Question

A man standing 25 m away from a wall produces a sound and receives the reflected sound.

(a) Calculate the time after which he receives the reflected sound if the speed of sound in air is 350 m $s^{-1}$.

(b) Will the man be able to hear a distinct echo? Explain the answer.

Answer 1

Given the man is standing 25 m away from the wall hence the distance travelled by sound is 2 times the distance between man and wall.

ie total distance travelled =2 $\times$25m =50m

given speed of sound = 350m/s
(a) hence time taken by sound to reach observer ==0.14 seconds


(b) yes, the man will be able to hear the echo because the time taken by sound to reach the man is more than 0.1 seconds