Question

A source of sound and a detector are placed at the same place on ground. At $t=0$ , the source $S$ is projected towards reflector with velocity $v_0$ in vertical upward direction and reflector starts moving down with constant velocity $v_0$. At $t=0$ , the vertical separation between the reflector and source is $H(>\frac{v_0^2}{2g})$. The speed of sound in air is $v(>>v_0)$. Take $f_0$ as the frequency of sound waves emitted by source. Find frequency of sound waves emitted by source at $t=\frac{v_0}{2g}$.

• A. $f_0$
• B. $f_0\left(\frac{v}{v+\frac{v_0}{2}}\right)$
• C. $f_0\left(\frac{v-\frac{v_0}{2}}{v+\frac{v_0}{2}}\right)$
• D. $f_0\left(\frac{v-\frac{v_0}{2}}{v}\right)$

Answer 1

The correct option is A $f_0$

Actual frequency of sound is not affected by the relative motion of source and observer.

Hence, option (a) is the correct answer.