A body A of mass M while falling vertically downwards under gravity breaks into two-parts; a body B of mass 1/3M and a body C of mass 2/3M. The center of mass of bodies B and C taken together shifts compared to that of body A towards (a) does not shift (b) depends on height of breaking (c) body B (d) body C

Answer: (a). Breaking up is due to internal forces; the only external force is still gravity Mg. So acm = g before and after, and the CM motion is unchanged. So the answer is (a) the centre of mass does not shift.

A body A of mass M while falling vertically downwards under gravity… | JEE Main 2005 (AIEEE)

Q13JEE Main 2005 · AIEEEEasy

Motion of Centre of Mass

A body $A$ of mass $M$ while falling vertically downwards under gravity breaks into two-parts; a body $B$ of mass $\frac{1}{3}M$ and a body $C$ of mass $\frac{2}{3}M.$ The center of mass of bodies $B$ and $C$ taken together shifts compared to that of body $A$ towards

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Answer: (a)

Breaking up is due to internal forces; the only external force is still gravity $Mg$ .
So $\vec{a}_{cm} = \vec{g}$ before and after, and the CM motion is unchanged.
So the answer is (a) the centre of mass does not shift.

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