Question

A square plate $0.1 \,m$ side moves parallel to second plate with a velocity of $0.1 \,m \,s^{-1}$ , both plates being immersed in water. If the viscous force is $0.002\, N$ and the coefficient of viscosity $0.001$ poise, distance between the plates is

• A. $0.1\, m$
• B. $0.05\,m$
• C. $0.005 \, m$
• D. $0.0005 \, m$

Answer 1

Answer: (D)

$0.0005 \, m$

Answer 2

As $F=\eta A \frac{d v}{d x}$ or $dx=\eta \frac{Adv}{F}=\frac{0.001\times\left(0.1\right)^{2}\times0.1}{0.002}$ $=0.0005 \, m$