A solid cylinder of mass `50 kg` and radius `0.5 m` is free to rotate about the horizontal axis. A massless string is wound round the cylinder with one end attached to it and other end hanging freely. Tension in the string required to produce an angular acceleration of `2` revolution `s^(-2)` is

Options

A. `50 N`
B. `78.5 N`
C. `157 N`
D. `25 N`

Explanation

Taking torque about `O`, we get
`TR= I alpha =(1)/(2)MR^(2) alpha`
`T=(1)/(2)MRalpha`
`M=50 kg, R=0.5m, alpha=2xx2pi=4pi rad//s^(2)`
`T=(1)/(2)xx50xx0.5xx4pi= 50pi=50xx3.14`
`=157 N`