Chapter 22, Problem 32AP

A small sphere of charge q₁ = 0.800 μC hangs from the end of a spring as in Figure P22.32a. When another small sphere of charge q₂ = −0.600 μC is held beneath the first sphere as in Figure P22.32b, the spring stretches by d = 3.50 cm from its original length and reaches a new equilibrium position with a separation between the charges of r = 5.00 cm. What is the force constant of the spring?

Figure P22.32