Have you ever stretched a rubber band and let it go? When you stretch a rubber band it stores a type of potential energy. When you release it, all that stored energy has to go somewhere. When you launch your rubber band across the room (or at someone), the potential energy is converted to kinetic energy or the energy of motion.
Similarly when you wind up the car’s axle you stretch the rubber band and store potential energy. When you release it, the rubber band starts to unwind, and the potential energy is converted to kinetic energy or movement as the car is propelled forward. The more you stretch the rubber band, the more potential energy is stored, and the farther and faster the car should go.
Potential energy is stored energy from an object. Instead of coming from motion, it can come from its position relative to others, internal stress, electric charge, or its condition. This object has the capability of producing energy as these conditions change. This energy could be mechanical energy, chemical energy, electric energy, nuclear energy, or magnetic energy.
Mechanical energy is the energy of movement. All items have potential energy based on their position (gravitational potential energy) and ability to bounce (elastic potential energy). When the potential energy of an object is combined with its kinetic energy, it results in mechanical energy.
When something has a high position, its gravitational potential energy is high. For example, a book on a high bookshelf has higher potential energy than a book on the bottom shelf because it has farther to fall. Other examples of items with gravitational potential energy include:
A raised weight
Water that is behind a dam
A car that is parked at the top of a hill
A yoyo before it is released
River water at the top of a waterfall
A book on a table before it falls
A child at the top of a slide
Ripe fruit before it falls
The material an item is made of can affect its potential energy as well. An elastic ball has higher elasticity than a bowling ball; therefore, it will bounce higher with the same amount of force. Here are some more examples of items with elastic potential energy.
A coiled spring
An archer's bow with the string pulled back
A stretched rubber band
Soccer Balls before players kick them
A diving board just before someone dives