S Review. Two identical particles, each having charge +q , are fixed in space and separated by a distance. D. A third particle with charge -Q is free to move and lies initially at rest. On the perpendicular bisector of the two fixed charges a distance x from the midpoint between those charges (Fig. P23. 14). (c) How fast will the charge -Q be moving when it is at the midpoint between the two fixed charges if initially it is released at a distance a<