A siren emitting a sound of frequency 800 Hz moves away from an observer towards a cliff at a speed of15 ms^-1. Then, the frequency of sound that the observer hears in the echo reflected from the cli…

Question

A siren emitting a sound of frequency 800 Hz moves away from an observer towards a cliff at a speed of15 ms^-1. Then, the frequency of sound that the observer hears in the echo reflected from the cliff is (Take velocity of sound in air =330ms^-1)

Accepted Answer

Correct answer: A. (a) Here, frequency of sound emitted by siren, _0=800 Hz Speed of source, v_s=15ms^-1 Speed of sound in air, v=330ms^-1 Apparent frequency of sound at the cliff =frequency heard by observer =u Using Doppler’s effect of sound = ( vv-v_s ) _0= 330330-15 800 = 330315 800=838.09 Hz =838 Hz

$A siren emitting a sound of frequency 800 Hz moves away from an observer towards a cliff at a speed of15 m s^{- 1} . Then, the frequency of sound that the observer hears in the echo reflected from the cliff is (Take velocity of sound in air = 330 m s^{- 1})$

Solution

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