Question

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

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

Answer 1

The correct option is D 0.0005

$A={\left(0.1\right)}^2=0.01m^2,\eta =0.01poise=0.001decapoise(M.K.S.unit),dv=0.1m/sandF=0.002NF=\eta A\frac{dv}{dx}\therefore dx=\frac{nAdv}{F}=\frac{0.001\times 0.01\times 0.1}{0.002}=0.0005m.\therefore h=\frac{4900}{1960}=2.5cm.$