The Concept of Potential EnergyIt is the energy possessed by a body by virtue of the position in a field of force or by its configuration.
A few examples from our daily life of the bodies possessing potential energy are given below
- The potential energy of water in dams is used to run turbines in order to produce electric energy from the generators.
- The potential energy of the wound spring of a clock is used to drive the hands of the clock.
- Due to the potential energy of the compressed spring in a loaded gun, the bullet is released with a large velocity on firing the gun.
- Due to the potential energy of the stretched bow, the arrow goes forward with a large velocity on releasing the bow.
Gravitational potential energyConsider that a body of mass M is lying at point A on the surface of earth. If g is acceleration due to gravity on the surface of earth, it will be attracted towards the centre of the earth with a force M g, equal to the weight of the body.
In order to move the body up from point A to B with zero acceleration, a force equal to M g has to be applied on the body in upward direction. If the body is moved through a height h, then work done
W = force distance = M g h
Therefore, potential energy = M g h
In fact, M g h will be equal to change in gravitational potential energy, which is usually called the change in potential energy of the body in going from point A to B. However, M g h will represent potential energy of the body at point B, if its potential energy at the surface of earth is taken as zero level of potential energy.