Mathematical vectors

I am looking for info on vectors in Flash, but not the graphical kind. The kind that deals with physics. The reason is, I just finished developing a 1D elastic collision file, and I want to move on to 2D collisions, which requires transfer of direction, as well as speed.

The velocity transfers are pretty easy, its the vectors that throw me off. I thought about getting the slope of the line it follows, then picking out the individual X and Y components of the ball in motion and applying them to the next ball, but then theres the whole issue of reflection and things like that. Any ideas?