Right. Would have to take the absolute value. Also guess it would have to be relative to the other object's velocity as well, since there will be two moving bodies.
delta(abs(x) + abs(y)) would get the relative velocity, then plug that into for both objects with their masses to figure out the force imparted on the other.
That makes sense, for what little Physics I remember from 2 decades ago in the classroom.
Edit: Also, before I make some poor physics major's head explode, I realize now after more research that I'm wanting momentum (P=mv) and not Force (F=ma).
Right method, wrong formula.