The apparent frequency of the whistle of an engine changes in the ratio 6:5 as the engine passes a stationary observer. If the velocity of sound is `330(m)/(s)`, then the velocity of the engine is

Options

A. `3(m)/(s)`
B. `30(m)/(s)`
C. `0.33(m)/(s)`
D. `660(m)/(s)`

Answer

B

Explanation

`v'=(v)/(v-v_S)v`,`v''=(v)/(v+v_S)v`
`(v')/(v'')=(v+v_S)/(v-v_S)` or `(6)/(5)=(330+v)/(330-v)`
`11v_S=330` or `v_S=30(m)/(s)`