So the negligible mass is important because the force of static friction = uFn, and Fn = mass of boundary layer * g. So because there is small amount of mass, there is a small normal force and a small amount of static friction keeping it from slipping, Is that right?
Thank you. Okay so maybe I'm not understanding friction correctly. The friction force that is allowing the fluid underneath the boundary layer to slide with the boundary layer, is that static friction? I'm sorry if that's dumb I am teaching myself physics.
https://openstax.org/books/university-physics-volume-1/pages/14-7-viscosity-and-turbulence
I am trying to understand the derivation from Figure 14.36 which starts with " The fluid to be measured is placed between two parallel plates. The bottom plate is held fixed, while the top plate is moved...