Inertia is the inherent property of a body to oppose the change of natural state. It can be expressed as the tendency of the body to oppose any change in its state of rest or uniform motion. Measure of inertia is mass with SI unit as kg.

An object will continue to be in the state of rest or in a state of motion unless an external force acts on it is called Inertia 

It can be expressed as the tendency of the body to oppose any change in its state of rest or uniform motion. Measure of inertia is mass with SI unit as kg.