Given
Speed of sound (u) = 342 m/s
Time taken for hearing the echo (t) = 6 s
Now
speed= \(\frac{distance}{time}\)
⇒ 342 =\(\frac{distance}{6}\)
⇒ Distance travelled by the sound = 342 ×6 = 2052 m.
In 6s, sound has to travel twice the distance between the source and reflecting surface. Therefore, the distance of the reflecting surface from the source =\(\frac{2052}{2}\) = 1026 m
Distance of reflecting surface = 1026 m.