Question

A torsional pendulum executes simple harmonic motion by rotating about its axis. It consists of a coil spring attached to a balance wheel (a disk in this case). Recall that a torsional pendulum is similar to a normal pendulum with force replaced by torque, linear displacement replaced by angle turned, and mass replaced by moment of inertia. The spring constant is replaced by torsion constant. Assume the balance wheel of such a torsional pendulum is doubled in size but the torsion constant of the spring remains the same. The density of the disk remains the same, but both the radius and the thickness double. What happens to the period of the pendulum?

a. The period goes up by a factor of 4?2

b. The period doubles

c. The period goes up by a factor of 4

d. The period goes up by a factor of ?2

e. None of the other answers

Answer 1