Asteel frame supports a concrete mass, which in turn supports a exhaust fan. at a speed of 400 rpm, the amplitude of steady state vibration is 4 mm. at a speed of 500 rpm the amplitude of steady state vibration is 11.6 mm. if it is required that at the maximum turbine speed of 520 rpm the maximum steady-state amplitude be less than 2 mm, then the stiffness of the system needs to be changed. determine the minimum value of stiffness necessary for this design specification suppose the original stiffness of the system is k