A boy riding on a bicycle going at `12 km h^-1` towards a vertical wall whistles at his dog on the ground. If the frequency of the whistle is `1600 Hz` and the speed of sound in air is `330 m s^-1`, find (a) the frequency of the whistle as received by the wall (b) the frequency of the reflected whistle as received by the boy.

Answer

A, B, C

Explanation

a. Required frequency
`n=(v+v_0)/(v-v_s)xxn_0`
`=(330+0)/(330-(10/3))xx1600=1616Hz`
b. Required frequency
`n=(v+v_0)/(v+v_s)xxn_0`
`=(330+(10/3))/330+0)xx1616=1632Hz`