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 $340m{s}^{-1}$, the distance between the cliffs is?

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

Answer 1

Answer: (C)

$340$m

Let the distance between the two cliffs be d. Since, the man is standing midway between the two cliffs, then the distance of man from either end is $d/2$.
The distance travelled by sound (in producing an echo)
$2\times \frac{d}{2}=v\times t\Rightarrow d=340\times 1=340$m.