Question

An ambulance driving 50.0 m/s emits a sound wave with a wavelength of 80.0 centimeters. As it drives toward a hospital, which of the following is the only possible frequency heard by the medical staff who are standing at the entrance? Speed of sound is 343 m/s.

Answer 1

Answer:

502 Hz

Explanation:

Initial frequency, F is given by F=v/w where f is frequency, v is speed of sound in air and w is wavelength. Therefore, substituting 80cm whicj is 0.8 m for w and 343 m/s for v then

F=343/0.8=428.75 Hz

The frequency at entrance, f will be given by

$f=\frac {v\times F}{v-v_a}$ where va is speed of ambulance, v is speed of sound in air, F is initial frequency. Substituting 343 m/s for v, 428.75 Hz for original frequency and 50 m/s for speed of ambulance then

$f=\frac {343\times 428.75}{343-50}=501.91552901023\approx 502 Hz$