-School Biology Collection, Here to Make Teaching Easier

Introducing Labster’s Back-to-School Chemistry Collection, Here to Make Teaching Easier

Discover The Most Immersive Digital Learning Platform.

Request a demo to discover how Labster helps high schools and universities enhance student success.

• Science Notes Posts
• Contact Science Notes
• Todd Helmenstine Biography
• Anne Helmenstine Biography
• Free Printable Periodic Tables (PDF and PNG)
• Periodic Table Wallpapers
• Interactive Periodic Table
• Periodic Table Posters
• Science Experiments for Kids
• How to Grow Crystals
• Chemistry Projects
• Fire and Flames Projects
• Holiday Science
• Chemistry Problems With Answers
• Physics Problems
• Unit Conversion Example Problems
• Chemistry Worksheets
• Biology Worksheets
• Periodic Table Worksheets
• Physical Science Worksheets
• Science Lab Worksheets
• My Amazon Books

Newton’s Laws of Motion

Newton’s laws of motion are three laws of classical mechanics that describe the relationship between the motion of an object and the forces acting upon it.

• A body in motion remains in motion or a body at rest remains at rest, unless acted upon by a force.
• Force equals mass times acceleration: F = m*a. Or, the rate of change of a body’s momentum equals the force acting upon it: F = Δp/Δt.
• For every action, there is an equal and opposite reaction.

Sir Isaac Newton describes the three laws of motion in his 1687 book Philosophiae Naturalis Principia Mathematica . The Principia also outlines the theory of gravity . While the Theory of Relativity applies to objects moving near the speed of light , Newton’s laws work well under ordinary conditions.

Newton’s First Law – Inertia

An object at rest remains at rest or an object in motion remains in motion at constant speed and in a straight line, unless acted upon by an unbalanced force.

Basically, the first law describes inertia, which is a body’s resistance to a change in its state of motion. If no net force acts on a body (all external forces cancel out), then the object maintains constant velocity. A motionless object has a velocity of zero, while a moving body has a non-zero velocity. An external force acting upon an object changes its velocity.

Here are some examples of Newton’s first law:

• A dropped ball continues falling
• If you let go of a moving cart, it continues rolling (ultimately stopped by friction)
• An apple resting on a table does not spontaneously move

Newton’s Second Law – Force

The rate of change of an object’s momentum equals the force acting upon it or the applied force equal’s an object’s mass times its acceleration.

The two equations for Newton’s second law are:

Here, F is the applied force, m is mass, a is acceleration, p is momentum, and t is time. Note that the second law tells us that an external force accelerates an object. The amount of acceleration is inversely proportional to its mass, so it’s harder to accelerate a heavier object than a lighter one. The second law assumes an object has constant mass (which is not always the case in relativistic physics).

Here are examples of Newton’s second law:

• It takes more effort moving a heavy box than a light one.
• A truck takes longer to stop than a car.
• It hurts more getting hit with a fast-moving baseball than a slow one. Each ball has the same mass, but the force depends on the acceleration.

Newton’s Third Law – Action and Reaction

When one object exerts a force on a second object, the second object exerts and equal and opposite force on the first object.

For every action, there is an equal and opposite reaction. So, if set an apple on a table, the table pushes up on the apple with a force equal to the mass of the apple times the acceleration due to gravity. This can be difficult to visualize, but there are more obvious examples of Newton’s third law:

• If you are wearing roller skates and you push another person wearing skates, you both move.
• A jet engine produces thrust. As the hot gases exit the engine, an equal force pushes the jet forward.
• Halliday, David; Krane, Kenneth S.; Resnick, Robert (2001). Physics Volume 1 (5th ed.). Wiley. ISBN 978-0471320579.
• Knight, Randall D. (2008). Physics for Scientists and Engineers: A Strategic Approach (2nd ed.). Addison-Wesley. ISBN 978-0805327366.
• Plastino, Angel R.; Muzzio, Juan C. (1992). “On the use and abuse of Newton’s second law for variable mass problems”. Celestial Mechanics and Dynamical Astronomy . 53 (3): 227–232. doi: 10.1007/BF00052611
• Thornton, Stephen T.; Marion, Jerry B. (2004). Classical Dynamics of P articles and Systems (5th ed.). Brooke Cole. ISBN 0-534-40896-6.

Related Posts

Newton’s Laws Experiment

This post may contain affiliate links.

I have a little lesson on Isaac Newton’s Laws of Motion today.  Plus a cool experiment to go along with it called Gravity Beads.

We get the Steve Spangler Science kits in the mail each month. Its a happy mail day when they come. They are a great addition to our science lessons and my kids just have so much fun with them.  (Not a sponsored post, just something we really love.) This month’s box was all about inertia and Newton’s laws of motion. Cool stuff.  The ultimate favorite of this month’s kit were the gravity beads. But first, a little refresher on motion & gravity for you!

What are Newton’s Laws of Motion & Gravity?

Newton’s First Law states that an object at rest will remain at rest and an object in motion will remain in motion (unless acted upon by force). Another important term is Inertia.   Inertia is the tendency of a body to resist a change in motion or rest.

Newton’s Second Law states that force is equal to the mass of the object times its acceleration or F= MA.  A force is a push or a pull, and mass is a measurement of the amount of matter the object has. Acceleration measures how fast the velocity (speed with direction) changes.  Sobasically it means that you need a force to move an object. The bigger the mass, the greater the force you will need.

Newton’s Third Law says that for every action there is an equal and opposite reaction. Simple? kinda.

Newton’s Law of Gravity says that every particle attracts every other particle in the universe with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers. Hu?

Simpler terms: Gravity is a force that tries to pull two objects toward each other. Anything which has mass also has a gravitational pull equal to its mass. The more mass an object has, the stronger its gravitational pull is. Gravity is what keeps you on the ground and what makes things to fall to the ground.

How to Do the Gravity Bead Experiment

Watch to see what it is first. 🙂

So, now that you have a basic grasp of Newton’s laws, (you probably already learned all of this in your physics class in high school right?) you will better be bale to understand how this gravity bead experiment works. It’s crazy cool and really just looks like magic, but it’s physics! This is all based on Inertia and the laws of motion!

All you need is a long strand of beads and a large cup. Really, that’s it!  These beads are like the cheap plastic Mardi Gras ones. You can get them anywhere. BUT, the difference here is the length of the strand. This strand is about 50 feet long. If you are going for cost effective, you could try to make our own with the regular beads- just glue many strands together. I am not sure whether it would really be cheaper or not, though.  If you are going for ease, pick up this long strand already done for you.

Since posting this, I have seen a lot of people say they see this happen with their Christmas bead garlands!  So here is a bead garland that is 26 ft. long . Or maybe you have some at home already?!

It’s best to use a large clear cup or glass so you can watch the process. Put the beads into the cup in circular rows so they do not get tangled up while coming back out. This is really important!

Leave the end of the strand hanging hanging out of the top of the cup.  If you make your own beads you will want to do something to distinguish the ends from the other parts of the strands- add a piece of tape to make it easy to find the ends.

When you are ready, give the strand of beads a little tug. Hold the cup high off the ground, so there is more of a pull downward. They will literally start moving and continue moving until the beads run out.

The coolest thing to do is to take a video of it in slow motion so you can really see what the movements look like.  You’ll see in our video that the beads move upward in an arc before going down. This is because of the initial pull you give it. It continues in that upward motion until the force of gravity brings it downward.  Awesome, right?!

Here’s a tip : Let the beads collect into another cup, then you can keep it going again and again!

Let us know if you try it out!

Want another cool gravity experiment?

Try this Gravity Spinner !

Or try one of my many other STEM projects for kids!

Former school teacher turned homeschool mom of 4 kids. Loves creating awesome hands-on creative learning ideas to make learning engaging and memorable for all kids!

Similar Posts

Shark Activities for Kids

New Year Activities For Kids

20 music apps for kids.

Color and Light Experiments with a Light Box

Jack and the Beanstalk Upper and Lower Case Letters

Edible Frog Life Cycle Snack

We inadvertently do this experiment every Christmas, when our bead garland leaps out of its cylindrical container ! Love it!

Leave a Reply Cancel reply

You must be logged in to post a comment.

• Skip to primary navigation
• Skip to main content
• Skip to primary sidebar

• FREE Experiments
• Kitchen Science
• Climate Change
• Egg Experiments
• Fairy Tale Science
• Edible Science
• Human Health
• Inspirational Women
• Forces and Motion
• Science Fair Projects
• STEM Challenges
• Science Sparks Books
• Contact Science Sparks
• Science Resources for Home and School

What are Isaac Newton’s Laws of Motion?

May 3, 2021 By Emma Vanstone Leave a Comment

Isaac Newton’s laws of motion explain the relationship between an object and the forces acting on it. The laws might seem very obvious today, but when Isaac Newton was alive, they were revolutionary and formed the basis of modern physics. Isaac Newton built on ideas from Galileo Galilei, Jean Richer and Rene Descartes. It is also said that Edmund Halley convinced Isaac Newton to write Principia .

Newton recorded his ideas about the laws of motion and gravity in a book called Principia .

A force is anything that can change the motion of an object. When you throw a ball, you exert a force on it in a specific direction which is the direction in which it moves. The harder you throw, the further the ball travels as a bigger force is acting on it.

What are Newton’s Laws of Motion?

What is newton’s first law.

An object at rest will remain at rest.

An object in motion will keep moving with the same speed and in the same direction unless another force acts on it.

Basically, that means a motionless object will stay motionless unless a force acts on it. Imagine a toy car on the floor; it will only move if someone pushes it.

If the forces acting on a body are balanced, it will move at a constant velocity.

Experiments to Demonstrate Newton’s First Law

A rocket mouse is a fantastic demonstration of Newton’s First Law . The cone on the milk bottle is at rest until the force of air being pushed out of the milk bottle ( when you squeeze it ) sends the cone flying into the air.

Newton’s First Law is sometimes referred to as the Law of Inertia . This means that if an object is moving in a straight line, it will continue moving in a straight line unless a force acts on it.

An excellent way to demonstrate this is with a simple inertia experiment .

If you pull the yellow card fast enough, the black column will fall to the side, and the lemon will fall in a straight line into the glass! The video below shows this in action.

