Hot and Cold Basketballs

Will a basketball bounce higher when warm or cold?
- Lance (age 13)
RED OAK, NC

The ball bounces well when nearly all the energy it has as it falls is returned to it as it bounces up. The main other place that energy can go is into heating up the plastic, which flexes as the ball compresses during the bounce. When it flexes, the molecules sort of rub against each other, and some of the energy flows via friction into little molecular jiggles, or heat. Whether the plastic does this more when it’s hot or cold depends on the particular plastic and other details. What’s more important is that when the ball is hot, the air pressure inside is bigger, so the ball is less squishy and the plastic doesn’t flex as much during a bounce. So we bet that the hot ball bounces better, but the best way to be sure is to try it.

Mike W.  and Tom J.

(published on 10/22/2007)