Question

A source of the sound of frequency $f_1$ is placed on the ground. A detector placed at a height is released from rest on this source. The observed frequency f(Hz) is plotted against time t(sec). The speed of sound in air is 300 m/s. Find $f_1(g=10m/s^2)$.

• A.
• B.
• C.
• D.

Answer 1

The correct option is B

$f=\left(\frac{V+V_0}{V}\right)f_1=f_1+f_1\frac{V_0}{V}{V}_0=gtSo,f=f_1+\left(\frac{f_{1}g}{V}\right)tSlopeofgraph=\frac{f_{1}g}{V}\frac{\left(2\right)\left({10}^{-3}\right)-f_1}{30}=\frac{\left(f_1\right)\left(10\right)}{300}or{f}_1={10}^{3}Hz$