Question

Consider the steady, uni-directional, fully-developed, pressure-driven laminar flow of an incompressible Newtonian fluid through a circular pipe of inner radius 5.0 cm. The magnitude of shear stress at the inner wall of the pipe is $0.1 N/m².$ At a radial distance of 1.0 cm from the pipe axis, the magnitude of the shear stress, in $N/m²,$ rounded off to 3 decimal places, is ______

Official answer: 0.019 to 0.021