$2.$ A vibration isolation block is to be installed in a laboratory so that the vibration from adjacent factory operations will not disturb certain experiments $($Fig$.$ P$3\mathrm{.}15).$ If the isolation block weighs $2000$ lb and the surrounding floor and foundation vibrate at $1500$ cycles per minute, determine the stiffness of the isolation system such that the motion of the isolation block is limited to $\backslash (10\backslash \%\backslash )$ of the floor vibration; neglect damping.