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

Question

Quizplus · Accepted Answer

The frequency perceived by the observer can be calculated using the Doppler effect formula for sound: $f' = f \frac{v + v_o}{v - v_s}$, 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. Substituting the given values: $f' = 2400 \frac{345 + 24}{345 - 24} = 2759 \mathrm{~Hz}$.

An Ambulance Is Generating a Siren Sound at a Frequency 345.0 m/s345.0 \mathrm{~m} / \mathrm{s}345.0 m/s

An Ambulance Is Generating a Siren Sound at a Frequency $345.0 \mathrm{~m} / \mathrm{s}$