Question

A drop of water of mass $m$ and density $\rho$ is placed between two well cleaned glass plates, the distance between which is $d$. what is the force of attraction between the plates?

• A. $\frac{Tm}{3\rho d^2}$
• B. $\frac{4Tm}{\rho d^2}$
• C. $\frac{2Tm}{\rho d^2}$
• D. $\frac{Tm}{\rho d^2}$

Answer 1

The correct option is C $\frac{2Tm}{\rho d^2}$

$f=T\times L$

Now$f=2T\times L[$ Because of 2 surfaces $]$

$f=\frac{2TLd}{d}\Rightarrow \frac{2TA}{d}$

$\rho =\frac{M}{Ad}\Rightarrow A=\frac{M}{\rho d}$

$So,f=\frac{2TM}{\rho d^2}$

Answer: $\left(C\right)\frac{2TM}{\rho d^2}$