an ambulance emits a siren with a frequency of 300 Hz if the

an ambulance emits a siren with a frequency of 300 Hz. if the ambulance is moving away from the observer at 80 m/s, what is the frequency the observers will hear?

Solution

Using doppler\'s effect:

when source is moving away from observer at rest, then

f1 = f0*(v/(v + vs))

v = speed of sound = 343 m/sec

vs = speed of source = 80 m/sec

f0 = 300 Hz

f1 = 300*(343/(343 + 80)) = 243.26 Hz