A pendulum is a mass that is attached to a pivot, from which it can swing freely. Pendulum consisting of an actual object allowed to rotate freely around a horizontal axis.
Any swinging rigid body free to rotate about a fixed horizontal axis is called a compound pendulum or physical pendulum. The appropriate equivalent length L for calculating the period of any such pendulum is the distance from the pivot to the center of oscillation. The period of a compound (physical) pendulum is depended on the mass of the rigid body , its Moment of inertia and the distance between the pivot point and the center of mass.
|I||Moment of inertia (kg*m2)|
|D||Distance between the pivot point and the center of mass (m)|