Science for Kids/kinetic/potential energy
What does the law of conservation of energy state?
Energy cannot be created nor destroyed.
For example, if you have a baseball in your hand and you drop it to the floor, it loses the mechanical potential energy due to its height, but once it's sitting on the floor, that energy isn't totally gone - it has turned into heat energy of friction from hitting the floor and bouncing. Another example is passing electricity through a light bulb. The electric energy turns into light and heat.