\(F\,\, \times \,\, \bot \,\) અંતર \(r\,\, = \,\,I\,\,\alpha \)

\(  20\,\, \times \,\,R\,\, = \,\,\frac{{M{R^2}}}{2}\,\,\alpha \,\therefore \,R = 20\,\,cm\,\, = \,\,0.2\,\,M = \,\,0.20\,\,\)

\(\therefore \,\,20\,\, \times \,\,0.2\,\, = \,\,0.2\,\,\alpha  \)

\(  \alpha \, = \,\,20\,\,rad\,\,/\,\,{s^2}\,\,\therefore \,\,\omega \,\, = \,\,{\omega _0}\,\, + \;\,\alpha t \)

\(  \omega \,\, = \,\,0\,\, + \;\,20\,\, \times \,\,5\,\, = \,\,100\,\,rad\,/s  \)