Question

An echo is heard in 3 s. What is the distance of the reflecting surface from the source, given that the speed of sound is 342 ms-1?​

Answer 1

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Speed of sound (v) = 342 ms-1

Echo returns in time (t) = 3 s

Distance travelled by sound = v × t = 342 × 3 = 1026 m

In the given interval of time, sound must travel a distance which is twice the distance of reflecting surface and source.

Therefore, the distance of reflecting surface from the source =1026/2 = 513 m.

Answer 2

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In the given time interval, sound has to travel a distance that is twice the distance of the reflecting surface and the source. Hence, the distance of the reflecting surface from the source = 1026/2m = 513 m.