Question

Mr Verma ($50kg$) and Mr Mathur ($60kg$) are sitting at the two extremities of a $4m$ long boat ($40kg$) standing still in water. To discuss a mechanic problem, they come to the middle of the boat. Neglecting friction with the water, how far does the boat move on the water during the process ?

Answer 1

Given, Mr Verma and Mr Mathur are at the extreme position of the boat.

Centre of mass $=\frac{60\times 0+40\times 2+50\times 4}{150}=\frac{280}{150}=1.87$

Centre of mass will be at a distance of $1.87$ from point $A$ which is the origin of the system .

So, when both come to the midpoint of the boat the centre of mass lies at $2m$ from $A$.

Shift in centre of mass $=2-1.87=0.13m$ towards right.