Q. An observer moves towards a stationary source of sound of frequency $n.$ The apparent frequency heard by him is $2n.$ If the velocity of sound in air is $332\ m/sec,$ then the velocity of the observer is
A) $166\ m/sec$
B) $664\ m/sec$
C) $332\ m/sec$
D) $1328\ m/sec$
Explanation
(c) $n^{'} = n\left( \frac{v + v_{o}}{v} \right) \Rightarrow 2n = n\left( \frac{v + v_{o}}{v} \right) \Rightarrow \frac{v + v_{o}}{v} = 2$
$\Rightarrow v_{o} = v = 332\ m/sec$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.