(1) A cubic block of mass M with sides of length a slides across a flat plate on a thin film of oil. The oil has viscosity u and the film has a thickness of h. The block moves at a steady speed of U under the action of a constant force F. What is the magnitude and direction of the shear force on the bottom of the block and on the plate? If the force F is suddenly removed and the block slows down, obtain an expression for the time taken for the block to lose 95% of its original speed. Recall that acceleration = dU/dt. [t= 3.0 Mh/ua]