I just got A6 and have been playing with the physics but Im having a problem. I want to add to the force of the object in the direction its going, but I cant seem to get it to go anywhere but along a fixed axis. What it needs to do is increase in speed when it hits a certain object.

Any ideas?

EDIT: Also, is there anyway to constrain the object on one axis, for example if I dont want it to move on the Y axis or z axis?