# Moment of Inertia

## Definition - What does Moment of Inertia mean?

Moment of Inertia, also called rotational inertia or angular mass, is the rotational analog of a mass for the linear motion. The Moment of Inertia is used to analyze the torque required for angular acceleration about the rotational axis. Moment of Inertia is dependent on the axis and mass distribution of the body. To change the rotation of the body, more torque is required for larger moments. Moment of Inertia is used in the dynamics of rotational motion.

## Petropedia explains Moment of Inertia

Rotation axis defines the Moment of Inertia. *I*, i.e., the Moment of Inertia can be defined as the angular momentum's ratio *L, *around a principal axis, to the angular velocity. The angular velocity increases and the Moment of Inertia gets small if a system's angular momentum is constant. The Moment of Inertia for a simple pendulum depends on *m*, i.e., the mass of the pendulum and *r*, which is the distance from the pivot point. The formula for calculating Moment of Inertia for a simple pendulum is *I* = *mr*^{2}.