Question

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

1. Calculate the time after which he receives the reflected sound if the speed of the sound in air is 350 m/s^-1.
2. Will the man be able to hear a distinct echo? Explain the answer.

Answer 1

1. d = 25 m;
   t = ?
   
   v = `(2d)/t`
   t = `(2d)/v`
   = `(2 xx 25)/350`
   = `1/7` sec.
2. Yes, as t= 0.143 s, and original sound persists only for 0.1 s.