A simple pendulum that consists of a small ball of mass m and a massless wire of length L swings with a period T.Suppose now that the mass is rearranged so that mass of the ball was reduced but the mass of the wire was increased,with the total mass remaining m and the length being L.What is true about the new period of swing? (There could be more than one correct choice. )
A)The new period is T because the total mass m has not changed.
B)The new period is T because the length L has not changed.
C)The new period is greater than T.
D)The new period is less than T
E)The new period is T because neither L nor m have changed.

Question

Quizplus · Accepted Answer

The period T of a simple pendulum is given by T=2π√(L/g), where g is the acceleration due to gravity. As the mass of the ball is reduced and the mass of the wire is increased, the moment of inertia of the pendulum increases (since the mass is farther from the axis of rotation), making it take longer to swing back and forth. Therefore, the new period of swing is longer than T, and the correct choice is D.

A Simple Pendulum That Consists of a Small Ball of Mass