Question

A man standing in front of a vertical.cliff fires a gun. He hears the echo after 4 s. On moving closer to the cliff by 70 m, he fires again and hears the echo after 2 s. Find: I. The distance of the cliff from the initial position of the man and II. The velocity of sound.​

Answer 1

Answer:

(i)140m

(ii)70m/s

Explanation:

Let initial distance be d and velocity of sound be v

v=d/t

v=2d/4

v=d/2. (i)

Now,

d'=d-70. t'=2s

v=2(d-70)/2

v=d-70

d/2=d-70. {from (i)}

d=2d-140

d=140m

Therefore,

velocity of sound=140m/2s

v =70m/s