Question

Between a plate of area $100c{m}^2$ and another plate of area $100m^2$ there is a $1mm$, thick layer of water, if the coefficient of viscosity of water is $0.01poise$, then the force required to move the smaller plate with a velocity $10cm/s$ with reference to large plate is

• A. $100dyn$
• B. ${10}^{4}dyn$
• C. ${10}^{6}dyn$
• D. ${10}^{9}dyn$

Answer 1

The correct option is A $100dyn$

$\because F=\eta A\frac{dv}{dx}\Rightarrow F=0.01\times 100\times \frac{10}{0.1}=100\text{dyne}$