Question

A person claps his hands in an empty room. He heard the echo of the sound after 5 seconds. What is the distance between the source of the sound and the reflecting surface? (Speed of sound in air is 343 m/s)

• A. 1
• B. 3500 m
• C. 857.5 m
• D. 999 m

Answer 1

The correct option is C 857.5 m

Let, the distance between the source of sound and the reflecting surface be 'd' metres.
Total distance that sound travels = 2d metres
Speed of the sound wave = 343 m/s
Time taken for the echo to reach the source = $\frac{2d}{343}$ = 5 seconds (Given).
Thus, d = 857.5 m.