A vibratory system with a moving base has a mass of 300 kg, a spring with a stiffness of 40000 N/m and a damper with an unknown damping constant. It is observed that the mass vibrates with an amplitude of 10 mm when the support oscillates with an amplitude of 2.5 mm at resonance (r=1) Determine:
(a) the damping coefficient
(b) the dynamic force amplitude acting on the base (Fr)