A particle of mass m moving with velocity u collides elastically with a particle of mass 3m at rest. After collision the heavier particle moves with velocity.

A particle of mass m moving with velocity u collides elastically with

1.	A particle of mass m moving with velocity u collides elastically with a particle of mass 3m at rest. After collision the heavier particle moves with velocity.
Answer» 3 U `(u)/(3)` `(u)/(2)` 2u Answer :C