The floor-to-ceiling distance in a certain room is h = 3.0 m. A spring with spring constant k = 560 N/m and relaxed length l = 13 cm is hung vertically from the ceiling of this room. Next, a marble with mass m = 17 g and charge q is hung from the bottom of the spring. Then, another marble with the same mass and charge magnitude (but opposite sign) as the first one is placed on the floor directly below the hanging marble. When the hanging marble reaches equilibrium, the spring has stretched by ?x = 7.0 cm from its relaxed length. What is the magnitude of q? For the limit check, investigate what happens to q if the spring becomes extremely stiff (i.e., k ? ?) but all other quantities remain the same. (Note: be careful not to confuse the spring constant k with the Coulomb constant ke.)