Originally Posted by **tracker890** Dear all： Please help me to prove the shear stress fomula by using Cylindrical coordinates. (See URL. below) http://i.imgur.com/G9uJHTj.jpg Thank for any help!! Matthew |

We really need to see your work!
What is the starting point for your derivation - is it

Is "L" the Length of the pipe (m)?

Can you specify the UNITS of the various quantities?