# A siren emitting a sound of frequency 800 Hz moves away from an observer towards a cliff at a speed of 15ms^-1. Then the frequency of sound that the

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A siren emitting a sound of frequency 800 Hz moves away from an observer towards a cliff at a speed of 15ms^-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)
A. 800Hz
B. 838Hz
C. 885 Hz
D. 765Hz

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