$0\mathrm{.}3$m diametercircularplateisplacedoverafixedbottom plate with a $0\mathrm{.}0025$m gap between the two plates filled with glycerin as shown in Fig. P$1\mathrm{.}89.$ Determine the torque required to rotate the circular plate slowly at $2$ rpm$.$ Assume that the velocity distribu$-$ tion in the gap is linear and that the shear stress on the edge of the rotating plate is negligible.