To understand the law of conservation of energy using a simple experiment.
1. A tennis ball.
2. A knife.
Procedure of the project:
1. Drop the tennis ball from a height on to the floor. Simply drop and do not throw it. Observe how the ball bounces back but not quite up to the point from which it was dropped.
2. Now use the knife to cut the tennis ball into two hemispheres. The trim the halves so that each one is a little smaller than a hemisphere.
3. Turn one half inside out and drop it from a height. You will see that half ball rebounds higher than the point from which it was dropped.
When the ball is dropped, it does not rebound up to the initial height due to the effect of the law of conservation of energy which states that energy can neither be created nor destroyed, but only changed from one form to another. When the ball is held at a height, it has potential energy. When it is dropped and it hits the ground, this potential energy is converted into kinetic energy of motion and some amount of heat upon hitting the ground. As some energy is lost as heat, the kinetic energy of the ball is not as much as the earlier potential energy. Hence it does not rebound quite up to the dropping point. Now when the half of the ball is turned inside out, the energy required to turn it inside out is stored as potential energy in the ball. When the half ball hits the ground this potential energy is released and changed to kinetic energy. Therefore the half ball rebounds higher than the point from which it was dropped. The law of conservation of energy is still obeyed in this case.