A 40 mm diameter 2m long straight uniform pipe carries a steady flow of water (viscosity 1 .02 centipoises) at the rate of 3.0 liters per minute. What is the approximate value of the shear stress on the internal wall of the pipe?
a. 0.0166 dyne/cm2
b. 0.0812 dyne/cm2
c. 8.12 dyne/cm2
d. 0.9932 dyne/cm2