Question

A person standing between a pair of tall and wide cliffs claps his hands. He hears the first two echoes at 2 sec and 3 sec respectively. If the speed of sound is 330 m/sec, then

• A. Separation between the cliffs is 825m
• B. The time of third echo is 5 second
• C. every third echo is the loudest
• D. after the second echo,none is formed

Answer 1

The correct option is A Separation between the cliffs is 825m

Given that,

Speed of sound $v=330m/s$

Time

$t_1=2s$

$t_2=3s$

Let $d_1$= distance to near wall and $d_2$ distance to far wall

Now, the distance to the near wall and back is

$2d_1=Speed\times time=330\times 2$

$2d_1=660m$

Now, the distance is half

$d_1=330m$

Now, the distance to the far wall and back is

$2d_2=330\times 3$

$2d_2=990m$

The distance is half

$d_2=495m$

Now, the total distance is

$d=d_1+d_2$

$d=330+495$

$d=825m$

Hence, the Separation between the cliffs is $825m$