A source emits sound at a fixed constant frequency f . If the source moves away from you, and at the same time you run away from the source, the frequency you hear is
A) the same as f.
B) higher than f.
C) lower than f.
D) unrelated to f.

Question

Quizplus · Accepted Answer

When the source moves away from the observer, the frequency of the sound waves emitted by the source is lengthened, which leads to a lower frequency (as the speed of sound remains constant). And when the observer runs away from the source, the observed frequency is further reduced. Therefore, the frequency heard by the observer is lower than the frequency emitted by the source, making choice C the correct answer.

A Source Emits Sound at a Fixed Constant Frequency F