Do you split your car velocity into roughly estimated x,y,z components? Or just take it as an integrated accurate more or less value?
Or when you walk along the street and a little to right hand, and then continue walking this street and a little to left hand, do you invert the sign of you cross speed, or just rotate your.total speed vector several degrees to the left?
So, the uncertainty appears when you split the integrated "momensition" into x,y,z,t components.
(In fact, the 1st year of theoretical mechanics course implements "action" , then you study Hamilton's principle, and the world will never be the same).
Just must clear: there is no such thing as "momensition" in physics, it's a joke.