Question

A person clapped his hands in an empty room. He heard the echo of the clap after 5 seconds. What is the distance between the source of the sound and the reflecting surface? It is given that the speed of sound in air is 343 m/s?

• A. 912 m
• B. 85.75 m
• C. 857.5 m
• D. 0.8575 km

Answer 1

Answer: (C), (D)

0.8575 km

Let, the distance between the source of sound and the reflecting surface be d.
Total distance that sound travels = 2d
Speed of the sound wave = 343 m/s

Time taken for the echo to reach the source = $\frac{2d}{343}=5$
d = 857.5 m.