A tennis ball bouncing on a hard surface compresses and then rebounds. The details of the rebound are specified in tennis regulations. Tennis balls, to be acceptable for tournament play, must have a mass of 57. 5 g. When dropped from a height of 2. 5 m onto a concrete surface, a ball must rebound to a height of 1. 4 m. During impact, the ball compresses by approximately 6 mm.