Question

A source of sound and detector are placed at the same place on ground. At t = 0, the source S is projected towards reflector with velocity $V_0$ in vertically 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 $v(\gg v_0)$. Take f_0 as frequency of sound waves emitted by source. Based on above information answer the following questions.

Frequency of sound waves emitted by source at $t=\frac{v_0}{2g}$ is

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

Answer 1

The correct option is A $f_0$

Actual frequency emitted by source doesn’t depend upon the velocity of source but frequency heard may change due to relative motion between the observer and the source.