Question

A person claps his hands in an empty hall. He heard the echo of the sound after 0.5 seconds. What distance between the source of the sound and the reflecting surface. Given the speed of sound in air is 343 m/s?

• A. 857.5 m
• B. 85.75 m
• C. 0.08575 km
• D. 0.8575 km

Answer 1

Answer: (B), (C)

The correct options are
B 85.75 m
C 0.08575 km

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

Time taken for the echo to reach the source:
$t=\frac{s}{v}$
$0.5=\frac{2d}{343}$
$d=85.75m=0.08575m$