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, if the speed of sound in air is given as $340m{s}^{-1}$?

• A. 912 m
• B. 3500 m
• C. 850 m
• D. 999 m

Answer 1

The correct option is C 850 m

Let, the distance between the source of sound and the reflecting surface be $d$
Hence, total distance the sound travels is: $d^{\prime }=2d$

Given,
Time taken for the echo to reach the source, $t=5s$
Speed of the sound wave, $v=340m{s}^{-1}$

From formula of speed,
$v=\frac{2d}{t}$
$5=\frac{2d}{340}$
$⟹d=850m$