I don't understand the question.
That's exactly why I asked you.
We only talk about aikido here.
Well, take e.g. a resisting partner in a static position and the main forces affect your partner in one single plane. Then you could say you simply project ki, like Tohei would, or you may resort to ground-path and structure, and a simple vector model, like M.Sigman did, to let a beginner get a foot in the door to internal training. You would expect and feel a resisting force, which is obvious to you and it would make no difference if it were based on an internal or external paradigm.
Are we still on common ground? If so, have a look and try to see what you can get.
F1 = G1 x l1/h1
F2 = G2 x l2/h2
Equilibrium: F1 = F2 and G1x l1/h1 = G2 x l2/h2
If G1 > G2 then the value of l2/h2 has to increase:
Either you increase the value of l2, e.g. you take a step backwards,
Or you decrease the value of h2 by lowering your centre of mass,
one after the other or simultaneously.
Now, take someone with more advanced internal ability, who resists the push, as described in "Aikido and the dynamic Sphere" (Ratti/Ratti), using stillness in motion and intent to create a dynamic sphere, still not moving visibly. You will probably meet and feel a wobbly soft and cloudy thing, with the effect that you can't make head and tail of it until you find yourself on the ground, wondering how that could possibly have happened.
I suppose, that to describe this with a simple physical model will be more difficult than describing how to ride a bicycle. If you attempt this, then good luck.