Since the kinetic energy theorem has total work=1/2mv?-0 0 0 means the initial velocity is 0 so the initial kinetic energy is 0
So average power=N-1/2mv?/t I think the N here stands for the number of protons that leave the gas pedal at time t as set by lz
Kinetic energy theorem solves for the problem of knowing the velocity. Very handy I hope it helps