#### Problem 27E

27. Refer to the law of laminar flow given in Example 7 . Consider a blood vessel with radius $0.01 \mathrm{~cm}$, length $3 \mathrm{~cm}$, pressure difference 3000 dynes $/ \mathrm{cm}^{2}$, and viscosity $\eta=0.027$

(a) Find the velocity of the blood along the centerline $r=0$, at radius $r=0.005 \mathrm{~cm}$, and at the wall $r=R=0.01 \mathrm{~cm}$

(b) Find the velocity gradient at $r=0, r=0.005$, and $r=0.01$.

(c) Where is the velocity the greatest? Where is the velocity changing most?