Submarine `A` is going with speed of `18km//hr`. Submarine `B` is chasing `A` with speed of `27 km//hr`. It sends frequency of `500Hz` and hears after reflection from `A`. The perceived frequency is :
`(V_("sound in water")=1500m//s)`

Options

A. 502Hz
B. 499Hz
C. 504Hz
D. 507Hz

Answer

A

Explanation

Case - I
( B ) Source ( A ) Observer
`v^(1) =v[(1500 - 5 )/(1500 - 7.5)]`
Case -II ( B ) Observer ( A ) Source
`v^(11) = v^(1)[(1500 + 7.5)/(1500 + 5)] ~~502 Hz`