Solve the following problem given below:
Problem: Determine the natural frequency of torsional vibration of a 0.8m diameter disc mounted on a steel shaft of .04 m diameter and 2 m length. The thickness of the disc is 0.1 m and both shaft and disc are made of steel for which the shear modules equal to 77GPa and density is equal to 7800 kg/m3.
Please explain each step and equations used for above problem.