Two particles each have a mass of 5.3 10-3 kg. One has a charge of +5.0 10-6 C, and the other has a charge of -5.0 10-6 C. They are initially held at rest at a distance of 0.75 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? ok, I know: q1 = +5.0 x 10^-6 C q2 = -5.0 x 10^-6 C r = 0.75m m = 5.3 x 10^-3 kg Since they are opposite charges they will atract eachother. I can't seem to figure out where to begin on what formula to use to discover the speed without any time.