The apaarent frequency of a note is 200 Hz when a listener is with a velocity of `40 ms^(-1)` towards a stationary source. When he moves away from the same source with the same speed, the apparent frequency of the same note is 160 Hz. The velocity of sound in air in m/s is :

Options

A. 330
B. 320
C. 340
D. 360

Answer

D

Explanation

When the listener moves towards the source,
`v'=(v+v_(0))/(v)xxv`
`=200=(v+40)xxv " "....(1)`
When the listener moves away form the source,
`160=(V-40)/(v)xxv " "...(2)`
From (1) and (2)
`(200)/(160)=(v+40)/(v-40)`
(or) `v=360 ms^(-1)`