Two particles which are initially at rest, move towards each other under the action of their internal…

Two particles which are initially at rest, move towards each other under the action of their internal attraction. If their speeds are $\mathrm{v}$ and $2 \mathrm{v}$ at any instant, then the speed of centre of mass of the system will be
  1. $2 \mathrm{v}$
  2. 0
  3. $1.5 \mathrm{v}$
  4. $\mathrm{v}$

Solution

As initially both the particles were at rest therefore velocity of centre of mass was zero and there is no external force on the system so speed of centre of mass remains constant $i e$, it should be equal to zero. ~

Asked in: NEET 2010 (Screening)

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