Question

A man is standing between two cliffs. If he claps his hands once, a series of echoes at the intervals of one second are heard. If the speed of sound is $340m{s}^{-1}$ the distance between the cliffs is

• A. $170m$
• B. $680m$
• C. $340m$
• D. $510m$

Answer 1

The correct option is C $340m$

Given: velocity of sound $v=340m/s$

Time intervals to hear echo $t=1sec$

Let the distance between the two cliffs be $x$ metre and between the man and the cliff 1 be $y$ metres.

The man hears echo coming from both cliff 1 and cliff 2.

Now $d=vt$

For cliff 1: $2y=340\times 1⟹2y=340$

For cliff 2: $2(x-y)=340\times 1⟹2x-2y=340$

Thus $2x-340=340⟹x=340m$