During a bounce, a basketball stores some of its kinetic or motional energy in its dented surface. The ball and floor dent one another inward and this denting involves physical work-the transfer of energy from one place to another. The ball and floor lose speed relative to one another and their elastic surfaces are packed with extra energy. As the ball rebounds, the two surfaces undent and return some of this stored energy to the ball's motion.
How efficiently the ball stores energy depends on many factors, particularly the amount of air it contains. A poorly inflated basketball bounces weakly because its surface dents easily and its leathery skin wastes a great deal of energy through internal friction. A tautly inflated basketball dents very little and stores energy efficiently in the compressed air inside it.
Air is a factor in basketball. Why do you think they call Michael, "Air Jordan"?
Answered by Lou A. Bloomfield of the University of Virginia