[Codo]

Let's clear up the confusion.
No, I don't understand this either.
Maybe if I had some weeks to refresh my skills with theoretical mechanics, and nothing else to do.

But it illustrates the point: Seemingly simple mechanics can be extremely complex to describe and simulate. And this is just the physics/math behind this ONE THING.
So I guess that game engines use simplified physics or "cheat" physics instead of real movement equations.