A 1024 Hz tuning fork is dangled at the end of a string such that its center of mass is 1.2 m below the point at which the other end of the string is attached to door frame, making a pendulum of sorts. The tuning fork may be treated as a point mass for the purposes of this problem. The pendulum is brought to a maximum angle and released. If the range of frequencies heard by an observer standing in the plane of the pendulum's motion is 1020-1028 Hz, what is the angle to which the pendulum was raised? The speed of sound is 340 m/s.
A) 22°
B) 18°
C) 17°
D) 46°
E) 4.3°

Question

Quizplus · Accepted Answer

The correct answer is A because the range of frequencies heard by an observer standing in the plane of the pendulum's motion is 1020-1028 Hz, which corresponds to a maximum angle of 22°.

A 1024 Hz Tuning Fork Is Dangled at the End