What about friction?

We know that, generally, objects don’t continue moving forever because they are slowed down by friction. For example, a ball rolling on a carpet slows down much faster than a ball rolling on a smooth floor, as there is more friction between a ball on a rough surface than on a smooth surface. You can demonstrate this by making a friction ramp .

In space where there is no friction from air, objects keep moving for much longer.

Newton’s Second Law

Newton’s Second Law is all about the relationship between the force applied to a body and the change in its momentum or acceleration.

Force is equal to mass times acceleration

F – force applied ( N )

a – Acceleration (m/s 2 )

m – Mass ( kg )

What does that mean? Newton’s Second Law states that force is equal to mass times acceleration. A change in momentum is proportional to the change in the force applied.

Imagine kicking a light plastic football and a heavy football. Moving the heavier ball the same distance as the lighter ball takes a lot more force.

Newton’s Third Law

Every action has an equal and opposite reaction.

Newton’s Third Law states that for every action, there is always an equal and opposite reaction. When one body acts on another, it experiences an equal and opposite reaction from the other body.

If you were to push an object, the object pushes back against you, and if you stop pushing, the force back against you stops as well.

Imagine a rocket launching. The downward thrust created by the engine is the action, and the reaction is an opposite upward thrust forcing the rocket into the air.

A rocket will continue moving upwards as long as there is a resultant upwards force. If the upwards thrust force ceased, the resultant force would be downward.

Experiments to demonstrate all three of Newton’s Laws of Motion

A film canister rocket or mini bottle rocket is great for demonstrating all three of Newton’s Laws.

Newton’s First Law

The film canister remains motionless unless something is added to create a force ( usually an effervescent vitamin tablet and water ).

Acceleration is affected by the mass of an object. If you increase the mass of the film canister, you’ll find it moves more slowly and doesn’t fly as high.

The downward force on the film canister lid creates an opposite upwards force on the body of the canister, which flies up into the air.

More experiments to demonstrate forces

Think about some of the difficulties astronauts experience in space with this hands on activity about docking with the ISS .

Find out more about Isaac Newton , Galileo and other famous scientists.

Learn about gravity with straw rockets, magnets and water bottles in this selection of easy gravity experiments .

Finally, try one of these easy investigations for learning about forces and motion .

Last Updated on January 12, 2023 by Emma Vanstone

Safety Notice

Science Sparks ( Wild Sparks Enterprises Ltd ) are not liable for the actions of activity of any person who uses the information in this resource or in any of the suggested further resources. Science Sparks assume no liability with regard to injuries or damage to property that may occur as a result of using the information and carrying out the practical activities contained in this resource or in any of the suggested further resources.

These activities are designed to be carried out by children working with a parent, guardian or other appropriate adult. The adult involved is fully responsible for ensuring that the activities are carried out safely.

24 Elementary Force and Motion Experiments & Activities

Get teaching with these  force and motion  experiments, activities and videos to use in the elementary classroom. This collection of  force and motion activities and resources should help you cover the topics like  texture, gravity, incline and simple machines .

If you’re looking for helpful ideas and lesson plans – then this is the place to start!

Do you need a refresher as the teacher before planning your simple machines unit? This simple machines facts page is an excellent (and easy) way to jog your memory.

Force and Motion Experiments

Let’s plan some force and motion experiments for all elementary grades. Some of these can be adapted for different grade levels.

Set up ramps with different textures and send toy cars down. Use lots of questions to guide young students to extend their exploration.

Create catapults to explore how to make simple machines. With plastic utensils and marshmallows you’re set to build.

Take what you learned about building catapults in the above experiment to build a STEM engineering challenge. Students have to build a basketball hoop with classroom objects and recycled materials.

Skip the cars on an incline and go for liquids! Create a viscosity race with stuff from your fridge. Talk about how resistance to flowing is called viscosity and have fun.

Create a simple machines challenge . Students must create 3 ways to move a lion (or another small toy) using simple machines. Perfect to accompany the (affiliate) book How Do You Lift a Lion ?

Explore Newton’s first law together – the law of inertia – by seeing it in action. Create towers with note cards, string and a tower to feel the law as you take out each card separately, quickly or try to pull them all out at once!

Explore how to move the fulcrum on a lever to experiment how it impacts ease of use. All you need are some simple tools like rulers, a semi-heavy object and something to be the fulcrum.

A video explaining how a lever works is included.

Conduct trials with toy cars to see how you can make them go faster. Record the distance, time and speed with a free recording sheet.

Save a few water bottles and fill them with dry rice. Your students will love exploring friction in this floating rice experiment .

Aren’t those fun and clever force and motion experiments? Let’s move onto activities to help reinforce what you’ve taught.

Force and Motion Activities

After learning about how friction and force moves a roller coaster , set up your classroom to bring the concept to life.

Don’t be afraid to get messy! Combine art with science in this  force and motion marble painting activity .

Work on note taking. Use free simple machine notebooking pages and have students describe the lever, pulley, inclined plane, wedge, screw and wheel and axle. This would be a good resource for upper elementary.

Build a winch with paper towel tubes, spool and a straw. Students could make this recycled materials winch in pairs or small groups.

Attempt to lift heavier objects (by adding pennies to the object being lifted) feeling the change in force it takes to pull it up.

Make a foldable to summarize Sir Isaac Newton’s Laws of Motion . Write each law and illustrate on the flap.

Force and Motion Free Games Online

Experiment online (for kindergarten and first grade ) with this push and pull online activity. [no longer available]

Try this forces and movement interactive game for first and second grade . [no longer available]

Experiment with forces in action with this online activity for 10-11 year olds. [no longer available]

While it’s tricky to build flying contraptions in the classroom – use this how do things fly online simulator to design your own airplanes can make it happen – virtually.

Learn about drag, lift, thrust and weight in this interactive activity.

Your students will totally get into this online simple machines game . This game can be challenging – but your students will learn! Reading skills are needed.

Explore forces, loads, materials and shapes with this interactive  force and motion building big activity . This is neat for upper elementary students to see simulated (but interactive) examples of what they are learning about – with more options than you can explore in the classroom.

Force and Motion Videos for Elementary

Here is a list of more force and motion videos for 4th and 5th grade.

Ready for more force and motion activities for the classroom? Check out these 19 Fun Ideas & Resources for Force and Motion .

More Science

• 28 Awesome STEM Challenges for the Elementary Classroom
• Clouds Science for Kids: 23 Smart Ideas for the Classroom
• 21 Super Activities for Teaching Moon Phases
• Rocks for Kids – 15 Fun Activities and Ideas

Teach Junkie

Leslie {aka the original Teach Junkie} loves learning new things to make teaching easier and more effective. She enjoys featuring creative classroom fun when she's not designing teacher shirts, making kindergarten lesson plans or planning her family's next trip to Disney World.

Advertisement

How Newton's Laws of Motion Work

• Share Content on Facebook
• Share Content on LinkedIn
• Share Content on Flipboard
• Share Content on Reddit
• Share Content via Email

Next to E = mc ² , F = ma is the most famous equation in all of physics. Yet many people remain mystified by this fairly simple algebraic expression. It's actually a mathematical representation of Isaac Newton 's second law of motion, one of the great scientist's most important contributions. The "second" implies that other laws exist, and, luckily for students and trivia hounds everywhere, there are only two additional laws of motion. Here they are :

• Every object persists in its state of rest or uniform motion — in a straight line unless it is compelled to change that state by forces impressed on it.
• Force is equal to the change in momentum per change in time. For a constant mass , force equals mass times acceleration.
• For every action, there is an equal and opposite reaction.

These three laws form the foundation of what is known as classical mechanics , or the science concerned with the motion of bodies related to the forces acting on it. The bodies in motion could be large objects, such as orbiting moons or planets, or they could be ordinary objects on Earth's surface, such as moving vehicles or speeding bullets. Even bodies at rest are fair game.

Where classical mechanics begins to fall apart is when it tries to describe the motion of very small bodies, such as electrons. Physicists had to create a new paradigm, known as quantum mechanics , to describe the behavior of objects at the atomic and subatomic level.

But quantum mechanics is beyond the scope of this article. Our focus will be classical mechanics and Newton's three laws . We'll examine each in detail, both from a theoretical and a practical point of view. We'll also discuss the history of Newton's laws , because how he arrived at his conclusions is just as important as the conclusions themselves. The best place to start, of course, is at the beginning with Newton's first law.

Newton's First Law (Law of Inertia)

A brief history of newton's laws, newton's second law (law of motion), newton's third law (law of force pairs), applications and limitations of newton's laws.

Let's restate Newton's first law in everyday terms:

The "forever" part is difficult to swallow sometimes. But imagine that you have three ramps set up as shown below. Also imagine that the ramps are infinitely long and infinitely smooth. You let a marble roll down the first ramp, which is set at a slight incline. The marble speeds up on its way down the ramp.

Now, you give a gentle push to the marble going uphill on the second ramp. It slows down as it goes up. Finally, you push a marble on a ramp that represents the middle state between the first two — in other words, a ramp that is perfectly horizontal. In this case, the marble will neither slow down nor speed up. In fact, it should keep rolling. Forever.

Physicists use the term inertia to describe this tendency of an object to resist a change in its motion. The Latin root for inertia is the same root for "inert," which means lacking the ability to move. So, you can see how scientists came up with the word. What's more amazing is that they came up with the concept. Inertia isn't an immediately apparent physical property, such as length or volume. It is, however, related to an object's mass. To understand how, consider the sumo wrestler and the boy shown below.

Let's say the wrestler on the left has a mass of 136 kilograms, and the boy on the right has a mass of 30 kilograms (scientists measure mass in kilograms). Remember the object of sumo wrestling is to move your opponent from his position. Which person in our example would be easier to move? Common sense tells you that the boy would be easier to move, or less resistant to inertia.

You experience inertia in a moving car all the time. In fact, seat belts exist in cars specifically to counteract the effects of inertia. Imagine for a moment that a car at a test track is traveling at a speed of 55 mph (80 kph). Now imagine that a crash test dummy is inside that car, riding in the front seat. If the car slams into a wall, the dummy flies forward into the dashboard.

