1. The problem statement, all variables and given/known data A proton is moving along the main axis of a uniformly charged thin ring. The charge density on the ring is 5.0 nC / cm and the ring radius is 1.0 cm. Initially the proton is 2.0 cm (along the axis ) from the center of the ring with the velocity towards the center of the ring. What initial speed should the proton have such it will cross the plane of the ring? im a little lost on this one. any help would be wonderful.