A $1\mathrm{.}2$ m diameter solid Disk rotates about an axis through its center by torque of

$80\mathrm{.}0$ m$.$N which accelerates it uniformly from rest through a total of $800$ revolutions

in $30\mathrm{.}0$ second. What is the mass of the disk? Moment of Inertia for a disk is

I$=1/2$ MR$2$

$.$