Question

In the figure shown a source of sound of frequency 510 Hz moves with constant velocity $v_s=20m/s$ in the direction shown. The wind is blowing at a constant velocity $v_{\omega }=20m/s$ towards an observer who is at rest at point B. The frequency detected by the observer corresponding to the sound emitted by the source at initial position A, will be (speed of sound relative to air = 330 m/s)

• A. 485 Hz
• B. 500 Hz
• C. 512 Hz
• D. 525 Hz

Answer 1

The correct option is D 525 Hz

$f^{\prime }=f\frac{(u+v_{\omega })}{(u+v_{\omega }-v_{s}cos{60}^{\circ })}=\frac{510(330+20)}{330+20-20cos{60}^{\circ }}=525Hz$