Question

Why is it called a moment of inertia?

Answer 1

Moment of Inertia (I):

1. The moment of inertia of a body is also known as rotational inertia of a rigid body which is the measure of the amount of torque required to rotate the rigid body around an axis.
2. It depends on the distribution of mass of the body.
3. Bodies with a larger moment of inertia require high torque to rotate.
4. For a point mass moment of inertia is just, $massxsquareofperpendiculardis\tan cefromrotationaxis$.

Why is it called moment of inertia?

1. It can be questioned that why is called moment of inertia and not moment of force, when it is the measure of amount of torque, which is force applied. This can be clarified by the definitions of moment of force and inertia.
2. Moment of a force: The moment of a force is the measure of a force to rotate a body around an axis or a point.
3. Inertia: Inertia is the resistance of an object to a change in its motion.
4. Moment of inertia resists rotational motion and hence called moment of inertia and not moment of force.