Two particles each have a mass of 5.8E-3 kg. One has a charge of +5.0E-6 C, and the other has a charge of -5.0E-6 C. They are initially held at rest at a distance of 0.70 m apart. Both are then released and accelerate toward each other. How fast is each particle moving when the separation between them is one-half its initial value? -- I've been trying a few steps to solve this question. I realize that I need to take a conservation of energy approach, where the Electrical Potential Energy initial = EPE final + KE final. I'm not sure, however, if I am missing any potential energies, and how to calculate the EPE. How would I mathematically differentiate between initial and final? Maybe someone can lead me in the right direction with how to calculate the EPE and confirm if my thinking up to this point is correct.