Moment of Inertia
The equation used to calculate the moment of inertia of a collection of discrete masses about an arbitrary axis of rotation is
where m is the mass of each piece and r is its moment arm, or perpendicular distance, from the line of action of the axis of rotation. Recall that the moment of inertia is a quantity that determines the collection's rotational inertia, or resistance to a change in its state of rotation.
