Question

Two persons of masses $55\text{kg}$ and $65\text{kg}$ respectively, are at the opposite ends of a boat. The length of the boat is $3\text{m}$ and weighs $100\text{kg}$. The $55\text{kg}$ man walks up to the $65\text{kg}$ man and 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. Zero
• D. $0.75\text{m}$

Answer 1

The correct option is D. Zero.

Here on the entire system net external force is zero hence center of mass will be at rest and it remains unchanged. Thus the centre of mass of the system does not shift.