The first Stokes problem is defined as one that describes the abrupt movement at constant speed of a flat plate in an incompressible Newtonian fluid (transient Couette without pressure gradient in the direction of movement). Consider a fluid at rest on a flat horizontal plate before motion. At instant t=0 the plate begins to move at a constant speed U. Assume that the fluid has a kinematic viscosity v. The flow induced in the fluid is only caused by viscous stresses. a) Simplify the Navier-Stokes equations for this case.