A source of sound of frequency 256 Hz is moving rapidly towards wall with a velocity of $5 \mathrm{~

Question

A source of sound of frequency 256 Hz is moving rapidly towards wall with a velocity of $5 \mathrm{~m} / \mathrm{sec}$. How many beats per second will be heard if sound travels at a speed of $330 \mathrm{~m} / \mathrm{sec}$ ?\

Professor PC Thomas Classes · Answer

If the reflector of sound is stationary, the image of the source in the reflecting surface will act as the source of reflected sound.\ $	herefore \quad f^{\prime}=f \frac{\left(v+v_{o}ight)}{\left(v-v_{S}ight)}$. The observer travels with the sound-source e.g. in a whistling engine/train or in a horning bus.\ or $f^{\prime}=256 \frac{(330+5)}{(330-5)}$\ or $f^{\prime}=\frac{256 	imes 335}{325}=264$\ $	herefore$ Beat frequency $=f^{\prime}-f=264-256=8 \mathrm{~Hz}$.\