An unbalanced engine mounted on an elastic support imposes aperiodic vertical force on the support at the rotational frequencyof the engine. In order to determine the relationship between theengine rotational frequency and the resonance frequency of theelastically supported engine, the engine run speed was slowlyincreased from its normal value of 550 rpm to 825 rpm, whichresulted in a trebling of the amplitude of the measureddisplacement. No resonance was observed in the displacementresponse in the range of speeds investigated. Assuming that thedamping present in the existing elastic support is negligible,determine: The natural frequency of the elastically supportedengine is ----- rad/s?
