: The mass or inertia is the property of bodies by virture of which the bodies has a tendency to

remain at rest or in state of uniform linear motion unless an external force is exerted on them. Greater is the mass of the body, greater is the external force required to brings it in position of rest or uniform motion. Similarly, in order to rotate a body about an axis, a torque has to be applied on the body. This is described by saying that the body has a moment of inertia about the axis of rotation. The greater is the moment of inertia of a body about an axis, the greater is the torque required to rotate or to stop the body about that axis. Thus, the moment of inertia plays the same role in the rotational motion as mass or inertia plays in translational motion.