Problem 2 free torsional vibration of two rotor system, torsionally equivalent shaft

A shaft shown in diagram carries two rotors A and B. The mass of rotor A is 300 kg with radius of gyration of 0.75 m, while the mass of rotor B is 500 kg with radius of gyration of 0.9 m 1. Find the natural frequency of torsional vibration. 2. It is desired to have the node at mid section of the shaft of diameter 120 mm by changing the diameter of the portion of shaft having 90 mm diameter. What would be the new diameter? Assume G = 84× 10^9 N/m^2 Please refer my following Playlists , Links are given: 1. Theory of Machines or Kinematics of Machines play list    • Theory Of Machines playlist   2. Fluid mechanics and Hydraulic machines playlist    • Fluid mechanics and hydraulic machines   3. Refrigeration and air conditioning playlist    • Refrigeration and air conditioning   4. Renewable Energy engineering or Non-convensional energy sources play list    • Renewable energy engineering/ Non-conventi...   5. Dynamics of Machinery play list    • Dynamics of machinery / Mechanical Vibrati...   6. Engineering graphics or Engineering drawing play list    • Engineering Graphics Playlist   7. Engineering Mechanics Playlist    • Engineering Mechanics Playlist   8. Power plant engineering play list    • Power Plant Engineering( Mechanical Branch...   9. Engineering Thermodynamics play list    • Thermodynamics / Thermal Engineering   Pla...   10. Heat and mass transfer play list    • Heat and Mass Transfer Playlist   11. Operation research play list    • Operation Research Playlist   12. Strength of material playlist    • Strength Of Materials Play list   13. Control Engineering/ Control systems engineering playlist    • Control Systems playlist ( EnTC & Mechanic...