1. The problem statement, all variables and given/known data Attached. I am working on part (i). What is the resistive force? Shear stress= μ*(du/dy) = μU/l = F/A Since the force is up and down, it causes a shear stress, thus area is parallel to the force and thus it is the 4 faces B*L Thus, A=4*B*L → F=μ*U*A/l = 4*μ*U*L*B/l Where = viscosity l=clearance gap L=length of block F=Resistive force A=Area I'm not sure if that is the correct method. Can someone please verify?