Question

A drop of water of volume V is pressed between the two glass plates so as to spread to an area A. If T is the surface tension, the normal force required to separate the glass plates is

• A. $\frac{TA^{2}}{V}$
• B. $\frac{2TA^{2}}{V}$
• C. $\frac{4TA^{2}}{V}$
• D. $\frac{TA^{2}}{2V}$

Answer 1

Answer: (B)

$\frac{2TA^{2}}{V}$

Answer 2

Force required to separate the glass plates $F = \frac{2AT}{t} \times \frac{A}{A} = \frac{2TA^{2}}{(A \times t)} = \frac{2TA^{2}}{V}$.