log law for wind velocity profile

Tom P

Can someone help please, I'm confused...

I'm trying to create a simple spreadsheet to give wind speeds at a range of heights, from one input wind speed at a reference height.

I want to do it using the log law, where u is a function of friction velocity. Friction velocity is fucntion of the wall shear stress. And the wall shear stress is a function of du/dy. I don't understand how to use this du/dy? I have 1 value for flow velocity (u) at height (y). I know du/dy is not simply u/y, but don't understand what else I can do!

Would greatly appreciate any help. Thank you.