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A child hears an echo from a cliff 4 sec...

A child hears an echo from a cliff 4 seconds after the sound from a powerful cracker is produced. How far away is the cliff from the child? Velocity of sound in air at 20°C is `344 m s^(-1)`.

Text Solution

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Let the distance between the child and the cliff be d. Then,
Total distance travelled by the sound = 2d
Total time taken by the sound = 4 s
Then, velocity of sound `= (2d)/( 4s) = (d)/( 2s)`
`344"m s"^(-1) = (d)/( 2s)`
This gives, `d = 344" m s"^(-1) xx 2" s" = 688` m
Thus, the cliff is at a distance of 688 m from the child.
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