Calculate the minimum distance at which a person should stand in front of a reflecting surface so that he can hear a distinct echo. (Take the speed of sound in the air $= 350 m s^{- 1}$ )

Question

Q.

At $20^{o} C$ , the minimum distance of a person from a sound reflecting surface to hear an echo is :

(a) 12.2 m

(b) 17.2 m

(c) 15.2 m

(d) 34.4 m

Answer 1

s=dt⇒d=s×t=350×0.12=17.5ms=dt⇒d=s×t=350×0.12=17.5m

Calculate the minimum distance at which a person should stand in front of a reflecting surface so that he can hear a distinct echo. (Take the speed of sound in the air =350ms−1)