A man standing in front of a hill produces an articulate sound and hear its echo after 4.5s. He then moves 250m towards hill and produces the same sound. Its echo is now heard after 3.1s. Find original density of man from hill and velocity of sound.
Let the man is standing at a distance 'x' m from hill and speed of sound in air 'v' m/s.
Distance covered by sound = 2x m
Time taken = 4.5 s
second case: Man has travelled 250 m towards hill.
Distance covered by sound = (x-250) m
Time taken = 3.1 s