Oil with a density of 850 kg/m and viscosity of 1.510 2 Pas occupies the space between two concentric cylinders. The inner cylinder has a diameter of D i =3cm. The outer cylinder has a diameter of Do =4cm. The inner cylinder is held stationary. The length of both cylinders is 1m. Determine the force required to rotate the outer cylinder with a tangential velocity of 0.15 m/s 1