Question

A siren placed at a railway platform is emitting sound of frequency 5 kHz. A passenger sitting in a moving train A records a frequency of 5.5kHz, while the train approaches the siren. During his return journey in a different train B, he records a frequency of 6.0 kHz while approaching the same siren. The ratio of the train B to that of train A is

(A) 242/252

(B) 2

(C) 5/6

(D) 11/6

Answer 1

Correct option (B) 2

Explanation :

VB = speed of train B

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

vB/vA = 2