Question

Two persons A and B having masses $55\text{kg}$ & $65\text{kg}$ respectively, are sitting at the opposite ends of a stationary boat. The length of the boat is $3\text{m}$ and the weight is $100\text{kg}$. Person A walks upto person B & sits with him. If the boat is in still water, the centre of mass of the system shifts by

• A. $3\text{m}$
• B. $2.3\text{m}$
• C. $0\text{m}$
• D. $0.75\text{m}$

Answer 1

The correct option is C $0\text{m}$

Initially both persons and the boat are at rest.Therefore C.O.M of the system is also at rest.
$\Rightarrow \overrightarrow{v_{com}}=0$
As there is no external force acting on the system, $\overrightarrow{a_{com}}=0$

Therefore, C.O.M of the system will continue to remain at rest and it will not shift.