# Moment of Inertia

The moment of inertia is sometimes called and referred to as "angular mass." It is the "amount of resistance" to rotational motion.

The moment of inertia of a **point mass** is

The moment of inertia is additive, therefore, for a rigid body consisting of point masses with distances to the rotation axis, the total moment of inertia is the sum of the point-mass moments of inertia

The moment of inertia is commonly used to calculate torque when multiplied by the angular acceleration. This analogous to F = ma.