Consider the two small, equal-mass, charged spheres shown in the figure. The top sphere is suspended from the ceiling by a string, and has a charge of 91 = -58.0 nC, and is directly below the top sphere. Assume d = 2.00 cm and m = 6.50 g. 92 = 30.5 nc. The bottom sphere has a charge of 91 + 92 (a) Calculate the tension (in N) in the string. N (b) If the string can withstand a maximum tension of 0.180 N, what is the smallest value d can have before the string breaks? (Give your answer in cm.) cm