From the given figure, the axis of rotation is a horizontal line passing through the point A on the edge of the disc. The circular arrow around the axis indicates that the disc oscillates out of its plane, meaning the axis of rotation is a tangent to the disc in its own plane.
The moment of inertia of a uniform disc about its diameter is Icm=41MR2.
Using the parallel axis theorem, the moment of inertia of the disc about the given axis of rotation is:
I=Icm+MR2=41MR2+MR2=45MR2
The distance from the center of mass of the disc to the axis of rotation is d=R.
The time period of a physical pendulum is given by:
T=2πMgdI
Substituting the values of I and d:
T=2πMgR45MR2=2π4g5R
Answer: 2π4g5R
