How much bounce a ball keeps after each impact is what the coefficient of restitution measures. To rank tennis balls by this property, drop five balls of each brand from one meter and count the bounces. More bounces mean the ball returns more energy after hitting the surface — a higher coefficient of restitution. Then launch the same balls from a tennis ball launcher on an open field and measure how far each one travels. Softer balls bounce more and tend to fly farther from the launcher, linking retained bounce directly to distance.

A bouncier golf ball keeps more energy after hitting the surface — and that retained energy may translate into longer drives. To test this, drop three brands of golf balls from one meter onto a flat surface and count the bounces. This ranks their bounciness. Then bring three amateur golfers to a driving range and measure how far each ball travels when hit with a driver. Comparing bounciness rankings to driving distance shows whether the springiest ball really does fly the farthest.