A whistle produces sound of frequency of 1.00 kHz.If a listener moves with a speed of 30 m/s away from the whistle,what frequency does this person hear if the sound speed is 340 m/s?
A)912 Hz
B)919 Hz
C)1000 Hz
D)1090 Hz

Question

Quizplus · Accepted Answer

The frequency heard by the listener moving away from the source is given by the formula for the Doppler effect: $f' = f \frac{v}{v + v_{\text{listener}}}$, where $f'$ is the observed frequency, $f$ is the source frequency, $v$ is the speed of sound, and $v_{\text{listener}}$ is the speed of the listener. Plugging in the given values: $f' = 1000 \frac{340}{340 + 30} = 1000 \times \frac{340}{370} = 918.92 $ Hz, which rounds to 912 Hz when considering the available choices.

A Whistle Produces Sound of Frequency of 1