1. Tardigrade
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  4. A siren emitting a sound of frequency 800 Hz moves away from an observer towards a cliff at a speed of 15 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 = 330 ms -1 )

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Q. A siren emitting a sound of frequency $800\, Hz$ moves away from an observer towards a cliff at a speed of $15\, ms ^{-1}$. Then, the frequency of sound that the observer hears in the echo reflected from the cliff is : (Take velocity of sound in air = $330\, ms ^{-1}$ )

Solution:

$n'=\frac{ nv }{ v - v _{ s }}$
$=800 \times \frac{330}{315}$
$=838\, Hz$
image
$\therefore $ Observer hears
$n'=838\, Hz$