Circles and Force

In this blog entry we share 4 fun lessons to help children understand force. Each lesson builds on the last and becomes progressively more complex. Our first lesson is appropriate for age 2+. Our second lesson can be completed by anyone who is learning to read and measure. Our third lesson is for the kids who love big words and hands-on crafts. Our fourth lesson is for anyone who is ready to push their limits.

Here is an image of a circle with the words: "Circles and Force'

Lesson #1: Play

Visit a park. Experience pushing and riding on a Merry-go-round. Feel everything about the experience. Stand at the center of the circle and on the edges of the circle. See if it feels different. Notice how much more strength you need when you push more people on the merry-go-round. Throw around the terms circle, spin, radius, force, mass, speed, velocity, and maybe have fun trying to pronounce centrifugal force. 

Picture of children spinning on a modern merry-go-round at a park. One child pushes (while jumping) and another rides.

When we returned from the park, we listened to a "Moment of Science" episode with an explanation of centripetal force. https://indianapublicmedia.org/amomentofscience/centripetal-force-and-merry-go-rounds.php

The next morning, the children built their own merry-go-round out of LEGO. Then they loaded it up with figures and explained how the figures feel when they spin.  Here is a photo.

Here is a link to the video they made, on YouTube:

https://youtu.be/4PnjVil0HxE

Lesson #2: Spinning circles

Find a circle. Measure the radius. Spin the circle. How much force did you use? Find a bigger circle. Is it heavier? Do you use more force to spin it? 

Words to learn: circle, radius, spin, force. A measuring tape or ruler should be provided so the student can take measurements.

Each word is written using two colors: blue for consonants and red for vowels.

You can find circles and spin them all afternoon. Do you have a toy top? This might be a great time to bring it out to play, too. Talk about their size and weight. Look at their materials and note how smoothly they move across various surfaces. 

Keep using those new words like radius and spin until they are easy.

Lesson 3:  Merry-go-round

Are you the one making it spin? You exert centripetal force. Are you spinning? You experience centrifugal force.

Words to learn: spin, force, centripetal, centrifugal. 

Make your own merry-go-round with materials you have available. In the example here, we used a spool of ribbon and a marker, but you can use literally anything. Find someone or something that is the right size to ride on the merry-go-round. We used a figurine. Remember lesson #1, when you rode on and pushed friends on a merry-go-round. Think about what it felt like when you had each role. 

Use those new big words as you describe your work. It's an opportunity to joke as you mess them up the first few times. Get comfortable with saying them yourself and the children will, too.

Lesson #4: Advanced

Here we skip ahead a few grades to a lesson that requires algebraic math skills. This is presented in a way that was easy to explain to my oldest child.

 Prerequisite skills:

- confident with seeing a formula and plugging in numbers

- familiar with exponents

- enjoys word problems

- knows about negative numbers and absolute value

If your child has these skills, it's time for this lesson. If not, hold off. Take a bit more time and work up to it. 

Use the formula provided. How much force do you need to exert to spend five people who weigh 20 kg each at a speed of 1 m/s on a circle that is 1 m from center to edge? Will you use centripetal or centrifugal force to push them? Which force will they feel as they ride? 

Centripetal and centrifugal are opposites. They have the same absolute value, but are on opposite sides of 0 on a number line. What is the centrifugal force for this problem?

Plug in other numbers and think up other scenarios. How would this change if you had a smaller circle or a heavier person riding? 

Here are photos of our children interacting with this series of lessons today.

Conclusion: Personal note

Physics problems like these stumped me in high school and the first bit of college. When I finally understood, I realized presentation was everything. Active, hands-on learning was what I needed. Once it clicked for me, I realized I could introduce these concepts to much younger people. 

I love engaging in creative learning alongside the children in my life. These lessons are a natural extension of our playtime.

I hope you have fun with this lesson, too! 

Related Lessons:

Here is a lesson about aerodynamics and rocket design:

http://steamma.blogspot.com/2021/11/ball-play.html?m=1

Here is a link to a lesson where we discuss velocity, as it relates to cars: https://steamma.blogspot.com/2021/06/8th-annual-car-show.html?m=1