Question

A drop of water of mass m and density ρ is placed between two well cleaned glass plates the distance between which is d. What is the force of attraction between the plates? T= surface tension

• A.
• B.
• C.
• D.

Answer 1

The correct option is C

For cylindrical surface $△P=\frac{T}{r}not\frac{2T}{r}$
$Herer=\frac{d}{2}$
$△P=\frac{2T}{d}$
$\therefore P_2-P_1=\frac{2T}{d}=△P$
$\therefore F=\left(△P\right)S=\left(△P\right)\left(\frac{V}{d}\right)=\frac{\left(△P\right)m}{\rho d}$
$OrF=\frac{2Tm}{\rho d^2}$