A person standing on a road sends a sound signal to the driver of a car going away from him at a speed of `72 km h^-1. The signal travelling at `330 m s^-1 in air and having a frequency of 1600 Hz gets reflected from the body of the car and returns. Find the frequency of the reflected signal as heard by the person.

Answer

A, D

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+20)xx1600=1417Hz`