Sun February 24, 2013 By:

maam i have a question. A person of mass 80 kg is standing on a boat of mass 200kg. Length of the boat is 5m. Person walks to the other end of the boat. Find the shift in centre of mass of the system. and shift in the centre of mass of the boat.

Expert Reply
Mon February 25, 2013
The center of mass of boat does not change because it is fixed. We are not changing the geometry of the boat.
It will remain at the boat's center.
Thus Initial center of mass will be at:
Let center of mass of boat be at origin, thus one end of boat is at -2.5m and other at +2.5m
let the man initially be at -2.5m
thus center of mass:
x= [80(-2.5) + 200(0)]/(80+200) = -0.71m
after he walks to the other end, due to symmetry it changes to +0.71 m 
thus shift ~ 1.42 m
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