Help with Final Velocity Collision Problem

[Lori]

Homework Statement

Homework Equations

change in momentum = m1v1 = m1v1+m2v2
center of mass = m1x + m2x / (total mass)

The Attempt at a Solution

m1v1= m2v2 + m3v3
m1 = 2
v1 = 4
m2 = m1 divided by 2
m3 = m3 divided by 2[/B]

2*4 = 1*12 + 1v3
v3 = -4
v3= -4? in the x directioncenter of mass velocity would be (treating velocities as x?)
v of center mass = (-4*1 + 12*1)/2 = 4 , in the +x-direction

 

[haruspex]

v3= -4? in the x direction

Yes (answer (f)).