Determine,from first principles,the viscosity?

[joey1]

guys i am doing fluid mechanics for the first time at university level
the textbook that was recommended by the lecturer is crap and the study guide only refers to the textbook
please guys need your help
with this question

3 N is needed to push a 50 mm diameter piston, 30 mm long slides in a vertical cylinder
with an inside diameter of 55 mm at a velocity of 0.5m/s. There is a film of lubricating oil between
the two cylinders.Determine, from first principles, the viscosity of the lubricating oil film.Assume
the lubricating oil is a Newtonian fluid.

thanks
jovan

 

[Unrest]

Well you're not supposed to post textbook questions here.

But 'first principles' means find out the definition of viscosity.

Should be something like the ratio between shear stress and shear strain rate. Once you know what those quantities mean, it's fairly clear from the problem how to find them.