A body A of mass M while falling vertically downwards under gravity breaks into two parts; a body B of mass 1 / 3 M and a body C of mass 2 / 3 M . The centre of mass of bodies B and C taken together shifts compared to

Correct answer: B. does not shift No horizontal external force is acting aligned & a_ cm =0 & since v_ cm =0 & Δ x_ cm =0 aligned

JEE Main 2005

JEE Main 2005 · Physics · Center of Mass, Momentum and Collision

A body A of mass M while falling vertically downwards under gravity...

A body

A

of mass

M

while falling vertically downwards under gravity breaks into two parts; a body B of mass

1 / 3 \mathrm{M}

and a body

\mathrm{C}

of mass

2 / 3 \mathrm{M}

. The centre of mass of bodies

\mathrm{B}

and

\mathrm{C}

taken together shifts compared to that of body

\mathrm{A}

towards

B. does not shift

No horizontal external force is acting

\begin{aligned}& \therefore \mathrm{a}_{\mathrm{cm}}=0 \\ & \text{ since } \mathrm{v}_{\mathrm{cm}}=0 \\ & \therefore \Delta \mathrm{x}_{\mathrm{cm}}=0 \end{aligned}