Question

The frequency changes by 10% as a sound source approaches a stationary observer with constant speed V_S. What would be the percentage change in frequency as the source recedes the observer with the same speed .Given that V_s < V_a (V_a = speed of sound in air) 

(a) 14.3% 

(b)20% 

(c) 10.0% 

(d)8.5% 

Answer 1

The correct option (d)8.5%

Explanation:

Case I : (Source approaches a stationary observer)

Case II : (Source recedes the stationary observer)

Here, − sign indicates a decrease in frequency.