What torque will increase angular velocity of a solid disc of mass 16kg and diameter 1 m from zero to 2 rpm in 8 s ?

Options

A. `((pi)/(4))N-m`
B. `((pi)/(2))N-m`
C. `((pi)/(3))N-m`
D. `(pi)N-m`

Answer

D

Explanation

As, `l=(1)/(2)mr^(2)=(1)/(2)xx16((1)/(2))^(2)=2kg-m^(2)`
`alpha=(2pi(n_(2)-n_(1)))/(t)`
`=(2pi(2-0))/(8)=(pi)/(2)"rad s"^(-2)`
`"Now, "tau=l alpha=2.(pi)/(2)=piN-m`