Question

A man stands in between two cliffs and fires a gun. He hears two successive echoes after 3 sec and 5 sec. What is the distance between two cliffs? (speed of sound = ${330ms}^{-1}$

Answer 1

For the first echo, If $S_1$ be the distance of the man from one cliff, the sound travels distance in 3 sec is $2S_1$.

For the second echo, if $S_2$ be the distance of the man from another cliff, the sound travels distance in 5 sec is $2S_2$

Using formula, $S=vt$,

$2S_1=330\left(3\right)$ or $S_1=495m$ and $2S_2=330\left(5\right)$ or $S_2=825m$

The distance between the cliffs $=S_1+S_2=495+825=1320m$