What You Need:

• Freezer
• Two identical tennis balls
• Plastic bag
• Video Camera (optional)

What To Do:

1. Place one of the rubber balls into a plastic bag and place the bag into the freezer. Keep the other ball in a warm place like your pocket.
2. After a few hours, bounce both balls at the same time and compare their bounce. If you have a video camera handy you could ask someone to record you bouncing as this will make it easier for you to see.
3. You should find that the warm ball bounces slightly higher. The cold ball should bounce about 80% as high.

What’s Going On:

The materials in the balls are made up of long stretchy polymers. Normally when you drop the ball its molecules are stretched when it hits the floor and the ball is slightly deformed. After a moment, the molecules return to their original position causing the ball to bounce upwards. When the ball is frozen the polymers are less pliable and this makes the ball less bouncy.

Photo Credit: DaDaAce