Why? Because, according to Newton's first law, an object in motion will remain in motion until an outside force acts on it. When the car hits the wall, the dummy keeps moving in a straight line and at a constant speed until the dashboard applies a force. Seatbelts hold dummies (and passengers) down, protecting them from their own inertia.

Interestingly, Newton wasn't the first scientist to come up with the law of inertia. That honor goes to Galileo and to René Descartes. In fact, the marble-and-ramp thought experiment described previously is credited to Galileo. Newton owed much to events and people who preceded him. Before we continue with his other two laws, let's review some of the important history that informed them.

The Greek philosopher Aristotle dominated scientific thinking for many years. His views on motion were widely accepted because they seemed to support what people observed in nature. For example, Aristotle thought that weight affected falling objects. A heavier object, he argued, would reach the ground faster than a lighter object dropped at the same time from the same height. He also rejected the notion of inertia, asserting instead that a force must be constantly applied to keep something moving. Both of these concepts were wrong, but it would take many years — and several daring thinkers — to overturn them.

The first big blow to Aristotle's ideas came in the 16th century when Nicolaus Copernicus published his sun-centered model of the universe. Aristotle theorized that the sun , the moon and the planets all revolved around Earth on a set of celestial spheres. Copernicus proposed that the planets of the solar system revolved around the sun, not Earth. Although not a topic of mechanics per se, the heliocentric cosmology described by Copernicus revealed the vulnerability of Aristotle's science.

Galileo Galilei was the next to challenge the Greek philosopher's ideas. Galileo conducted two now-classic experiments that set the tone and tenor for all scientific work that would follow. In the first experiment, he dropped a cannonball and a musket ball from the Leaning Tower of Pisa. Aristotelian theory predicted that the cannonball, much more massive, would fall faster and hit the ground first. But Galileo found that the two objects fell at the same rate and struck the ground roughly at the same time.

Some historians question whether Galileo ever carried out the Pisa experiment, but he followed it with a second phase of work that has been well-documented. These experiments involved bronze balls of various sizes rolling down an inclined wood plane. Galileo recorded how far a ball would roll in each one-second interval. He found that the size of the ball didn't matter — the rate of its descent along the ramp remained constant. From this, he concluded that freely falling objects experience uniform acceleration regardless of mass, as long as extraneous forces, such as air resistance and friction, can be minimized.

But it was René Descartes, the great French philosopher, who would add new depth and dimension to inertial motion. In his "Principles of Philosophy," Descartes proposed three laws of nature. The first law states that each thing, as far as is in its power, always remains in the same state; and that consequently, when it is once moved, it always continues to move. The second holds that all movement is, of itself, along straight lines. This is Newton's first law, clearly stated in a book published in 1644 — when Newton was still a newborn!

Clearly, Isaac Newton studied Descartes. He put that studying to good use as he single-handedly launched the modern era of scientific thinking. Newton's work in mathematics resulted in integral and differential calculus. His work in optics led to the first reflecting telescope. And yet his most famous contribution came in the form of three relatively simple laws that could be used, with great predictive power, to describe the motion of objects on Earth and in the heavens. The first of these laws came directly from Descartes, but the remaining two belong to Newton alone.

He described all three in "The Mathematical Principles of Natural Philosophy," or the Principia, which was published in 1687. Today, the Principia remains one of the most influential books in the history of human existence. Much of its importance lies within the elegantly simple second law, F = ma , which is the topic of the next section.

You may be surprised to learn that Newton wasn't the genius behind the law of inertia. But Newton himself wrote that he was able to see so far only because he stood on "the shoulders of Giants." And see far he did. Although the law of inertia identified forces as the actions required to stop or start motion, it didn't quantify those forces. Newton's second law supplied the missing link by relating force to acceleration. This is what it said:

Technically, Newton equated force to the differential change in momentum per unit time. Momentum is a characteristic of a moving body determined by the product of the body's mass and velocity. To determine the differential change in momentum per unit time, Newton developed a new type of math — differential calculus. His original equation looked something like this:

F = (m)(Δv/Δt)

where the delta symbols signify change. Because acceleration is defined as the instantaneous change in velocity in an instant of time (Δv/Δt), the equation is often rewritten as:

The F , the m and the a in Newton's formula are very important concepts in mechanics. The F is force , a push or pull exerted on an object. The m is mass , a measure of how much matter is in an object. And the a is acceleration, which describes how an object's velocity changes over time. Velocity , which is similar to speed, is the distance an object travels in a certain amount of time.

The equation form of Newton's second law allows us to specify a unit of measurement for force. Because the standard unit of mass is the kilogram (kg) and the standard unit of acceleration is meters per second squared (m/s 2 ), the unit for force must be a product of the two — (kg)(m/s 2 ). This is a little awkward, so scientists decided to use a Newton as the official unit of force. One Newton, or N, is equivalent to 1 kilogram-meter per second squared. There are 4.448 N in 1 pound.

So, what can you do with Newton's second law? As it turns out, F = ma lets you quantify motion of every variety. Let's say, for example, you want to calculate the acceleration of the dog sled shown at left.

Now let's say that the mass of the sled stays at 50 kilograms and that another dog is added to the team. If we assume the second dog pulls with equal force to the first (100 N), the total force would be 200 N and the acceleration would be 4 m/s 2 . However, doubling the mass to 100 kilograms would halve the acceleration to 2 m/s 2 .

Finally, let's imagine that a second dog team is attached to the sled so that it can pull in the opposite direction.

This is important because Newton's second law is concerned with net forces. We could rewrite the law to say: When a net force acts on an object, the object accelerates in the direction of the net force.

Now imagine that one of the dogs on the left breaks free and runs away. Suddenly, the force pulling to the right is larger than the force pulling to the left, so the sled accelerates to the right.

What's not so obvious in our examples is that the sled is also applying a force on the dogs. In other words, all forces act in pairs. This is Newton's third law — and the topic of the next section.

Newton's third law is probably the most familiar. Everyone knows that every action has an equal and opposite reaction, right? Unfortunately, this statement lacks some necessary detail. This is a better way to say it:

Many people have trouble visualizing this law because it's not as intuitive. In fact, the best way to discuss the law of force pairs is by presenting examples. Let's start by considering a swimmer facing the wall of a pool. If she places her feet on the wall and pushes hard, what happens? She shoots backward, away from the wall.

Clearly, the swimmer is applying a force to the wall, but her motion indicates that a force is being applied to her, too. This force comes from the wall, and it's equal in magnitude and opposite in direction.

Next, think about a book lying on a table. What forces are acting on it? One big force is Earth's gravity. In fact, the book's weight is a measurement of Earth's gravitational attraction. So, if we say the book weighs 10 N, what we're really saying is that Earth is applying a force of 10 N on the book. The force is directed straight down, toward the center of the planet. Despite this force, the book remains motionless, which can only mean one thing: There must be another force, equal to 10 N, pushing upward. That equal and opposite force is coming from the table.

If you're catching on to Newton's third law, you should have noticed another force pair described in the paragraph above. Earth is applying a force on the book, so the book must be applying a force on Earth. Is that possible? Yes, it is, but the book is so small that it cannot appreciably accelerate something as large as a planet.

You see something similar, although on a much smaller scale, when a baseball bat strikes a ball. There's no doubt the bat applies a force to the ball: It accelerates rapidly after being struck. But the ball must also be applying a force to the bat. The mass of the ball, however, is small compared to the mass of the bat, which includes the batter attached to the end of it. Still, if you've ever seen a wooden baseball bat break into pieces as it strikes a ball, then you've seen firsthand evidence of the ball's force.

These examples don't show a practical application of Newton's third law. Is there a way to put force pairs to good use? Jet propulsion is one application. Used by animals such as squid and octopuses , as well as by certain airplanes and rockets, jet propulsion involves forcing a substance through an opening at high speed. In squid and octopuses, the substance is seawater, which is sucked in through the mantle and ejected through a siphon. Because the animal exerts a force on the water jet, the water jet exerts a force on the animal, causing it to move. A similar principle is at work in turbine-equipped jet planes and rockets in space.

Speaking of outer space, Newton's other laws apply there, too. By using his laws to analyze the motion of planets in space, Newton was able to come up with a universal law of gravitation.

By themselves, the three laws of motion are a crowning achievement, but Newton didn't stop there. He took those ideas and applied them to a problem that had stumped scientists for years: the motion of planets. Copernicus placed the sun at the center of a family of orbiting planets and moons, while the German astronomer Johannes Kepler proved that the shape of planetary orbits was elliptical, not circular. But no one had been able to explain the mechanics behind this motion. Then, as the story goes, Newton saw an apple fall to the ground and was seized by inspiration. Could a falling apple be related to a revolving planet or moon? Newton believed so. This was his thought process to prove it:

• An apple falling to the ground must be under the influence of a force, according to his second law. That force is gravity, which causes the apple to accelerate toward Earth's center.
• Newton reasoned that the moon might be under the influence of Earth's gravity, as well, but he had to explain why the moon didn't fall into Earth. Unlike the falling apple, it moved parallel to Earth's surface.
• What if, he wondered, the moon moved about Earth in the same way as a stone whirled around at the end of a string? If the holder of the string let go — and therefore stopped applying a force — the stone would obey the law of inertia and continue traveling in a straight line, like a tangent extending from the circumference of the circle.
• But if the holder of the string didn't let go, the stone would travel in a circular path, like the face of a clock. In one instant, the stone would be at 12 o'clock. In the next, it would be at 3 o'clock. A force is required to pull the stone inward so it continues its circular path or orbit. The force comes from the holder of the string.
• Next, Newton reasoned that the moon orbiting Earth was the same as the stone whirling around on its string. Earth behaved as the holder of the string, exerting an inward-directed force on the moon. This force was balanced by the moon's inertia, which tried to keep the moon moving in a straight-line tangent to the circular path.
• Finally, Newton extended this line of reasoning to any of the planets revolving around the sun. Each planet has inertial motion balanced by a gravitational attraction coming from the center of the sun.

It was a stunning insight — one that eventually led to the universal law of gravitation. According to this law, any two objects in the universe attract each other with a force that depends on two things: the masses of the interacting objects and the distance between them. More massive objects have bigger gravitational attractions. Distance diminishes this attraction. Newton expressed this mathematically in this equation:

F = G(m1m2/r 2 )

where F is the force of gravity between masses m1 and m2 , G is a universal constant and r is the distance between the centers of both masses.

