An ambulance is generating a siren sound at a frequency of 2,400 Hz. The speed of sound is 345.0 m/s. If the ambulance is traveling at a velocity of 24.00 m/s toward the stationary observer, then what is the frequency of the siren perceived by the observer?
A) 2,579 Hz
B) 2,540 Hz
C) 2,525 Hz
D) 2,500 Hz
E) 2,480 Hz

Question

Quizplus · Accepted Answer

The frequency perceived by the observer can be calculated using the formula for the Doppler effect: $f' = f \times \frac{v + v_o}{v - v_s}$, where $f'$ is the perceived frequency, $f$ is the source frequency, $v$ is the speed of sound, $v_o$ is the observer's velocity (0 m/s since the observer is stationary), and $v_s$ is the source's velocity towards the observer. Plugging in the given values: $f' = 2400 \times \frac{345.0 + 0}{345.0 - 24.00} = 2400 \times \frac{345.0}{321.0} \approx 2579$ Hz.

An Ambulance Is Generating a Siren Sound at a Frequency