Question

An observer standing on a railway crossing receives frequency of 2.2 kHz and 1.8 kHz when the train approaches and recedes from the observer. Find the velocity of the train.

(The speed of the sound in air is 300 m/s)

Answer 1

From the relation, f' = f(v/v ±v_s),

Here, v_T = v_s = velocity of source/train

Solving Eqs. (i) and (ii), we get

v_T = 30 m/s