Question

A uniform disk of mass m and radius r is released from the shown position. Pq is a string, op is a horizontal line, o is the centre of the disc and distance op is r/2

Answer 1

Please go through the solution in the picture

Answer 2

The tension in the string is 2mg/3.

Mass of the disk = m (Given)

Radius of the disk = r (Given)

String = PQ  (Given)

OP is a horizontal line O (Given)

Applying Newton's law on the centre of mass O

ma = Mg−T where a is the acceleration of the centre of mass  

τ = Iα which is about centre of the mass

T = R/2 = MR²/2 × α

As a = R/2α, then from above equations

T = 2mg/3