where use has been made of the Pythagorean theorem. Likewise, the absolute electric potential of the third charge due to the presence of the second charge is

The net absolute potential of the third charge is simply the algebraic sum of the potentials due to the other two charges taken in isolation. Thus,

The change in electric potential energy of the third charge as it moves from its initial
position to infinity is the product of the third charge, , and the difference in electric
potential () between infinity and the initial position. It follows that

This decrease in the potential energy of the charge is offset by a corresponding increase in its kinetic energy. Since the initial kinetic energy of the third charge is zero (because it is initially at rest), the final kinetic energy is simply