Over the years, scientists in just about every discipline have tested Newton's laws of motion and found them to be amazingly predictive and reliable. But there are two instances where Newtonian physics break down. The first involves objects traveling at or near the speed of light. The second problem comes when Newton's laws are applied to very small objects, such as atoms or subatomic particles that fall in the realm of quantum mechanics.

Lots More Information

Related articles.

• How Isaac Newton Worked
• How Time Works
• 10 Isaac Newton Inventions
• How Special Relativity Works
• How Warp Speed Works

More Great Links

• Newton's Laws of Motion on NASA
• Newton's Laws of Motion: In Our Time, BBC Radio
• Barnes-Svarney, Patricia, Ed. "The New York Public Library Science Desk Reference." Macmillan. 1995.
• Crowther, J.G. "Six Great Scientists." Barnes & Noble Books. 1995.
• Dennis, Johnnie T. "The Complete Idiot's Guide to Physics." Alpha Books. 2003.
• Encyclopædia Britannica 2005, s.v. "Mechanics." CD-ROM, 2005.
• Encyclopædia Britannica 2005, s.v. "Newton's laws of motion." CD-ROM, 2005.
• Encyclopædia Britannica 2005, s.v. "Newton, Sir Isaac." CD-ROM, 2005.
• Gundersen, P. Erik. "The Handy Physics Answer Book." Visible Ink Press. 2003.
• Hobson, Art. "Physics: Concepts & Connections, Fourth Edition." Pearson Prentice Hall. 2007.
• Johnson, George. "The Ten Most Beautiful Experiments." Alfred A. Knopf. 2008.
• NASA. "Newton's Laws of Motion." Glenn Research Center. July 11, 2008. (July 21, 2008) http://www.grc.nasa.gov/WWW/K-12/airplane/newton.html
• NOVA. "Newton's Dark Secrets on NOVA" (July 21, 2008) http://www.pbs.org/wgbh/nova/newton/
• Scien­ce Channel. "Isaac Newton's Laws of Motion: Science Channel." (July 21, 2008) http://science.discovery.com/interactives/literacy/newton/newton.html

Please copy/paste the following text to properly cite this HowStuffWorks.com article:

Sciencing_Icons_Science SCIENCE

Sciencing_icons_biology biology, sciencing_icons_cells cells, sciencing_icons_molecular molecular, sciencing_icons_microorganisms microorganisms, sciencing_icons_genetics genetics, sciencing_icons_human body human body, sciencing_icons_ecology ecology, sciencing_icons_chemistry chemistry, sciencing_icons_atomic & molecular structure atomic & molecular structure, sciencing_icons_bonds bonds, sciencing_icons_reactions reactions, sciencing_icons_stoichiometry stoichiometry, sciencing_icons_solutions solutions, sciencing_icons_acids & bases acids & bases, sciencing_icons_thermodynamics thermodynamics, sciencing_icons_organic chemistry organic chemistry, sciencing_icons_physics physics, sciencing_icons_fundamentals-physics fundamentals, sciencing_icons_electronics electronics, sciencing_icons_waves waves, sciencing_icons_energy energy, sciencing_icons_fluid fluid, sciencing_icons_astronomy astronomy, sciencing_icons_geology geology, sciencing_icons_fundamentals-geology fundamentals, sciencing_icons_minerals & rocks minerals & rocks, sciencing_icons_earth scructure earth structure, sciencing_icons_fossils fossils, sciencing_icons_natural disasters natural disasters, sciencing_icons_nature nature, sciencing_icons_ecosystems ecosystems, sciencing_icons_environment environment, sciencing_icons_insects insects, sciencing_icons_plants & mushrooms plants & mushrooms, sciencing_icons_animals animals, sciencing_icons_math math, sciencing_icons_arithmetic arithmetic, sciencing_icons_addition & subtraction addition & subtraction, sciencing_icons_multiplication & division multiplication & division, sciencing_icons_decimals decimals, sciencing_icons_fractions fractions, sciencing_icons_conversions conversions, sciencing_icons_algebra algebra, sciencing_icons_working with units working with units, sciencing_icons_equations & expressions equations & expressions, sciencing_icons_ratios & proportions ratios & proportions, sciencing_icons_inequalities inequalities, sciencing_icons_exponents & logarithms exponents & logarithms, sciencing_icons_factorization factorization, sciencing_icons_functions functions, sciencing_icons_linear equations linear equations, sciencing_icons_graphs graphs, sciencing_icons_quadratics quadratics, sciencing_icons_polynomials polynomials, sciencing_icons_geometry geometry, sciencing_icons_fundamentals-geometry fundamentals, sciencing_icons_cartesian cartesian, sciencing_icons_circles circles, sciencing_icons_solids solids, sciencing_icons_trigonometry trigonometry, sciencing_icons_probability-statistics probability & statistics, sciencing_icons_mean-median-mode mean/median/mode, sciencing_icons_independent-dependent variables independent/dependent variables, sciencing_icons_deviation deviation, sciencing_icons_correlation correlation, sciencing_icons_sampling sampling, sciencing_icons_distributions distributions, sciencing_icons_probability probability, sciencing_icons_calculus calculus, sciencing_icons_differentiation-integration differentiation/integration, sciencing_icons_application application, sciencing_icons_projects projects, sciencing_icons_news news.

• Share Tweet Email Print
• Home ⋅
• Science ⋅
• Physics ⋅
• Mechanics (Physics): The Study of Motion.

How To Demonstrate Newton's Laws of Motion

Kinetic Energy Experiments for Kids

Sir Isaac Newton developed three laws of motion. The first law of inertia says that an object’s speed will not change unless something makes it change. The second law: the strength of the force equals the mass of the object times the resulting acceleration. Finally, the third law says that for every action there is a reaction. In some classes, these laws are taught by having the students memorize the words, instead of lecturing students or children about these somewhat complex laws. Here are a few ways to demonstrate the laws and gain a better understanding.

Newton's First Law of Motion

Place the hard boiled egg on its side and spin it. Put your finger on it gently while it is still spinning in order to stop it. Remove your finger when it stops.

Place the raw egg on its side and spin it. Place your finger gently on the egg until it stops. Once you remove your finger, the egg should start to spin again. The liquid inside the egg has not stopped so it will continue to spin until enough force is applied.

Push an empty shopping cart and stop it. Then push a loaded shopping cart and stop it. It takes more effort to push the loaded cart than an empty one.

Newton's Second Law of Motion

Drop a rock or marble and a wadded-up piece of paper at the same time. They fall at the same rate of speed, but the rock's mass is greater so it hits with greater force.

Push the roller skates or toy cars at the same time.

Push one harder than the other. One had greater force applied to it so it moves faster.

Newton's Third Law of Motion

Pull one ball or swing back and let it go.

It will swing into the other balls making the ball at the other end swing.

Explain how this represents an equal and opposite reaction.

Things You'll Need

Related articles, newton's laws of motion for kids, how to float an egg in water, how to build a successful egg drop container for physics, how to drop an egg without breaking it by using straws..., newton's laws of motion made easy, science project on gravity and motion for third graders, background information on egg drop experiments, science experiments on bouncing & rolling, how does salt water make an egg float, science project egg experiments, easy one day middle school science fair projects, how does newton's laws of motion interact with tennis, what are some examples of the laws of motion, types of newton scooters, how to make egg launchers, how to make a simple machine project for school, how to mix vinegar & baking soda in a bottle rocket, the science behind the egg drop experiment.

• Home Science Tools: Laws of Motion

About the Author

Rob Hildegard has more than 25 years of ghostwriting experience. His credits include hard backed books and numerous academic articles. Hildegard's writing preferences and specialties include health issues as they relate to men, legal issues and sports. His work has appeared on eZines and eHow.

Find Your Next Great Science Fair Project! GO

What Are Newton's Laws of Motion?

Newton's First, Second and Third Laws of Motion

Getty Images / Dmitrii Guzhanin 

• Chemical Laws
• Periodic Table
• Projects & Experiments
• Scientific Method
• Biochemistry
• Physical Chemistry
• Medical Chemistry
• Chemistry In Everyday Life
• Famous Chemists
• Activities for Kids
• Abbreviations & Acronyms
• Weather & Climate
• Ph.D., Biomedical Sciences, University of Tennessee at Knoxville
• B.A., Physics and Mathematics, Hastings College

Newton's Laws of Motion help us understand how objects behave when standing still; when moving, and when forces act upon them. There are three laws of motion. Here is a description of Sir Isaac Newton's Laws of Motion and a summary of what they mean.

Newton's First Law of Motion

Newton's First Law of Motion states that an object in motion tends to stay in motion unless an external force acts upon it. Similarly, if the object is at rest, it will remain unless an unbalanced force acts upon it. Newton's First Law of Motion is also known as the Law of Inertia .

What Newton's First Law is saying is that objects behave predictably. If a ball is sitting on your table, it isn't going to start rolling or fall off the table unless a force acts upon it to cause it to do so. Moving objects don't change their direction unless a force causes them to move from their path.

As you know, if you slide a block across a table, it eventually stops rather than continuing forever. This is because the frictional force opposes the continued movement. If you throw a ball out in space, there is much less resistance. The ball will continue onward for a much greater distance.

Newton's Second Law of Motion

Newton's Second Law of Motion states that when a force acts on an object, it will cause the object to accelerate. The larger the object's mass, the greater the force will need to be to cause it to accelerate. This Law may be written as force = mass x acceleration or:

F = m * a

Another way to state the Second Law is to say it takes more force to move a heavy object than it does to move a light object. Simple, right? The law also explains deceleration or slowing down. You can think of deceleration as acceleration with a negative sign on it. For example, a ball rolling down a hill moves faster or accelerates as gravity acts on it in the same direction as the motion (acceleration is positive). If a ball is rolled up a hill, the force of gravity acts on it in the opposite direction of the motion (acceleration is negative or the ball decelerates).

Newton's Third Law of Motion

Newton's Third Law of Motion states that for every action, there is an equal and opposite reaction.

This means that pushing on an object causes that object to push back against you, the same amount but in the opposite direction. For example, when you are standing on the ground, you are pushing down on the Earth with the same magnitude of force it is pushing back up at you.

