Two particles each have a mass of 6.1 x 10-2 kg. One has a charge of +4.1 x 10-6 C, and the other has a charge of -4.1 x 10-6 C. They are initially held at rest at a distance of 1.0 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?