Two particles of masses m and 3m approach each other with different velocities. After collision, the particle of mass m has velocity `vec( v) ` in their centre of mass frame. Velocity of particle of mass 3m in the centre of mass frame is

Options

A. `- 2 vec( v ) `
B. ` - ( vec(v))/(2)`
C. `-( vec( v ))/(3)`
D. `( vec( v ))/(4)`

Answer

C