A pendulum is made by suspending a solid circular disk from a pivot point that is at the edge of the disk with the plane of the disk lying in the vertical plane. The period of oscillation of the disk is T. If a disk with the same radius but a mass four times is great is suspended the same way, what will be its period of oscillation?
A)4T
B)T/2
C)2T
D)T
E)T/4

Question

Quizplus · Accepted Answer

The period of a physical pendulum depends on the moment of inertia and the distance from the pivot to the center of mass. Since the radius is the same and the mass is four times greater, the moment of inertia increases by a factor of four, but the period is independent of mass for a pendulum of this type. Therefore, the period remains T.

A Pendulum Is Made by Suspending a Solid Circular Disk