History of Newton's Laws of Motion

Sir Isaac Newton introduced the three Newton's laws of motion in 1687 in his book entitled "Philosophiae Naturalis Principia Mathematica" (or simply "The Principia"). The same book also discussed the theory of gravity . This one volume described the main rules still used in classical mechanics today.

• The Combined Gas Law in Chemistry
• Entropy Definition in Science
• Newton Definition
• Oxidation Definition and Example in Chemistry
• What Is the Density of Air at STP?
• Periodic Table Definition in Chemistry
• Stoichiometry Definition in Chemistry
• What Is an Element in Chemistry? Definition and Examples
• Chemical Property Definition and Examples
• Molar Ratio: Definition and Examples
• Element Symbol Definition in Chemistry
• Solution Definition in Chemistry
• Joule Definition (Unit in Science)
• Percent Yield Definition and Formula
• Double Replacement Reaction Definition

• History & Society
• Science & Tech
• Biographies
• Animals & Nature
• Geography & Travel
• Arts & Culture
• Games & Quizzes
• On This Day
• One Good Fact
• New Articles
• Lifestyles & Social Issues
• Philosophy & Religion
• Politics, Law & Government
• World History
• Health & Medicine
• Browse Biographies
• Birds, Reptiles & Other Vertebrates
• Bugs, Mollusks & Other Invertebrates
• Environment
• Fossils & Geologic Time
• Entertainment & Pop Culture
• Sports & Recreation
• Visual Arts
• Demystified
• Image Galleries
• Infographics
• Top Questions
• Britannica Kids
• Saving Earth
• Space Next 50
• Student Center
• Introduction & Top Questions

Newton’s first law: the law of inertia

• Newton’s second law: F = ma
• Newton’s third law: the law of action and reaction
• Influence of Newton’s laws

What are Newton’s laws of motion?

• What is Isaac Newton most famous for?
• How was Isaac Newton educated?
• What was Isaac Newton’s childhood like?

Newton’s laws of motion

Our editors will review what you’ve submitted and determine whether to revise the article.

• Energy Wave Theory - Laws of Motion
• Khan Academy - Newton's laws of motion
• Physics LibreTexts - Newton's Laws of Motion
• Gresham College - Newton's Laws
• The Physics Classroom - Newton's Laws
• Frontiers - Complexity and Newton's Laws
• Space.com - What are Newton's laws of motion?
• NASA - Glenn Research Center - Newton’s Laws of Motion
• Lehman College - Newton’s Laws of Motion
• LiveScience - Newton’s Laws of Motion
• NeoK12 - Educational Videos and Games for School Kids - Laws of Motion
• Table Of Contents

Newton’s laws of motion relate an object’s motion to the forces acting on it. In the first law, an object will not change its motion unless a force acts on it. In the second law, the force on an object is equal to its mass times its acceleration. In the third law, when two objects interact, they apply forces to each other of equal magnitude and opposite direction.

Why are Newton’s laws of motion important?

Newton’s laws of motion are important because they are the foundation of classical mechanics, one of the main branches of physics . Mechanics is the study of how objects move or do not move when forces act upon them.

Newton’s laws of motion , three statements describing the relations between the forces acting on a body and the motion of the body, first formulated by English physicist and mathematician Isaac Newton , which are the foundation of classical mechanics .

Newton’s first law states that if a body is at rest or moving at a constant speed in a straight line, it will remain at rest or keep moving in a straight line at constant speed unless it is acted upon by a force . In fact, in classical Newtonian mechanics, there is no important distinction between rest and uniform motion in a straight line; they may be regarded as the same state of motion seen by different observers, one moving at the same velocity as the particle and the other moving at constant velocity with respect to the particle. This postulate is known as the law of inertia .

The law of inertia was first formulated by Galileo Galilei for horizontal motion on Earth and was later generalized by René Descartes . Although the principle of inertia is the starting point and the fundamental assumption of classical mechanics, it is less than intuitively obvious to the untrained eye. In Aristotelian mechanics and in ordinary experience, objects that are not being pushed tend to come to rest. The law of inertia was deduced by Galileo from his experiments with balls rolling down inclined planes.

For Galileo, the principle of inertia was fundamental to his central scientific task: he had to explain how is it possible that if Earth is really spinning on its axis and orbiting the Sun, we do not sense that motion. The principle of inertia helps to provide the answer: since we are in motion together with Earth and our natural tendency is to retain that motion, Earth appears to us to be at rest. Thus, the principle of inertia, far from being a statement of the obvious, was once a central issue of scientific contention . By the time Newton had sorted out all the details, it was possible to accurately account for the small deviations from this picture caused by the fact that the motion of Earth’s surface is not uniform motion in a straight line (the effects of rotational motion are discussed below). In the Newtonian formulation, the common observation that bodies that are not pushed tend to come to rest is attributed to the fact that they have unbalanced forces acting on them, such as friction and air resistance.

Summer holiday science: turn your home into a lab with these three easy experiments

Associate Professor in Biology, University of Limerick

Disclosure statement

Audrey O'Grady receives funding from Science Foundation Ireland. She is affiliated with Department of Biological Sciences, University of Limerick.

University of Limerick provides funding as a member of The Conversation UK.

View all partners

Many people think science is difficult and needs special equipment, but that’s not true.

Science can be explored at home using everyday materials. Everyone, especially children, naturally ask questions about the world around them, and science offers a structured way to find answers.

Misconceptions about the difficulty of science often stem from a lack of exposure to its fun and engaging side. Science can be as simple as observing nature, mixing ingredients or exploring the properties of objects. It’s not just for experts in white coats, but for everyone.

Don’t take my word for it. Below are three experiments that can be done at home with children who are primary school age and older.

Extract DNA from bananas

DNA is all the genetic information inside cells. Every living thing has DNA, including bananas.

Did you know you can extract DNA from banana cells?

What you need: ¼ ripe banana, Ziploc bag, salt, water, washing-up liquid, rubbing alcohol (from a pharmacy), coffee filter paper, stirrer.

What you do:

Place a pinch of salt into about 20ml of water in a cup.

Add the salty water to the Ziploc bag with a quarter of a banana and mash the banana up with the salty water inside the bag, using your hands. Mashing the banana separates out the banana cells. The salty water helps clump the DNA together.

Once the banana is mashed up well, pour the banana and salty water into a coffee filter (you can lay the filter in the cup you used to make the salty water). Filtering removes the big clumps of banana cells.

Once a few ml have filtered out, add a drop of washing-up liquid and swirl gently. Washing-up liquid breaks down the fats in the cell membranes which makes the DNA separate from the other parts of the cell.

Slowly add some rubbing alcohol (about 10ml) to the filtered solution. DNA is insoluble in alcohol, therefore the DNA will clump together away from the alcohol and float, making it easy to see.

DNA will start to precipitate out looking slightly cloudy and stringy. What you’re seeing is thousands of DNA strands – the strands are too small to be seen even with a normal microscope. Scientists use powerful equipment to see individual strands.

Learn how plants ‘drink’ water

What you need: celery stalks (with their leaves), glass or clear cup, water, food dye, camera.

• Fill the glass ¾ full with water and add 10 drops of food dye.
• Place a celery stalk into the glass of coloured water. Take a photograph of the celery.
• For two to three days, photograph the celery at the same time every day. Make sure you take a photograph at the very start of the experiment.

What happens and why?

All plants, such as celery, have vertical tubes that act like a transport system. These narrow tubes draw up water using a phenomenon known as capillarity.

Imagine you have a thin straw and you dip it into a glass of water. Have you ever noticed how the water climbs up the straw a little bit, even though you didn’t suck on it? This is because of capillarity.

In plants, capillarity helps move water from the roots to the leaves. Plants have tiny tubes inside them, like thin straws, called capillaries. The water sticks to the sides of these tubes and climbs up. In your experiment, you will see the food dye in the water make its way to the leaves.

Build a balloon-powered racecar

What you need: tape, scissors, two skewers, cardboard, four bottle caps, one straw, one balloon.

• Cut the cardboard to about 10cm long and 5cm wide. This will form the base of your car.
• Make holes in the centre of four bottle caps. These are your wheels.
• To make the axles insert the wooden skewers through the holes in the cap. You will need to cut the skewers to fit the width of the cardboard base, but leave room for the wheels.
• Secure the wheels to the skewers with tape.
• Attach the axles to the underside of the car base with tape, ensuring the wheels can spin freely.
• Insert a straw into the opening of a balloon and secure it with tape, ensuring there are no air leaks.
• Attach the other end of the straw to the top of the car base, positioning it so the balloon can inflate and deflate towards the back of the car. Secure the straw with tape.
• Inflate the balloon through the straw, pinch the straw to hold the air, place the car on a flat surface, then release the straw.

The inflated balloon stores potential energy when blown up. When the air is released, Newton’s third law of motion kicks into gear: for every action, there is an equal and opposite reaction.

As the air rushes out of the balloon (action), it pushes the car in the opposite direction (reaction). The escaping air propels the car forward, making it move across the surface.

• Science experiments

Microsoft and Citrix Technical Consultant

Casual Facilitator: GERRIC Student Programs - Arts, Design and Architecture

Senior Lecturer, Digital Advertising

Manager, Centre Policy and Translation

Newsletter and Deputy Social Media Producer

You are using an outdated browser. Please upgrade your browser to improve your experience.

OR, Choose a Category

Newton’s First Law of Motion

Physicists study matter – all of the “stuff” in the universe and how that “stuff” moves. One of the most famous physicists of all time was  Sir Isaac Newton . Sir Isaac is most famous for explaining  gravity , a concept we are so familiar with now it seems obvious to us. He is also famous for explaining how stuff moves in his  Three Laws of Motion . Today we are going to look at  Newton’s First Law of Motion  called  Inertia . This law states that a still object will stay still unless a force pushes or pulls it. A moving object will stay moving unless a force pushes or pulls it.

Gravity and friction are forces that constantly push and pull the “stuff” on earth. So, when we roll a ball, it slowly comes to a stop. On the moon, where there is less gravity and friction, “stuff” floats, and keeps floating. Try one of the experiments below to see Newton’s first law of motion in action.

