Question

A person standing between two vertical cliffs and $480m$ from the nearest cliff shouts. He hears the first echo after $3s$ and the second echo $2s$ later.
Calculate:
$\left(i\right)$ The speed of sound.
$\left(ii\right)$ The distance of the other cliff from the person.

Answer 1

$\left(i\right)$ Total distance travelled by the sound in going and coming back (in the case of the nearest cliff) $=2\times 480m$
Speed of sound $=\frac{Totaldistancetravelled}{Timetaken}=\frac{2\times 480}{3}$
$=320m/s$
$ii)$Time taken to reach second echo$=3+2=5s$
Now $v=\frac{2d}{t}$
$\Rightarrow$ $d=\frac{vt}{2}$
Distance of the other cliff from the person $=\frac{320\times 5}{2}=800m$