# Homework Help: Find the final momentum

1. Nov 5, 2008

### ScullyX51

1. The problem statement, all variables and given/known data

A red ball is heading due east, a blue ball is moving due west, and a green ball is moving north. They have initial speeds vr,i=20 cm/s, vb,i=10 cm/s, vg,i=10 cm/s. The red ball has a mass of 5 g, the blue ball has a mass of 10g, and the green ball has a mass of 5g. The three balls all collide, and stick together. Find the magnitude and direction of the final momentum of the composite.

2. Relevant equations
the sum of PI=the sum of PF

3. The attempt at a solution
Ok...without plugging the numbers in this is what I have so far:
I don't really know how to approach this problem, so if someone could tell me if I am starting it on the right path would be great.
I broke it up into x and y components, and for the x component of momentum I have:
MBVB-MRVR=(MR+MB+MG)VFX)

Then for the y component I have:
MGVG=(MR+MB+MG)VFY)

Am I on the right track...or completely missing the point?
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Nov 6, 2008

### tiny-tim

Hi ScullyX51!
Yes, that is exactly the right track …

momentum is a vector, and so it obeys the laws of vector addition …

sometimes physics is that easy!