1. The problem statement, all variables and given/known data What will be the final velocity of a proton (when it is very far away) if it it released from rest at the center of a uniformly charged hoop and given a slight push in one direction. assume it follows the axis of the hoop. mass of proton: m = 1.67x10-27 kg charge of proton: q = 1.6x10-19 C radius of hoop: R = 1 cm charge of hoop: Q = 1 nC 2. Relevant equations λ = Q/2πR k = 9 x 109 E = kλx2πR/(x2+R2)3/2 F = Eq 3. The attempt at a solution λ = 9x10-9 / 2π(.01) = 1.59 x 10-8 C/m I know that the force and acceleration will vary with the distance from the hoop x, but I don't know how to find the final velocity. I was thinking maybe you have to find the potential energy of the proton before it starts moving and then use that as its final kinetic energy to find velocity? I don't know how to find electrical potential energy though.