Consider a laminar flow in the x-direction between two infinite parallel plates (Couette flow). The lower plate is stationary and the upper plate is moving with a velocity of 1 cm/ s in the x-direction. The distance between the plates is 5mm and the dynamic viscosity of the fluid is 0.01 N-s/mIf the shear stress on the lower plate is zero, the pressure gradient,  (in N/m² per m, round off to 1 decimal place) is______