Under Pressure: Ball Bouncing Dynamics
Ask any sports enthusiast and they'll readily recall that many popular sports make use of a ball in some way, shape, or form. Speaking specifically of sports balls that are filled with air - basketballs, footballs, volleyballs, etc. - have you ever wondered, why, when you kick, hit, throw, or bounce it, it bounces right back? Dr. Sara Agee, Science Buddiesproject designer, has created a sports science experiment that explores just that - specifically, the significance of air pressure and ball bouncing dynamics!
The Basics of Ball Bouncing
- When a ball is dropped, gravity pulls it toward the ground.
- The energy of motion - known as kinetic energy - builds as the ball is pulled to the floor.
- When the moving ball hits the floor (or another surface), the kinetic energy is displaced, causing the natural shape of the ball to be deformed/flattened.
- The air molecules within the ball first compress, then "spring apart" - causing the ball to rebound or bounce back.
Here are a few videos that show the compression of a moving ball when it hits a rigid surface:
In this project designed for grades K-5, students will explore how changing the air pressure in a ball will affect its 'bounciness'. Students, using an air pump and pressure gauge (perhaps with the help of an adult0, will prepare basketballs of different pressures and perform bounce tests, recording the balls height at the top of the arc of the first bounce for comparison. By graphing these results, students will get a good picture as to how air pressure affects bounce.
For a list of materials and supplies, step-by-step instructions, helpful resources, experiment tables, and project variations, be sure to check out the project page at Science Buddies!