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

$A=(0.1{)}^2=0.01m^2$, $\eta =0.01$ Poise = 0.001 decapoise (M.K.S. unit),

$dv=0.1m/s$ and F = 0.002 N

$F=\eta A\frac{dv}{dx}$ $\therefore dx=\frac{\eta Adv}{F}=\frac{0.001\times 0.01\times 0.1}{0.002}=0.0005m$