Wave Motion> A source of sound of frequency 256 Hz is ...

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

Simran Bhatia , 10 Years ago

Grade 11

2 Answers

Aditi Chauhan

Last Activity: 10 Years ago

Hello Student,

Please find the answer to your question

NOTE : If the sound reaches the observer after being reflected from a stationary surface and the medium is also stationary, the image of the source in the reflecting surface will become the source of the reflected sound.

v = v [c – v₀/c – v_s]

v₀, v_s are +ve if they are directed from source to the observer and – ve if they directed from observer to source.

v = 256 [330 – (- 5)/330 – 5] = 264 Hz

∴ Beat frequency = 264 – 256 = 8

Thanks

Aditi Chauhan
askIITians Faculty

Rishi Sharma

Last Activity: 4 Years ago

Dear Student,
Please find below the solution to your problem.

If the sound reaches the observer after being reflected from a stationary surface and the medium is also stationary,
the image of the source in the reflecting surface will become the source of the reflected sound.
v=v[c–v−o/c–vs]
vo, vs are +ve if they are directed from source to the observer and –ve if they directed from observer to source.
v=256[330–(−5)/330–5]=264Hz
∴ Beat frequency =264–256=8

Thanks and Regards