Experiments:

• Steve Spangler: Egg Drop
• Steve Spangler: Tablecloth Trick
• Steve Spangler: The Coin Drop
• Bill Nye Pages of Inertia
• Hunkin’s Experiments: Inertia Cartoon

Websites, Activites & Printables:

• NASA: Newton’s First Law of Motion
• Why Don’t I Fall Out When a Roller Coaster Goes Upside Down?
• Khan Academy Video: Newton’s First Law of Motion
• IndyPL Blog: Newton’s Second Law of Motion
• IndyPL Blog: Newton’s Third Law of Motion

You can ask a math and science expert for homework help by calling the  Ask Rose Homework Hotline . They provide FREE math and science homework help to Indiana students in grades 6-12.

e-Books and Audiobooks

Use your indyPL Library Card to check out books about Sir Isaac Newton at any of our  locations , or  check out Sir Isaac Newton e-books and audiobooks from OverDrive Kids  right to your device! If you have never used OverDrive before, you can learn how to use e-books  and  learn how to use audiobooks .

Need more help?  Ask a Library staff member at any of our locations  or  call, text or email Ask-a-Librarian . Additionally, the Tinker Station helpline at (317) 275-4500 is also available. It is staffed by device experts who can answer questions about how to read, watch and listen on a PC, tablet or phone.

Newton’s Laws of Motion: The Science Behind How Things Move

Newton’s Laws of Motion explain force and motion, or why things move the way they do. They are great concepts to explore by doing a science experiment. These are especially good science project ideas for kids who like to move! The concepts can often be explained using sports equipment or by understanding how amusement park rides work. These books offer ideas for physics experiments that demonstrate force and motion and the laws that govern them. Some of them provide the background information needed for the report that is often required to go with projects for the science fair.

View more…

• Tags Homework Help , Science Experiments

The heiress at Harvard who helped revolutionize murder investigations — and the case she couldn’t forget

Frances glessner lee didn’t want to be known as a “rich woman who didn’t have enough to do.” in her 60s, she became a pioneer of forensic science..

O n an afternoon in July 1940, several day laborers were walking through the woods in Dartmouth, Massachusetts, searching for blueberries on their lunch break. About 12 feet off the trail, under the branches of a pine, one of them stumbled across what looked like a brown burlap sack. As he edged closer, he realized with horror it wasn’t a sack at all. It was a dead body.

Police officers arrived at the grim scene. The victim appeared to be a young woman, but her corpse was significantly decomposed. Not far away was a secluded dirt road known as a Lovers’ Lane for parking couples wanting privacy. A rifle shooting range was also nearby — a half-dozen .22-caliber cartridges were found near the woman’s body. A heavy rope encircled her neck and was tied to her wrists. She wore a brown plaid dress and one of her silk stockings bound her ankles.

It was the most brutal murder the local police had seen in years. Detectives of the era received little training in crime scene investigation, and they were in over their heads. It was time to call in, perhaps begrudgingly, the forensic scientists from Harvard Medical School — the “college boys,” as the officers sometimes put it.

The teletype message arrived at 2:30 that same afternoon, July 31, summoning staff from Harvard’s new department of legal medicine. Dr. Alan Moritz and his colleagues drove from Boston to Dartmouth right away, and were relieved to find police hadn’t disturbed the body. A Harvard pathologist had once arrived at a home to find officers scrubbing blood evidence from the wall — they didn’t want to bump against it and stain their uniforms.

Examining the scene closely, Moritz knew there was much to do, including a careful autopsy, leaf and insect analysis, and experiments with the rope. But he could already conclude this much, judging by the broken stems of nearby underbrush — she’d likely been murdered elsewhere, and dragged by the feet to this spot.

Although it would eventually become clear that life hadn’t been kind to this young woman, she would receive one of the most advanced death investigations of the time. And it would be largely thanks to the most unlikely of figures: a strong-willed, unconventional heiress in her 60s named Frances Glessner Lee, who was on a mission to revolutionize murder investigations. In the years to come, Lee’s life, and the woman’s death, would connect the two in unexpected ways.

Advertisement

Lee stepped into the male-dominated world of detective work later in life, like a real-world Miss Marple from Agatha Christie’s novels. Lee, who favored brimless hats and dark dresses, was described in 1949 by a reporter as “motherly looking” and “amply girthed.” But a police detective she trained offered a more telling description. She was “unquestionably,” he said, “one of the world’s most astute criminologists.”

Lee was the driving force behind Harvard’s new department of legal medicine, the first program of its kind in the United States. She’d pursue her mission of professionalizing murder investigations with single-minded focus, despite significant odds stacked against her at Harvard and in local police departments across the country. She contributed much of her personal fortune, political acumen, and even her artistic talents to making sure all victims — man or woman, rich or poor — got investigations that were full and fair.

With resolve as deep as her pockets, she’d will the department into existence, be appointed an official consultant, and be named a founder of crime scene investigation. And among her many other accomplishments, it would turn out, was engineering a way to make sure the woman in the woods­ would not be forgotten.

FRANCES GLESSNER LEE’S quest to reform homicide investigations started at a low moment in her life. A divorced mother of three adult children, she had grown weary of her image as a rich woman with too much time on her hands.

Born in 1878, Lee grew up on one of the most affluent streets in Chicago, in a 17,000-square-foot mansion that is now a museum . Her father’s fortune came from building International Harvester, the maker of agricultural and construction machinery. She and her older brother were both bright and received a rigorous education at home by tutors, including learning multiple languages. He went off to Harvard, but she wouldn’t go to college. Her parents believed “a lady didn’t go to school,” she once told a reporter years later.

Lee was also taught how to run a household, be a generous hostess, and pursue crafts such as needlework. She showed an aptitude for noticing the smallest details and significant artistic talent, according to 18 Tiny Deaths , a biography of her by Bruce Goldfarb. For her mother’s birthday, she once made a scale-model of the 90-member Chicago Symphony Orchestra, where each musician was recognizable and had a miniature instrument and tiny musical score.

In her late teens, Lee was sent on a 14-month grand tour of Europe, then introduced to Chicago high society as a debutante in November 1897. Just shy of her 20th birthday, she married a Southern lawyer named Blewett Harrison Lee, a distant relative of Robert E. Lee. They had three children, but Lee felt chronically unhappy and hemmed in by the marriage. In her mid-30s, she took the then-unusual step of obtaining a divorce. She’d never marry again.

Over the years, Lee adopted New England as her home, dividing her time between her family’s 1,400-acre summer estate, The Rocks, in Bethlehem, New Hampshire, and the Ritz-Carlton hotel in Boston. In this city in the early 1930s, a series of conversations with Dr. George Magrath, a close Harvard classmate of her brother’s, inspired a new intellectual passion — the investigation of murder.

Magrath was a longtime Suffolk County medical examiner who, over his career, testified in some 2,000 court cases and investigated 21,000 deaths. A dapper dresser, he cut an unusual figure in town. He wore pince-nez for glasses, smoked a pipe, and lived for years at Boston’s private St. Botolph Club, then on Newbury Street. He ate only one meal a day — at midnight.

Lee liked him immediately.

She listened, enthralled, as Magrath shared stories of complex autopsies, many of which revealed surprising causes of death missed by bumbling police. In some cases, murders were masked as suicides; at other times, police mistook suicides for murders. His passion for the inner workings of the human body — and what clues they reveal about death and a person’s place in society — mesmerized Lee.

She began to join Magrath at autopsies and crime scenes, poring through murder case files and tracking state-by-stage legislation related to death investigations. She and Magrath shared a vision of the system of trained medical examiners — which had existed in Suffolk County in Massachusetts since 1877 — going nationwide.

Lee wanted it to replace the patchwork system of coroners, typically funeral directors, political appointees, or elected officials with no medical training making critical decisions about causes of death. That system dominated the country in the 1940s. Today, more than half of Americans live in areas governed by coroners.

In 1931, at the age of 53, Lee gave $4,500 a year (about $90,000 in today’s dollars) to fund a Harvard Medical School professorship for Magrath, the first such forensic science position in the country. She’d soon donate a library in Magrath’s honor with 1,000 volumes she’d collected, including the memoirs President Garfield’s assassin penned while he awaited the gallows.

But her role went deeper than money. With her own desk at Harvard, she worked as Magrath’s teaching assistant, and later was named a consultant. To Lee it felt like finally, in middle age, she was contributing something important — that she had a mission. “For many years I have hoped that I might do something in my lifetime that should be of significant value to the community,” she once told a reporter. She “was sincerely glad to find that my opportunity to serve lay here at Harvard Medical School.”

The intense ties between Magrath, the lifelong bachelor, and Lee, the long-divorced heiress, sometimes raised eyebrows. “At times Lee bordered on the coquettish, referring to herself in unpublished writing for Magrath as ‘Ye Saucy Scrybe,’” Goldfarb writes in Lee’s biography, “and yet in correspondence between the two, they never used terms of endearment. Lee always called him Dr. Magrath, and to him, she was Mrs. Frances G. Lee.”

As Magrath’s health began failing — he died in 1938 at 68 — Lee’s obsession with forensic science did not diminish. She donated the equivalent of about $5 million to start the department of legal medicine , a place to teach cutting-edge methods in blood spatter analysis, gunpowder chemistry, and more. She suggested to Harvard she might be willing to write an even larger gift into her will, perhaps as much as $22 million in today’s dollars.

Lee’s new department, she vowed, was not to be corrupted by politics or other outside influences. “We testify for no party,” its official credo read, “neither for the prosecution nor for the defense but for the Truth alone.”

WHEN LEE STAYED at the Ritz, she’d eat meals at her usual table overlooking the Public Garden. On August 1, 1940, if she’d been reading The Boston Daily Globe, she’d have found it weighty with portents of looming war. Lowering the draft age was in discussion, and the US House had just passed the biggest appropriations bill in history, $5 billion to build warships and warplanes. The 23-year-old son of the ambassador to Great Britain had just published his Harvard senior thesis, “Why England Slept.” His name was John F. Kennedy.

But above all the stories, above everything on the front page of that evening’s edition, stretched a headline in bold capital letters: “GIRL, 22, TRUSSED AND SLAIN.”

