Q. A man stands in front of a hillock and fires a gun. He hears an echo after $1.5\ sec.$ The distance of the hillock from the man is (velocity of sound in air is $330\ m/s$)
A) $220\ m$
B) $247.5\ m$
C) $268.5\ m$
D) $292.5\ m$
Explanation
(b) If $d$ is the distance between man and reflecting surface of sound then for hearing echo
$2d = v \times t \Rightarrow d = \frac{330 \times 1.5}{2} = 247.5\ m$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.