(a) Water flows between two large flat plates. The lower plate moves to the left at a speed of 0.3ms1; the upper plate is stationary. The plate spacing is 3mm and the flow is laminar. Determine the pressure gradient required to produce zero net flow at any cross-section. Navier-Stokes equation in x direction (tu+uxu+vyu+wzu)=gxxP+(x22u+y22u+z22u) where u,v and w are the x,y and z components of velocity