Why Things Bounce

When you drop a rubber ball, it hits the ground and bounces right back up. This happens because the ball is elastic. When it hits the ground, it squishes slightly and stores energy. Then it springs back to its original shape and releases that energy, pushing itself upward. Not all materials bounce equally well.

Elastic and Inelastic Bouncing

A rubber ball bounces well because rubber is very elastic. It squishes and springs back easily. A ball of clay does not bounce because it is not elastic. When it hits the ground, it just flattens and stays flat. The energy goes into changing the clay's shape instead of bouncing it back up.

Energy and Bouncing

A bouncing ball never bounces back to its original height. Each bounce is a little lower. This is because some energy is lost as heat and sound with each bounce. The thump you hear when a ball hits the ground is energy leaving as sound. Eventually the ball loses all its bouncing energy and stops.

Fun Facts

• A super ball can bounce to about 90 percent of the height it was dropped from.
• Basketballs are inflated to a specific pressure so they bounce to a standard height.
• The bounciest material ever made can bounce to 97 percent of its drop height.

Did You Know?

If you drop a tennis ball on top of a basketball and they hit the ground together, the tennis ball rockets much higher than if dropped alone. The basketball transfers its energy to the tennis ball in a super bounce effect!