Collision for a line?

Okey, I have two particles (mc’s) that are linked together to a line. Both particles use xspeed and yspeed when they are moving.

Then to my question… how will the particles xspeed/yspeed change when the line collide into another movieclip?

I know how I can check the collision, but I don’t know how I’m going to change the speeds.

I have to use (in the very collision moment);

particle_1’s xspeed/yspeed
particle_2’s xspeed/yspeed
the lines rotation
the direction the line came from
the length of the line
where on the line it collides

Please help!