Bouncing balls: what is elasticity
Three balls fall from the same height but bounce differently. A simple physics experiment for kids 5+: elasticity, energy and rebound.
Press “Run”. Bodies move by the laws of physics: gravity, friction, elasticity.
What the experiment shows
Three equally sized balls drop from the same height. Each has its own elasticity: the “clay” ball barely bounces, while the “rubber” ball rises almost back to where it started.
How to run it
- Press “Run” and watch the balls.
- Press “Reset” and run it again, counting the bounces of each ball out loud.
- Open the example in the editor and set the middle ball’s restitution to 0.9.
Questions to discuss
- Which ball bounced the highest? Why do you think so?
- What happens if you drop the ball from a higher place?
The science
On impact some of the ball’s energy turns into heat and deformation, and some returns as motion. The returned share is the elasticity (coefficient of restitution). The closer it is to 1, the higher the bounce. Gravity pulls every ball the same way, so they all fall with the same acceleration of 9.8 m/s².
Try it at home
Take a tennis ball, a rubber ball and a ball of clay. Drop them from the same height onto the floor and compare the bounce. Children can mark the rebound heights with stickers on the wall.
What to change in the editor
- Change the balls’ mass — does the bounce change?
- Set the frame gravity to 1.6 (like on the Moon).