A stationary siren blares at 200 Hz. A person traveling in a car at 40 m/s toward the siren hears the siren at a frequency of (use 344 m/s for the speed of sound)

Question

Quizplus · Accepted Answer

The observed frequency can be calculated using the formula for the Doppler effect when the source is stationary and the observer is moving towards the source: $f' = f \left(\frac{v + v_o}{v}\right)$, where $f'$ is the observed frequency, $f$ is the source frequency, $v$ is the speed of sound, and $v_o$ is the observer's speed towards the source. Plugging in the given values: $f' = 200 \left(\frac{344 + 40}{344}\right) = 200 \left(\frac{384}{344}\right) \approx 223 Hz$.

A Stationary Siren Blares at 200 Hz