Problem 1.331

A thin horizontal disc of radius $R=10 \mathrm{~cm}$ is located within a cylindrical cavity filled with oil whose viscosity $\eta=0.08 \mathrm{P}$ (Fig. 1.89). The clearance between the disc and the horizontal planes of the cavity is equal to $h=1.0 \mathrm{~mm} .$ Find the power developed by the viscous forces acting on the disc when it rotates with the angular velocity $\omega=60 \mathrm{rad} / \mathrm{s}$. The end effects are to be neglected.