Water is moving through a pipe, and the laminar-flow velocity profile at some section is: V(r) = (Beta/(4*mu))((D^2 / 4) - r^2 ) t, V(r) is the viscosity of water, Beta is a constant, mu is the viscosity of water, D is the pipe diameter, and r is the radial distance from the pipe centerline. What is the shear stress in the fluid at the wall of the pipe? (Just use symbols.) If the given profile persists a distance L along the pipe, what is the force on the wall due to the moving water and what is its direction? (The force on the wall is equal in magnitude but in the opposite direction of that in the fluid.)