Q. A man standing on a cliff claps his hand hears its echo after $1\ sec.$ If sound is reflected from another mountain and velocity of sound in air is $340\ m/sec.$ Then the distance between the man and reflection point is
A) $680\ m$
B) $340\ m$
C) $85\ m$
D) $170\ m$
Explanation
(d) If $d$ is the distance between man and reflecting surface of sound then for hearing echo
$2d = v \times t \Rightarrow d = \frac{340 \times 1}{2} = 170\ m$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.