A cubical block of side a and density `rho` slides over a fixed inclined plane with constant velocity v. There is a thin film of viscon fluid of thickness t between the plane and the block. Then the coefficeint of viscosity of the film will be

Options

A. `(3rhoag t)/(5v)`
B. `(4rhoag t)/(5v)`
C. `(rhoag t)/(5v)`
D. None of these

Answer

A

Explanation

Viscon force=`mg sin theta`
`:. eta(a^2)v/t=mg sin37^(@)=3/5 mg`
`(3)/(5) (a^(3)rho)g rArr :. eta =(3 rhoa g t)/(5v)`