When a \(40-\mathrm{kg}\) machine is placed on an elastic foundation, its free vibrations appear to decay exponentially with a frequency of \(91.7 \mathrm{rad} / \mathrm{s}\). When a \(60-\mathrm{kg}\) machine is placed on the same foundation, the frequency of the exponentially decaying oscillations is \(75.5 \mathrm{rad} / \mathrm{s}\). Determine the equivalent stiffness and equivalent viscous damping coefficient for the foundation.