Two charges are located along the x-axis. One has a charge of 6.3 uC, and the second has a charge of -3.5 uC. If the electrical potential energy associated with the pair of charges is -0.044 J, what is the distance between the charges? The value of the coulomb constant is 8.98756 * 10 ^9 N * m^2 / C^2 and the acceleration due to gravity is 9.81 m/s^2. Answer in units of m.