Question

A man, standing between two cliffs, claps his hands and starts hearing a series of echoes at intervals of one second. If the speed of sound in air is 340 $m{s}^{-1}$, The distance between the cliffs is

• A. 1700 m
• B. 680 m
• C. 1620 m
• D. 340 m

Answer 1

The correct option is D

340 m

Let the person be a distance of ‘x’m from cliff 1 and at a distance of ‘y’m from cliff 2.

The sound travels a distance of 2x in 1 second and produces one

Distance = velocity $\times$ time

$2x=340\times 1\Rightarrow x=170m$

The sound travels a distance ‘2y’ in 1 second,

$\Rightarrow$ y = 170m

$\therefore$ Distance between the cliffs = 170 + 170 = 340m