Question

A square plate of 0.1 metre 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 newton and the coefficient of viscosity is 0.01 poise,distance between the plates in metre is:

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

Answer 1

The correct option is D 0.0005

$F=\eta A\frac{dv}{dx};A=0.1\times 0.1$
$\eta =0.01$poise
$=0.001$decapoise
$0.002=0.001\times 0.1\times 0.1\times \frac{0.1}{dx}$
$\Rightarrow dx=\frac{0.001}{2}=0.0005$