PHYSICS [3 Mark Question Answer]

Energy is the ability of a body to do work. So, there is a direct relationship between energy and work. For example, when an object is at a height from the ground, it has a certain amount of potential energy. When we drop the object, it falls because of the force of gravity. White falling down, its kinetic energy is gradually used up until it becomes zero (just when the object touches the ground). At any point during its fall, the amount of kinetic energy which is used up by the body is equal to the distance it has travelled (work done). So, amount of work done by a body = amount of energy change in the body.

The energy possessed by a body due to the work done on it is called as mechanical energy. Work is done on a body when the body is displaced. So, the energy gained by a body due to its state of motion (during displacement) or due to its position (at the end of displacement) is known as mechanical energy. Mechanical energy is of two types –

• Kinetic energy – Energy possessed by a body due its motion or movement. Example : Flowing water, wind possess kinetic energy.
• Potential energy – Energy possessed by a body due to its position.

It is of two types –(a) Gravitational potential energy – Energy possessed by a body due to its raised position (height). Work is done to raise a body to a certain height against the pull of gravity.
Example : Mango on a tree, flower pot placed on a balcony possess gravitational potential energy.

(b) Elastic potential energy – Energy that gets stored in a body when the body is stretched, compressed or bent
Example : A stretched bow, a winded spring of toy and coiled spring used in watches possess stored elastic potential energy.