The force transmitted by an internal combustion engine of mass \(500 \mathrm{~kg}\), when placed directly on a rigid floor, is given by

\[F_{t}(t)=(18,000 \cos 300 t+3600 \cos 600 t) \mathrm{N}\]

Design an undamped isolator so that the maximum magnitude of the force transmitted to the floor does not exceed 12,000 N.