## Distribution (Dirac&standard) formulations of f=ma... how do they go again?

F - dp/dt give no component a distinct behaviour, but p = gamma m v does.

 Quote by James MC That is what I mean. I just don't understand how it follows. [i] If F=dp/dt is just shorthand for three separate equations for each component of force, then F=dp/dt entails that there is nothing special about one particular component. [ii] But there is something special about the component that is parallel to the velocity: there is more inertia in that direction. This argument against F=dp/dt contains only two premises, [i] and [ii], and is clearly valid. So either [i] or [ii] (or both) is false?
James, it gets worse. Align the force/change in momentum with the x-axis. Now the entire effect is in the direction of the x component, and ther is no effect in the y or z componnents!