Two persons of masses $55 \mathrm{~kg}$ and $65 \mathrm{~kg}$ respectively, are at the opposite ends of a…

Two persons of masses $55 \mathrm{~kg}$ and $65 \mathrm{~kg}$ respectively, are at the opposite ends of a boat. The length of the boat is $3.0 \mathrm{~m}$ and weighs $100 \mathrm{~kg}$. The $55 \mathrm{~kg}$ man walks up to the $65 \mathrm{~kg}$ man and sits with him. If the boat is in still water the centre of mass of the system shifts by
  1. $3.0 \mathrm{~m}$
  2. $2.3 \mathrm{~m}$
  3. zero
  4. $0.75 \mathrm{~m}$

Solution

Here on the entire system net external force on the system is zero hence centre of mass remains unchanged.

Asked in: NEET 2012 (Screening)

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