When the motor is slowly brought up to speed, a rather large vibratory oscillation of th...

When the motor is slowly brought up to speed, a rather large vibratory oscillation of the entire motor about O-O occurs at a speed of 360 rev/min, which shows that this speed corresponds to the natural frequency of free oscillation of the motor. If the motor has a mass of 43 kg and radius of gyration of 100 mm about O-O, determine the stiffness k of each of the four identical spring mounts.