A proton and an electron are traveling in the uniform magnetic field with identical velocities. If the movement of both particles is perpendicular to the magnetic field lines, which of the following is NOT true? I. The acceleration of the proton is greater than the acceleration of the electron II. The proton will experience a greater kinetic energy change than the electron III. The magnetic force on both particles is 0 A. III only B. I and III only C. II and III only D. I, II, and III The answer is D. I thought the answer was B because KE = 1/2mv^2 so I figured that the proton would have a greater kinetic energy. The explanation is that the force doesn't do work and therefore can't change the kinetic energy of either particle. Can someone explain this in another way to me please? I get why I and III are false, but I don't get why II is false.