okay there are several problems in my physics book that really have me stumped. I just want to learn a method of solving them. basically they have to do with a sphere of a given diameter and charge. The problem then says assume a subatomic particle (electron or proton) is placed on the sphere and the sphere is charged to the same charge(ie if the particle was a proton the charge on the sphere would be positive). The charge on the sphere is much higher than on the particle. then it asks how fast is the particle moving away from the sphere at a given distance away. I would really appreciate any hints or formulas that I could use to solve these types of problems.