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Two particles A and B initially at rest,...

Two particles `A` and `B` initially at rest, move towards each other, under mutual force of attraction. At an instance when the speed of `A` is `v` and speed of `B` is `2v`, the speed of centre of mass (`CM`) is

A

3V

B

V

C

1.5 V

D

zero

Text Solution

Verified by Experts

The correct Answer is:
D
(d) We know that `F_(ext) = Ma_(c.m) …(i)`
We consider the two particles in a system. Mutual force
of attraction is a internal force. There are no external
forces acting on the system. From (i)
`a_(c.m) = 0 rArr v_(c.m) = constant.
Since, initially the `v_(c.m) = 0`
`:. Finally `v_(c.m).`
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