Potential energy:

 Potential energy is energy stored within a physical system as a result of the position or configuration of the different parts of that system. The potential to be converted into other forms of energy, such as kinetic energy, and to do work in the process. The SI unit of measure for energy and work is the joule (symbol J).Potential energy is the same as stored energy. The stored energy is held within gravitational field. When you lift a heavy object you exert energy which will become kinetic energy later when the object is dropped. Potential energy is energy which is stored within a system. It exists when there is a force which tends to pull an object back towards some lower energy position. This force is often called a restoring force. For instance, when a spring is stretched to the left, it exerts a force to the right so as to return to its original, unstretched position. Likewise, when a mass is lifted up, the force of gravity will act so as to bring it back down. The initial actions of stretching the spring or lifting the mass both require energy to perform. The energy that went into lifting up the mass is stored in its position in gravitational field, while similarly, the energy it took to stretch spring is stored in metal.

 In accordance to the law of conservation of energy, energy cannot be created or destroyed; therefore this energy cannot disappear. Instead of that, it is stored as potential energy. If the spring is released or the mass is dropped, this stored energy will be converted in kinetic energy by the restoring force, which is elasticity in the case of the spring, and gravity in the case of the mass. Think of the roller coaster. When the coaster climbs a hill it has potential energy. At the top of the hill is its maximum potential energy. When the car speeds down the hill potential energy turns into the kinetic. Kinetic energy is largest at the bottom.

There are several types of potential energy, each associated with a particular type of force. Specifically, every conservative force gives rise to the potential energy.

Electric potential energy, or electrostatic potential energy, is the potential energy associated with conservative Coulomb forces within the defined of point charges.

 Gravitational potential energy is the energy stored in an object as a result of the vertical position or height. The energy is stored as a result of the gravitational attraction of the Earth for object. The gravitational potential energy of the massive ball of a demolition machine is dependent on 2 variables - the mass of the ball and the height to which it is raised. There is a direct relation between potential gravitational energy and the mass of an object. More massive objects have larger gravitational potential energy. There is a direct relation between potential gravitational energy and the height of an object.

As the gravitational potential energy of an object is directly proportional to its height above zero position, a doubling of the height will result in a doubling of gravitational potential energy. A tripling of height will result in a tripling of gravitational potential energy.