I am studying this paper:
Noether's theorem and the work-energy theorem for a charged particle in an electromagnetic field | DeepDyve
and he makes a step that seems wrong to me, but the final answer can't be wrong so I am confused.
he then effectively says
Whereas I get
I have attached a piece of the paper incase you want to see where this came from. Here, Zeta is the position vector x and tau is the time t.
Am I missing something here?