The victim discovered in the Dartmouth woods two days earlier had been tentatively identified as Irene Perry, a 22-year-old single mother who couldn’t have come from a background more different than Lee’s. If not for the shocking brutality of Perry’s murder — and the provocative circumstances around what the press nationwide immediately dubbed the “Lover’s Lane Slaying” — it’s doubtful her death, like her life, would have risen to the notice of the newspapers at all.

Perry was 15 years old when her mother died, and dropped out of school to care for her father, four brothers, and eight sisters, news reports said. When she was around 20, she had a baby on her own. The Catholic immigrant family — “Perry” was an Anglicized version of their Portuguese name — lived in a modest home in New Bedford, where Perry’s father worked at the country club as a greenskeeper. Hers was a hard life. Later, some said she dreamed of disappearing to Europe where she could start anew.

She’d last been seen on the evening of June 29, when she left her 2-year-old son, Donald, at home and headed to a store about a half-mile away to run an errand, with a dollar from her father in hand. A slim woman with dark hair and large, deep-set eyes, she wore a brown plaid jacket and dress and a blouse with puffed sleeves. It was the last time her family saw her alive.

Perry’s father didn’t report her missing until the next day. She’d had boyfriends, and apparently this wasn’t the first time she hadn’t returned home at night. A month later, he got a heart-stopping call: Police asked him to come to a funeral parlor to look at a body. His daughter’s remains were badly decomposed, but he recognized her clothes.

It would be up to Dr. Moritz and the Harvard forensic scientists to make a positive identification, using evidence they’d gathered from the crime scene and her body. They’d also be tasked with solving a series of mysteries that stacked like nesting dolls.

When did Perry die and where?

How was the murder committed and who was the culprit?

And why would anyone want to kill Irene Perry in the first place?

LEE DIDN’T KNOW anything about living a life as hard as Perry’s, but she knew what it was like to be a woman in the early 20th century. How the wishes of a girl’s parents, and then a woman’s husband, could circumscribe a life. What it was like to dream of a new start in a new place. How it felt to be looked down upon.

“Chief amongst the difficulties I have had to meet,” Lee once wrote in a private letter, “have been the facts that I never went to school, that I had no [professional degree] letters after my name, and that I was placed in the category of ‘rich woman who didn’t have enough to do.’”

Still, Lee had a preternatural ability to prevail when people made the mistake of underestimating her, including in the halls of Harvard Medical School, which didn’t admit female students until 1945 .

In 1935, she decided the department of legal medicine needed more office space, training her eye on a set of offices occupied by the pharmacology department. When her written request to the dean for that space was rebuffed, she took her case to Harvard’s president — he also resisted.

She waited three months and then wrote to the president again. “I do not feel that I can let our decision pass without a protest,” she wrote, “and request that you give this problem a little further study.”

She got the office space.

Lee tangled with medical school leaders in other ways, including over priorities for the department. She believed Harvard should play a larger role in training police officers, so they could improve their ability to spot clues at crime scenes and gather and protect evidence for medical examiners. But Harvard leaders were more focused on research and teaching — plus, they found assisting the local police expensive — and largely dismissed the police work she supported.

Lee had a theory about one of the reasons why. “Men are dubious of an elderly woman with a cause,” she observed. “My problem is to convince them that I am not trying to butt in or run anything. Also, I have to sell them on the fact that I know what I am talking about.”

As Lee pushed for change, in Massachusetts and across the nation, she tapped influential people. She once arranged a meeting with FBI director J. Edgar Hoover to discuss forensic medicine. And she developed a close relationship with Malden-born Erle Stanley Gardner , author of The Case of the Fenced In Woman and other Perry Mason mysteries. He’d become a booster of her cause, and dedicate a novel to her.

Lee’s goal was to eliminate human bias from death investigations. “[F]ar too often the investigator ‘has a hunch,’ and looks for and finds only the evidence to support it, disregarding any other evidence that may be present,” she wrote in an article for a criminology journal. “This attitude would be calamitous in investigating an actual case.”

FOR NEARLY TWO WEEKS after Irene Perry’s body was discovered, Dr. Moritz and his colleagues at the department of legal medicine worked feverishly. This was one of the new department’s first major cases, and Lee knew high-profile investigations could demonstrate the importance of forensic medicine across the country.

To understand the circumstances of Perry’s death, the scientists would need to summon all the disciplines at their disposal, including medicine, chemistry, entomology, and botany.

Moritz confirmed the body was Perry. In addition to her clothing, everything else matched: her height (about 5-foot-2), her estimated weight (100 to 110 pounds), and her short brown hair. Dental characteristics made it certain.

A key question was this: Did Perry die the night of June 29, 1940, when she disappeared, or days or weeks later? The answer could help police rule out suspects — or identify a killer.

At the crime scene in Dartmouth, the scientists found that the plants trapped beneath Perry’s body, including lowbush blueberries, had reached full leaf — and then abruptly stopped growing. Considering when that stage was reached for that species, her body must have been left there sometime after June 15. Meanwhile, the insect larvae found on Perry were in a stage of development that put her time of death at four or more weeks before she was found. Combining this analysis with the date of Perry’s disappearance pointed to a time of death very close to when she was last seen.

Moritz knew the heavy rope found wrapped around the victim’s neck and wrists required careful observation.

To determine if Perry was strangled to death, he measured the first loop of rope around her neck. It was 10.5 inches. That was likely tight enough to kill her, but her neck was so decomposed Moritz couldn’t be sure. He assembled 50 female volunteers between the ages of 18 and 25, so he could measure their necks. None had a neck circumference less than 12.5 inches.

When Moritz and his staff tightened a rope on the necks of these volunteers, they found merely a half-inch caused “great discomfort,” and 3/4 inch “could not be tolerated.” The evidence showed Perry was a “victim of homicidal strangulation,” Moritz wrote in his report.

A close examination of Perry’s skeletal remains yielded one last surprising finding: Fetal bones. At the time of death, Perry was pregnant with her second child.

“Irene Perry was unmarried,” Moritz wrote in his report, issued on August 10. “The finding of the bones of an unborn three month old fetus in the abdominal cavity of the dead woman provides a possible motive for her death.”

In the understated tone of a scientist, he noted a new avenue deserving of inquiry: “The desirability of attempting to learn the identity of the man responsible for her pregnancy is obvious.”

ON THE NIGHT of August 26, police arrested Frank Pedro, a 25-year-old New Bedford laborer, and charged him with murder. They had interviewed dozens of people, and finally zeroed in on Pedro because of the unique characteristics of the rope in the murder.

Investigators had traced it to a manufacturer in New York, where a strand of rope had been accidentally made with 24 threads, rather than the usual 21. After that manufacturing mistake, the rope was trucked to a Long Island wholesaler, and then to a job site at an estate in Rhode Island where Pedro’s relative worked. The same rope — the same 24 threads — was found in Pedro’s basement, police said.

The forensic scientists and police had uncovered the evidence. The rest was up to the legal system of the day.

Reporters were in the Bristol County Superior courthouse in May 1941, when Pedro’s trial began. Newspapers had been covering every unseemly twist of the case, drawing an increasingly unsympathetic picture of a promiscuous young woman, one who’d had her first child out of wedlock and was pregnant with another. Records show lawyers were concerned potential jurors might be swayed by the salacious details they’d read.

Judge Walter Collins presided over the trial, swearing in 12 jurors that would ultimately decide if the defendant was guilty. As was customary at the time, it would be limited to men — women in Massachusetts were barred from sitting on criminal juries until the 1950s.

Prosecutors outlined their case: Perry’s murder was likely committed shortly after her disappearance on June 29, 1940, and at some place between her home and the rifle range. She was killed somewhere else, then dragged into the woods. Dr. Moritz was called to the stand, testifying that “the probable cause of death was strangulation.”

The rope found in Pedro’s cellar and around Perry’s neck “were identical in every respect,” a police captain said from the witness stand.

Prosecutors also pointed to the motive. Pedro was a married man, with a baby boy at home. He’d admitted during police questioning that he had been romantically involved with Perry for several years — that he had “illicit relations with the girl over an extended period,” in the words of a news story. They’d even gone parking near Lovers’ Lane, he admitted, in the area where Perry’s body was discovered.

The forensic evidence and the police interviews appeared strong. When court-appointed defense lawyer Samuel Barnett began his interrogations, however, he worked to introduce doubt into key aspects of the government’s case.

Barnett put Pedro on the stand to profess his innocence. He told jurors that he’d ended his relationship with Perry some months before her murder, in March 1940, because he was married, had a child, and, as he put it, “didn’t want trouble with his wife.” Pedro insisted Perry never told him she was pregnant.

Barnett called his own rope specialist to the stand, who said the piece in Pedro’s house was different from the type found around Perry’s neck. In fact, Barnett disputed that Perry had been strangled to death at all. What if the scene was staged to look that way?

Barnett presented another theory that had the potential to turn the jury against Perry. The victim, he suggested, may have died from an “attempted illegal surgery” — a reference to a botched abortion — that was later covered up to look like a murder, perhaps by whoever performed the procedure.

After hearing testimony over two weeks, the jury deliberated for less than two hours. Foreman Frederick Kerry, a Taunton shop owner, delivered the verdict: “Not guilty.”

RECORDS DON’T SHOW if Lee and the Harvard experts were surprised by the verdict, or if law enforcement thought a guilty man went free. Perry’s name disappeared from the headlines. Her son, Donald, would be raised by her extended family.

But in the months that followed, Lee plunged with obsessive energy into a massive, multiyear project largely focused on deaths like Perry’s. It would combine Lee’s childhood training in the “women’s work” of sewing and crafting with her later-life passion for crime scene investigation.

She created 18 immensely detailed, dollhouse-like dioramas of crime scenes. But these were not toys. They were tools to train detectives. To come up with her scenarios, Lee studied real life case files and police photographs.

“My whole object,” she once explained, “has been to improve the administration of justice, to standardize the methods, to sharpen the existing tools as well as to supply new tools, and to make it easier for the law enforcement officers to ‘do a good job’ and to give the public ‘a square deal.’”

Lee called them The Nutshell Studies of Unexplained Death , after a police saying: “Convict the guilty, clear the innocent, and find the truth in a nutshell.” The point was to learn to look closely at the evidence.

