Question

An observer stands at a distance of 850m from a cliff and fires a gun. After what time gap will he hear the echo? If sound travels at a speed of 350m/sec., in air. 

Answer 1

Given:

d = 850meter,

t = ?

speed v = 350m/sec

∴ t = 2d/v

⇒ t = (2 x 850)/350 ⇒ t = (2 x 17)/7 = 4.86sec.