Question

Two train whistles have identical frequencies of 220 Hz. When one train is at rest in the station sounding its whistle, a beat frequency of 10.0 Hz is heard from the other train that is approaching the station. What is the speed of the approaching train? Assume that the speed of sound is 340 m/s.

Answer 1

Speed of the approaching train = 15.45 m/s

Step-by-step explanation:

Given:

Frequency F0 = 220 Hz

Beat frequency F1 = 10.0 Hz

Find:

Speed of the approaching train

Computation:

Approaching frequency F2 = 220 + 10.0 Hz

Approaching frequency F2 = 230 Hz

Doppler shift;

F = [(v+v0)/(v-vS)]F0

230 = [(340+v0)/(340-0)]220

V0 = 15.45 m/s

Speed of the approaching train = 15.45 m/s