(a) Show that for Poiseuille flow in a tube of radius R the magnitude of the wall sh...

(a) Show that for Poiseuille flow in a tube of radius R the magnitude of the wall shearing stress, , can be obtained from the relationship

for a Newtonian fluid of viscosity μ. The volume rate of flow is Q. (b) Determine the magnitude of the wall shearing stress for a fluid having a viscosity of 0.003 N·s/m² flowing with an average velocity of 100 mm/s in a 2-mm-diameter tube.