A gas fills up the space between two long coaxial cylinders of radii `R_1` and `R_2`, with `R_1 lt R
Channel: Doubtnut
Date: 2020-08-16

A gas fills up the space between two long coaxial cylinders of radii `R_1` and `R_2`, with `R_1 lt R_2`. The outer cylinder rotates with a fairly low angular velocity `omega` about the stationary inner cylinder. The moment of friction forces acting on a unit length of the inner cylinder is equal to `N_1`. Find the viscosity coefficient `eta` of the gas taking into account that the friction force acting on a unit area of the cylindrical surface of radius `r` is determined by the formule `sigma = eta r(del omega//del r)`.