Question

An engine is moving on a circular path of radius $100\, m$ with a speed of $20 \,m / s$. What will be the frequency observed by an observer standing stationary at the centre of rircular path when the engine blows a whistle of frequency $500 \,Hz$ ?

• A. More than 500 Hz
• B. Less than 500 Hz
• C. 500 Hz
• D. No sound is heard

Answer 1

Answer: (C)

500 Hz

Answer 2

As motion of the source is always perpendicular to the direction of propagation of sound, so there will be Doppler's effect.