Question

Sunil is standing between two walls . The wall closest to him is at a distance of 360 m. If he shout,he hears the first echo after 4 seconds and another after 2 seconds. What is the velocity of sound in air? What is the distance between two walls?

Answer 1

180 okay okay okay okay

Answer 2

Distance between the closest wall and Sunil = 360mTime after which he hears echo = 4sVelocity of sound = 2(Distance/time)                            = 360*2/4                             = 180m/sLet distance between two walls be (x)m Distance of another wall from Sunil = (x - 360)mTime after which he hears echo = 4s + 2s = 6sVelocity of sound = 2(Distance)/time                            = 2(x-360)/6Hence,180 = 2(x-360)/6 (Velocity of sound remains constant)⇒1080 = 2(x-360)⇒540 = x - 360⇒x = 540 + 360Distance between two walls=900m