Answer:
1.457881265 kgm²
0.02842 Nm/rad
0.13962 rad/s
Step-by-step explanation:
M = Mass = 3.97 kg
R = Radius = 85.7 cm
= Torque = 0.0688 Nm
= Angle of rotation = 2.42 rad
Moment of inertia about the center of the disk is given by

The rotational inertia of the disk about the wire is 1.457881265 kgm²
Torque is given by

The torsion constant is 0.02842 Nm/rad
Time period is given by

Angular frequency is given by

The angular frequency of this torsion pendulum when it is set oscillating is 0.13962 rad/s