Each student should be given a ball to drop from a height h of one meter and measure the distance d to which it bounces upward. The results should be arranged according to the types of balls and the group should discuss which balls bounce well, and why. If there is time, a given ball should be allowed to bounce several times after being released from an initial height h . The ball begins at rest from height h with potential energy mgh , where m is its mass and g is the acceleration due to gravity. On first bounce it comes up to a height d , corresponding to potential energy mgd .
Energy is dissipated in the form of heat and acoustical energy.
Physicists believe in the principle of conservation of energy as a consequence of the symmetry of the basic interaction under translations in the time coordinate. Bounce a ball across the room to an assistant so that it strikes the floor several times. Have each student draw the trajectory of the ball in the notebook, describing its motion as completely as possible. A ball bounced off a hard surface loses a specific fraction of its mechanical energy with each bounce. The bouncing of a ball on a hard surface is essential for an understanding of baseball, which is played with gusto in Asia, Latin America, the Caribbean Region, and North America.