Question

A uniform disc of mass $M$ and radius $R$ is mounted on an axle supported in frictionless bearings. A light cord is wrapped around the rim of the disc and a steady downward pull $T$ is exerted on the cord. The angular acceleration of the disc is

• A. $\frac{T}{MR}$
• B. $\frac{MR}{T}$
• C. $\frac{2T}{MR}$
• D. $\frac{MR}{2T}$

Answer 1

Answer: (C)

$\frac{2T}{MR}$

$TR=I\alpha where,I=\frac{M{R}^2}{2}\alpha =\frac{TR}{\frac{M{R}^2}{2}}=\frac{2T}{MR}$