Practice!

Sample Problem

What is the observed frequency of a siren with a frequency of 440 Hz moving away from you at 25 m/s? The speed of sound is 330 m/s.

Solution

We use the equation ff = f0 (v/ (v + v0)) , and we plug in our given values to get

ff = 440 (330/ (330 + 25) = 410 Hz