This system may, for vibration analysis be treated as being on one shaft (integral with ) if

Question

Suppose two rotors with inertias I₁ and I₂ on shafts of lengths  respectively are connected by gears such that the speed of the I₂ rotor is always G times that of the I₁ rotor. This system may, for vibration analysis be treated as being on one shaft (integral with ) if

         (a) I₁₌is changed to G² I₁           (b) I₂ is changed to G²I₂

         (c) I₁ is changed to I₁/G²            (d) I₂ is changed to I₂/G²