A small sphere of mass m = 6.90 g and charge q1 = 32.1 nC is attached to the end of a string and hangs vertically. A second charge of equal mass and charge q2 = ?58.0 nC is located below the first charge a distance d = 2.00 cm below the first charge.If the string can withstand a maximum tension of 0.180 N, what is the smallest value d can have before the string breaks?