The Evolution of Momentum

In the old sense of momentum is just mass times velocity then it all made sense and then you get the equation f equals ma. But when we change the definition of momentum you no longer have f equals ma so there's sort of a choice to be made there like do you redefine momentum or doyou redefine mass? The modern idea that most physicists use is exactly that I say let's just leave mass alone mass is related to your internal stored energyLet's define mass to be something everybody agrees on no matter what their velocity is"