Ok Erik er...Dennis. All that does is recognize there is a force going out and potentially one coming in. It doesn't recognize how the force is being generated in, and from, i. Nor how it is either being met, changed, or redirected...within...the body of j.
Which is the heart of the matter since the results- changes everything.
Dan my boy, There is a model for that and it is called the Friction Factor but all this logic gets in the way of the human factor and we just can't model it very well. We can predict it somewhat but we just can't model model it with a hoot. .