A point charge 92 = -0.500 C is fixed at the origin of a coordinate system. Another point charge q = 1.50 C is initially located at point P, a distance d = 5.00 cm from the origin along the x axis. Point R is located on the x axis a distance d = 2.00 cm from the origin, as shown y R 91 92 -d2- P -d- The two charges q3 and 94 each have a magnitude of -0.250 C, half of that of 92. The charges are located a distance a = 1.20 cm from the origin along the y axis, as shown. T 93 a + a 194 ZOR x P d d- What is the potential energy U of the system composed of the three charges 91, 93, and 94, when q is at point R? Define the potential energy to be zero at infinity. U = J