A sensitive instrument of mass \(100 \mathrm{~kg}\) is installed at a location that is subjected to harmonic motion with frequency \(20 \mathrm{~Hz}\) and acceleration \(0.5 \mathrm{~m} / \mathrm{s}^{2}\). If the instrument is supported on an isolator having a stiffness \(k=25 \times 10^{4} \mathrm{~N} / \mathrm{m}\) and a damping ratio \(\zeta=0.05\), determine the maximum acceleration experienced by the instrument.