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. `T/(MR)`
B. `(MR)/T`
C. `(2T)/MR`
D. `(MR)/(2T)`

Answer 1

Correct Answer - C
Torque exerted on the disc
`tau=TR`
Now `tau=Ialpha`
`alpha=tau/I=(TR)/(1/2MR^(2))`
`(2TR)/(MR^(2))=(2T)/(MR)`