An ambulance is generating a siren sound at a frequency of 2,400 Hz. The speed of sound is 345.0 m/s. The observer is traveling at a velocity of 24.00 m/s toward the ambulance and the ambulance is traveling at a velocity of 24.00 m/s toward the observer. What is the frequency of the siren perceived by the observer?
A) 2,100 Hz
B) 2,250 Hz
C) 2,430 Hz
D) 2,550 Hz
E) 2,759 Hz

Question

Quizplus · Accepted Answer

The frequency perceived by the observer can be calculated using the formula for the Doppler effect: $ f' = f \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 towards the source, and $ v_s $ is the source's velocity towards the observer. Plugging in the given values: $ f' = 2400 \frac{345 + 24}{345 - 24} = 2400 \frac{369}{321} = 2759 $ Hz.

An Ambulance Is Generating a Siren Sound at a Frequency