A whistle producing sound waves of frequencies `9500 Hz` and above is approaching a stationary person with speed `vms^(-1)`. The velocity of sound in air is `300 ms^(-1)`. If the person can hear frequencies upto a maximum of `10,000 Hz`.The maximum value of `v` upto which he can hear whistle is

Options

A. `30 ms^(-1)`
B. `15sqrt(2) ms^(-1)`
C. `15sqrt(2)ms^(-1)`
D. `15 ms^(-1)`

Answer

D

Explanation

`f' = f"(C)/(C - V)`
`10000 = 9500 xx (300)/(300 - V)`

`300 - V = 3 xx 95`
`V = 15 m//s`