A single degree of freedom damped spring mass system is subject to base excitation. The system properties are Mass m = 1000 kg Natural frequency fn = 0.1 Hz Damping ratio zeta = 0.2 Excitation displacement 1mm at a frequency f = 0.12 Hz What is the amplitude of the response in mm?https://www.dropbox.com/s/0u2aliiovs...5833s.jpg?dl=0

I found H(ω) but I don't know how to find Force F in order to calculate A=F*H(ω)?

I couldn't upload a picture with my workings so used dropbox:

Thanks in advance