Ask Jimmy and the Bug

Jimmy and the Bug
there is a picture of Jimmy, catching a ball.

Hey Bug! Natalie K. from Illinois wants to know: What makes a bouncy ball bounce?

When you drop a ball, the ball pushes down on the floor and the floor pushes back up on the ball. (Weird!) In slow motion you would see that the side of the ball squishes or dents when it hits the floor. According to physics professor Lou Bloomfield, the energy of the falling ball is now stored in the dented ball. The ball then uses that energy to push back on the floor. It undents—and bounces.

there is a drawing of Jimmy flushing the toilet.
There is a picture of Jimmy doing the dishes.

The ball doesn't bounce back as high as it fell because it cannot store all the energy it had when it hit the ground. Some of that energy is lost to heat. That's why a basketball warms up when you dribble it. Bounciness depends upon what a ball is made of and how it's put together. In a “Bounciness Olympics,” superballs would take the gold. Made from a special hard rubber, superballs return to their original shape when dented without losing too much energy. Most hard surfaces store and release energy better than soft ones. That's why beanbags don't bounce very well and why rubber balls bounce higher on cement than on carpet. Now, when you're told the living room is a bad place to play ball, you'll know why.


  1. Imagine you threw a superball in a kitchen. The superball bounces eight times before it comes to a stop. What is the location of the ball in the kitchen each time it bounces? Use the place and location words you read about in Lesson 1 to describe each place the ball bounces before it stops. Draw a diagram to show the path of the ball as it bounces through the kitchen.