Question

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

Answer 1

Answer: (C)

332 m/sec

Answer 2

$n' = n\left( \frac{v + v_{O}}{v} \right) \Rightarrow 2n = n\left( \frac{v + v_{0}}{v} \right) \Rightarrow \frac{v + v_{0}}{v} = 2$

$\Rightarrow$ $v_{O} = v = 332$m/se