1. The problem statement, all variables and given/known data http://scienceofdoom.files.wordpress.com/2010/12/convection-basics-1b.png How do I find the total force on that surface of the plate? 2. Relevant equations T = μ * u'(y) where T is the shear stress, μ is a scalar constant - the viscosity and u'(y) is the velocity gradient in the perpendicular direction Force = T * A 3. The attempt at a solution Does every point along the plate have a different u(y) distribution so that the shear stress at the surface, μ * u'(y=0) , is different for all of these points? And so the total force is the sum of μ * u'(y=0) * A for all of those points?