Question

A uniform thin ring of radius r and mass m suspended in a vertical plane

Answer 1

A uniform thin ring of radius r and mass m suspended in a vertical plane

The above term is known as Physical Pendulum, it is a kind of pendulum where an object don't consider a point but it is extended in a mean of size and shape.

and the formula to calculate time period is T=2xpixroot( I / mgL)

I ===> moment of inertia

L ===> distance between pivot point &  center of mass.