Question

You are moving at 120 km/h toward a stationary train. The train blows its 400-Hz whistle. Take the speed of sound to be 340 m/s. What frequency do you hear?

Answer 1

F = ((V+Vr) / (V+Vs)) * Fo.

V = 120000m/h * (1/3600)h/s = 33.33m/s.

F=((340+33.33) / (340+0))*400=439.2Hz.

Answer 2

6.9 m/s