The equation I got for part A is V z =-1/[4(u o (1-e -t/B ))]*(dP/dz)*(R 2 -r 2 ) from Navier-Stokes in the z-dir and substituting the viscosity...

The equation I got for part A is Vz=-1/[4(uo(1-e-t/B))]*(dP/dz)*(R2-r2) from Navier-Stokes in the z-dir and substituting the viscosity equation. I'm not exactly sure what parts i,ii, and iii are asking for though. I think Vmax occurs in the middle of the tube where dV/dz is zero but I'm not sure what the position equation would be or the "spatial variable".