posted by utl on .
A stationary horn emits a 151 Hz tone. What frequency is heard by a passenger on a train which is moving towards this horn with a speed of 28.7 m/s?
Fh = 151 Hz
Vr = 28.7 m/s
Vs = 343 m/s
Fr = ((Vs+Vr)/(Vs-Vh)) * Fh
Fr = ((343+28.7)/(343-0)) * 151 Hz =
(371.7/343) * 151 = 163.6 Hz = Freq.
heard by the receiver(Passenger).