1.1 For Hagen-Poiseuille flow, show that the shear stress at the tube wall (t = t,_R) can be W r-R 4μο ||tw| = лR³ written as 1.2 For a laminar flow of a Newtonian fluid in a tube of circular cross section, a. Show that the mean velocity over the cross section is ½ of the peak velocity in the tube. b. Show that the ratio of mean shear to the wall shear rate is 2/3.