- L.J PUIILD EE EPE and Speed of Proton in an electric field A Proton of charge +1e, as shown in Figure 5 below, is located 1.0 m from a point charge of + 3.5 x 1076 C. The Proton, initially at rest at Point X, is released and at Point Y reaches a velocity v at Point Y. What is the value of v? +3.5x107C Proton 2o Fixed charge X Y e1.0m e 2. 0m > Figure 5 Note: Charge of a proton equals + 1.6 x 1019 , Mass of proton equals 1.673 x 10'27kg. Strategy for solving the problem: The types of energy involved here are EPE (electrical potential energy) of the proton due to the Point Charge (g) and the kinetic energy of the proton. We then use Conservation of Energy principles to solve for the unknown variable v