Question

The difference between the apparent frequency of a source of sound as perceived by the observer during its approach and recession is $2\%$ of the frequency of the source. If the speed of the sound in air is $300ms$, the velocity of the source is :

• A. $1.5ms$
• B. $12ms$
• C. $6ms$
• D. $3ms$

Answer 1

The correct option is D $3ms$

Frequency during approach-Frequency during recession=$\frac{2}{100}\times f_0$

$⟹f_0\left(\frac{c+v}{c}\right)-f_0\left(\frac{c-v}{c}\right)=\frac{2}{100}{f}_0$

$⟹\frac{2v}{300}=\frac{2}{100}$

$⟹v=3m/s$