A driver approaches a stationary 440 Hz siren at 25 m/s.What is the frequency heard by the driver?

Question

Quizplus · Accepted Answer

The frequency heard by the driver increases due to the Doppler effect, which is calculated using the formula $f' = f \frac{v + v_d}{v}$, where $f'$ is the observed frequency, $f$ is the source frequency, $v$ is the speed of sound in air (approximately 343 m/s), and $v_d$ is the speed of the driver. Substituting the given values, $f' = 440 \frac{343 + 25}{343}$, which calculates to approximately 472 Hz.

A Driver Approaches a Stationary 440 Hz Siren at 25