question_answer

Which one of the following correctly represents the shear stress distribution across a section of a circular pipe having a viscous flow?

A) \[\tau =\frac{\partial p{{r}^{2}}}{\partial x}\]               

B) \[\tau =\frac{\partial p\left( r/2 \right)}{\partial x}\]

C) \[\tau =-\,\,\frac{\partial p\left( r/2 \right)}{\partial x}\]       

D) \[\tau =\frac{\partial p\left( r \right)}{\partial x}\]