There is a boat 4m in length and mass 225 kg in still waters. a child skids in the boat and slips to the water at one end. seeing this the father at the other end runs with constant speed towards the child. If fathers mass is 75 kg how far would he be from where the child slipped?
If man's velocity is u and the boat's velocity in the opposite direction is v,
As the momentum is conserved,
(225+75)v = 75u
u = 300v/75 = 4v
Take the original position of one end of the boat as the origin, and the displacement of the boat (when the man has stopped running) is x. Thus, x = v*t, where t is the time consumed.
Consider the distance the man has traveled on the boat relative to the man
4 = ut thus t = 4/u
Therefore x = (u/4) (4/u) = 1
The displacement is 1 meter