Question

A $10kg$ boy is standing on a boat of mass $40kg$ floating in water such that the boy is $20m$ from the shore. If the boy walks linearly $8m$ on the boat towards he shore and stops (with respect to shore), then how far the boy will be from the shore? (neglect friction between boat and water).

Answer 1

Mass $=10$ Kg.

To keep centre of mass at rest as to net external forces is zero so the boy would move $\delta -x$ displacement and boat would move $x$ displacement on the opposite direction. So,

$10\times (\delta -x)=40\times \left(x\right)$

So, $x=1.6m$

$s-1.6m=6.4m$

So,

distance from boat

$20.64$

$=13.6m$