PHYSICS: Potential Energy

Potential energy exits whenever an object which has mass has a position within a force field. An object can store energy as the result of its position. Potential energy is the stored energy of position possessed by an object.

Gravitational Potential Energy

-         Is the energy stored in an object as the result of its vertical position or height. The gravitational potential energy of the massive ball of a demolition machine is dependent on two variables – the mass of the ball and the height to which it is raised. There is a direct relation between gravitational potential energy and the mass of an object. More massive objects have greater gravitational potential energy. There is also a direct relation between gravitational potential energy and the height of an object. The higher that an object is elevated, the greater the gravitational potential energy. These relationships are expressed by the following equation:

m = mass of the object

h = height of the object

g = gravitational field strength (9.8 N/kg)

Elastic Potential Energy

-         Is the energy stored in elastic materials as the result of their stretching or compressing. The amount of elastic potential energy stored in such a device is related to the amount of stretch of the device – the more stretch, the more stored energy.

Springs are a special instance of a device that can store elastic potential energy due to either compression or stretching. A force is required to compress a spring; the more compression there is, the more force that is required to compress it further. For certain springs, the amount of force is directly proportional to the amount of stretch or compression (x); the constant of proportionality is known as the spring constant (k).

Such spring are said to follow Hooke’s law. If a spring is not stretched or compressed, then there is no elastic potential energy stored in it. The spring is said to be at its equilibrium position. The equilibrium position is the position that the spring naturally assumes when there is no force applied to it. In terms of potential energy, the equilibrium position could be called the zero-potential energy position. There is a special equation for springs that relates the amount of elastic potential energy to the amount of stretch (or compression) and the spring constant. The equation is:

k = spring constant

x = amount of compression

(relative to equilibrium position)

Source: www.physicsclassroom.com/class/energy/