Question

A man standing 825 meters away from a cliff (steef rock) Fires a gun. After how long will he hear it's echo ? Speed of sound in air is 330 m/s.

Answer 1

Distance of the man from the cliff(d)=825m
Speed of sound(v)=330 m/s
By the echo formula,
2d=vt
t=2d/v=2×825/330=1650/330=5s(Ans.)
Hence,the man would hear the echo after 5s

Answer 2

Answer:

5 seconds

Explanation:

For the echo to reach the man it has to travel to the cliff and back.

This means if distance from the cliff to the man is d then the distance traveled by the echo is 2d.

The distance traveled by the echo =

= 825 × 2 = 1650 meters

Given distance and speed we can get time.

Time = Distance / Speed

Speed = 330 m/s

Time = 1650/330 = 5 seconds.