The weight of an electric motor is 125 N and it runs on 1500 rpm. The armature weighs 350 N and its centre of gravity lies 0.05 cm from the axis of rotation. The motor is mounted on five springs of negligible damping so that the force transmitted is one-eleventh of the impressed force. Assume that the weight of motor is equally distributed among the five springs. Determine:

a. Stiffness of each spring.

b. Dynamic force transmitted to the base at operating speed.

c. Natural frequency of the system