A car horn emits a frequency of 400 Hz. A car traveling at 20.0 m/s sounds the horn as it goes away from a stationary pedestrian. What frequency does the pedestrian hear? The speed of sound in air is 343 m/s.

Question

Quizplus · Accepted Answer

The frequency heard by the pedestrian is calculated using the Doppler effect formula for a source moving away: f' = f * (v / (v + vs)), where f = 400 Hz, v = 343 m/s, and vs = 20 m/s. This gives f' = 400 * (343 / (343 + 20)) = 378 Hz.

A Car Horn Emits a Frequency of 400 Hz