A 200-lb motor is supported by two springs, each of constant 15 kips/ft, and is connected to the ground by a dashpot having a coefficient of damping c = 490lb ‹… s/ft. The motor is constrained to move vertically, and the amplitude of its motion is observed to be 0.10 in. at a speed of 1200 rpm. Knowing that the weight of the rotor is 30 lb, determine the distance between the mass center of the rotor and the axis of the shaft.