When the listener moves towards a stationary source with a velocity `v_(1)` m the apparent freqency of a note emitted by the source is f' When the listener moves away from the source with the same velocity, the apparent frequency of the note f/f'=3. If v the velocity of sound in air, the value of `v//v_(1)` is -

Options

A. 3
B. `1//2`
C. 2
D. 1

Answer

3

Explanation

When listener moves
`f=f((v+v_(t))/(v))`
When moves away
`f=f((v-v_(t))/(v))`
`(f')/(f'')=3`
`rArr(v+v_(t))/(v-v_(t))=3`
`rArrv+v=3v-3v_(t)`
`rArr4v_(t)=2v`
`rArrv=v_(t)`
`(v)/(v_(t))=2`