Question

A siren emitting sound of frequency \(800\text{ Hz}\) is going away from a static listener with a speed of \(30\text{ m/s}\). Frequency of sound heard by the listener is \((\text{Velocity of sound in air}=340\text{ m/s})\)

• A. \(286.5\text{ Hz}\)
• B. \(418.2\text{ Hz}\)
• C. \(733.3\text{ Hz}\)
• D. \(644.5\text{ Hz}\)

Hint:

When the source moves away from the observer, apparent frequency decreases. Use \(f'=f\frac{v}{v+v_s}\).

Answer 1

The Correct Option is C