Question

an echo was heard after 3 s. what is the distance of the reflecting surface from the source, given that the speed of sound is 342 m/s?

Answer 1

Speed of the sound = 342 m/s
Echo returns in time = 3 s

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

= 1026m
As it has to travel twice the distance from the reflecting surface from the source.
Therefore, the distance travelled will be, 1026/2 = 513 m

Answer 2

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Speed of sound, v = 342 m s−1

Echo returns in time, t = 3 s

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

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 = (1026/2)m= 513m

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