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.