Question

A machine f mass 1000 kg is supported on springs which deflect 8 mm under static load with negligible damping of the machine vibrates with an amplitude of 5 mm when subjected to a vertical harmonic force at 80 percent of the resonant frequency. When the damper is fitted it is found that the resonant amplitude is 2 mm. Find ( I ) Amplitude of the damping force and ( ii ) damping co-efficient