A square plate of 0.1 m side moves parallel to a second plate with a velocity of `0.1 m//s`, both plates being immersed in water. If the viscous force is 0.002 N and the coefficient of viscosity is 0.01 poise , distance between the plates in m is

Options

A. 0.1
B. 0.05
C. 0.005
D. 0.0005

Answer

D

Explanation

`F=eta A(dv)/(dx)` (drag force or viscous force)
`dx=(eta A dv)/(F)=(0.001xx0.01xx0.1)/(0.002) = 0.0005 m`. [As 0.01 Poise = 0.001 decapoise (SI unit) `A = (0.1)^2 = 0.01 m^2`.]