• # question_answer A shaft, supported on two bearings at its ends, carries two flywheels 'L' apart. Mass moment of inertia of the two flywheels are ${{l}_{a}}$ and ${{l}_{b}}$ I being the polar moment of inertia of cross-sectional area of inertia of shaft. Distance ${{l}_{a}}$ of the node of torsional vibration of the shaft from the flywheel la is ${{l}_{a}}$ given by:  A) ${{l}_{a}}=\frac{L{{l}_{b}}}{{{I}_{a}}+{{I}_{b}}}$                       B) ${{l}_{a}}=\frac{L{{l}_{a}}}{{{I}_{a}}+{{I}_{b}}}$C) ${{l}_{a}}=\frac{L{{l}_{b}}}{{{I}_{a}}+{{I}_{b}}-1}$        D) ${{l}_{a}}=\frac{L{{l}_{a}}}{{{I}_{a}}+{{I}_{b}}-1}$

${{I}_{a}}=\left( \frac{{{I}_{b}}}{{{I}_{a}}+{{I}_{b}}} \right)\,L$