In a miniature bathroom scene, a woman is dead in a bathtub, her stiff legs splayed out and water running over her face. Did she have an accident? Or did the rigor mortis in her legs suggest she was killed elsewhere and moved into the tub? In a kitchen, a dead woman lies near an open oven door. Was this a case of suicide due to the gas or a clever imitation? At the scene of a fire evidence pointed toward the blaze starting beneath the wife’s bed. Was the husband capable of murder?

Lee spared no time or expense in making her nutshells, spending months and as much as $135,000 in today’s money on each. She personally made many of the items within the crime scenes, working with her carpenter in New Hampshire. Tiny pencils contained real lead, a police whistle can emit a shriek, and one room had a miniature Sherlock Holmes novel.

The minutely detailed models didn’t portray the elegant spaces of Lee’s own life — the mansions, the Ritz, the Chicago Symphony — but environments where working-class people lived and died, predominantly women. Lee is unlikely to have used the word feminist to describe herself, her biographers say, yet her dioramas often seem to point to the oppressed place of women in society.

If she died by suicide, why did she do it in the middle of making dinner? There is a cake in the oven and half-peeled potatoes.

The beverage at the table suggests someone was sitting there, possibly the murderer who staged a suicide ? Was the ice cube tray in her hand a sign of her serving a beverage ?

The gas jets on the stove are open, the kitchen door is sealed shut, and her face shows a rosy hue suggesting she died of carbon monoxide poisoning.

“Her actions were much louder than her words,” says Susan Marks , a documentary filmmaker whose second film about Lee’s life will be screened in October at The Rocks estate. “Her actions were very much that women’s voices had to be heard.” In making the dioramas, Marks continues, “She chose quite a few situations in which women are murdered, including in places where they are supposed to be safe.”

Lee’s carpenter helped with construction, but Lee insisted on creating the victims herself. She took immense care with them, knitting tiny stockings with straight pins, placing a knife in a woman’s chest, painting a face in the precise shade of red indicative of carbon-monoxide poisoning.

It’s not a coincidence that Lee’s murder scenes are often set in kitchens, bedrooms, and living rooms, explains Corinne May Botz , a photographer and author of the book The Nutshell Studies of Unexplained Death. “The nutshells can be viewed as precursors to the women’s movement,” she writes, “because they depict the isolation of women in the home and expose the violence that originates and is enacted there.”

The nutshell studies would become the centerpiece teaching tool of one of Lee’s most lasting legacies: One-week seminars designed to teach state and local police officers from across the country about medical forensics. The seminars would include presentations from experts on the latest advances in criminology, then conclude with training on her nutshell studies.

Lee presided over her invitation-only annual seminars like a regal chairwoman. They included a multi-course banquet at the Ritz with elaborate flowers arranged by Lee herself. The hotel spent thousands of dollars on gold-leaf dinnerware to be reserved only for the seminars, at her insistence. (She was “probably the fussiest patron the hotel ever had,” the general manager later said, “and we loved her.”)

One year, Lee allowed her friend Gardner, the novelist, to attend one of her seminars. Lee’s instructors accomplished feats of deduction “little short of astounding,” he wrote, and said students could learn more from her crime scenes in an hour than in “months of abstract study.”

Gardner would never dare put one of Lee’s graduates in one of his novels, he noted — that detective would solve the mystery a hundred or so pages before Perry Mason.

IN THE SUMMER OF 1946, Lee’s nutshell studies captured the attention of an editor at Life magazine, which published photos and an article about them. That story, in turn, caught the eye of filmmakers at Metro-Goldwyn-Mayer .

The MGM executives reached out to Lee and Moritz, suggesting a film about the Harvard department. They offered a working title, Murder at Harvard, and submitted a draft script that featured “Mrs. Lee” as a central figure in improving the way homicide investigations were handled.

“Confirming our telephone conversations,” MGM’s Samuel Marx wrote to her in February 1948, “we feel that an interesting motion picture of a semi-documentary nature can be made dealing with your work in the field of crime.”

Lee was pleased her department was gaining notice, but never liked lavish amounts of media attention on her. She wanted the department’s work on behalf of the public to take center stage. When meeting with MGM, she said she had just the right story to focus on. It was a murder case she hadn’t been able to forget, even nearly a decade after it ended without justice for the victim.

Don’t focus on me, Lee said. Focus on the Irene Perry case.

The Hollywood executive listened.

“After our very pleasant dinner,” Marx wrote Lee later in 1948, “I went to New Bedford, Massachusetts, and investigated the Irene Perry case in which the Department of Legal Medicine played such an important part of the solution.”

The script was written and the movie went into production.

BY 1949, THE HARVARD department of legal medicine was weakening. Dr. Moritz left Harvard to head a pathology center in Cleveland, and remained influential in the field. After President John F. Kennedy’s assassination, he gave expert testimony on the autopsy.

Moritz’s replacement struggled to run the program with a firm hand. “In my opinion,” Lee wrote, “the Department is rapidly dying on its feet.”

In the years to come, she worked hard to get the medical examiner system adopted in more states, but found local resistance throughout the country. She also struggled with serious medical issues, including breast cancer. Her fears about mortality caused her to be more open about some of the challenges — especially as a woman — that she faced in her work.

“For me, it has been a long, discouraging struggle against petty jealousies, crass stupidities, and an obstinate unwillingness to learn that has required all the enthusiasm, patience, courage, and tact that I could muster,” she wrote to her trusted advisers. “Also, being a woman has made it difficult at times to make the men believe in the project I was furthering.”

She appeared to reserve her harshest criticism for Harvard, saying it had a deserved reputation of being “old fogeyish and ungrateful and stupid.” She decided in the end against giving the school any money in her will, and urged her advisers to monitor her previous gifts closely. “Harvard is clever and sly and will need to be watched constantly or she will take advantage of you and apply any funds you may grant her to her own purposes,” she wrote.

In 1962, at age 83, Lee died of complications from cancer. She was buried at Maple Street Cemetery in Bethlehem, New Hampshire. At The Rocks, a few miles away, the state installed a historical marker calling her the “mother of forensic science.”

Some of her fears about Harvard soon began coming true. The university shuttered the department of legal medicine in 1966, and her nutshell studies were handed over — ”on loan for an indefinite period,” says a university spokesman — to the Maryland medical examiner’s office, which had close ties with Lee. The Magrath library was folded into the main one at the medical school. The professorship she’d endowed sat vacant for many years, and for the last two decades the position has focused on bioethics.

If the victim was trying to sober up, wouldn’t she have used the sink rather than turned on the tap of the tub?

Was she drinking alone and passed out? Is it possible she drank with a guest?

The woman’s legs show rigor mortis. Was she killed elsewhere and moved here?

Was she drinking alone and passed out? Did she drink with a guest?

When the Smithsonian American Art Museum in Washington, D.C., opened an exhibit of Lee’s nutshell studies in 2017, some Harvard physicians broached the idea of bringing the dioramas to a Boston museum. But the proposal got mired in questions of logistics, and still-unresolved legal issues over who actually controls them.

The Maryland medical examiner’s office, however, has continued Lee’s tradition of holding the homicide training seminars. This year’s installment , in October, will include expert-led sessions on strangulation, poisoning, and other causes of death. As is customary, the program will feature investigations of Lee’s nutshells.

Lee’s files at Harvard are full of letters from medical examiners and police officers from across the country, saying they are deeply indebted to her for making them more observant detectives, even as the field of forensics has come to include DNA analysis and other advances she never could have dreamed of.

“This was the essence of Frances Glessner Lee,” says Thomas Andrew, a former chief medical examiner in New Hampshire. “Look at what the scene tells us.”

IRENE PERRY WAS BURIED at New Bedford’s St. John the Baptist Cemetery, in an unmarked grave that is numbered 976.

Helen Craig, now 79, is Irene’s only surviving sibling, the child of Irene’s father and his second wife. She tries sometimes to visit her half-sister’s grave. She says her father spoke little of Irene’s death, but understands why. “He was heartbroken by it,” she says.

Relatives say Perry — and her murder — were almost never openly discussed at family gatherings, and some surmise it was because her case had the whiff of scandal. “Nobody talked about it,” says Charles Lackie, a retired Dartmouth police sergeant whose grandmother was Perry’s sister. “It’s like it never happened.”

But for those who look closely, Irene Perry’s death and life are memorialized in a different way. MGM had followed Lee’s advice, and focused not on her, but on the case of a working-class woman from an immigrant family in New Bedford.

“Irene Perry’s case is exactly the kind of death that would have been overlooked,” says Goldfarb, Lee’s biographer, “if not for Lee’s determination that all victims, regardless of their background, receive rigorous investigations.”

Renamed Mystery Street , the film premiered nationwide in 1950, receiving many positive reviews. Starring a young Ricardo Montalban as a detective from the local Portuguese community, it was the first forensic-science procedural put to film. It was also the first commercial movie filmed in Boston, with scenes of Beacon Hill and Harvard Square. (The original title, Murder at Harvard, was changed after the university complained it would sully its brand.)

Although Mystery Street is fictionalized — the victim isn’t a dark-haired woman named Irene, but a blonde named Vivian — it includes many similarities to the Perry case. The skeletal remains of a young Massachusetts woman are discovered in a remote area, and the killer remains on the loose. Harvard pathologists led by Dr. McAdoo, modeled on Dr. Moritz, use forensics to establish the facts of her murder. When examining her skeleton, they find the tiny bones of a fetus.

The biggest difference may be that, in the movies, the Perry character gets the Hollywood ending that no amount of forensic science could deliver her in real life. Though police initially apprehend the wrong man, they successfully chase down the real killer. He’s a married man, a father, and had been the victim’s lover. After she confronted him about ignoring her, saying she was “in a jam,” he shot her.

The movie also portrays the hard life of single working women at the time, struggling to pay rent and seeing relationships with men as one way to gain stability in their lives. It is Vivian’s boarding house roommate, Jackie, who first reports to police that she has mysteriously disappeared. Jackie worries something terrible has happened to her.

When investigators interview her, she reflects on how hard life could be for women like her and Vivian.

“Girls like us,” she says. “Mostly there’s nobody to look out for us.”

Patricia Wen can be reached at [email protected] . Follow her @GlobePatty .