Two glass plates of area $10^{-2} \mathrm{~m}^2$ have $10 \mathrm{~cm}$ thick water film between them. The surface tension of water is $70 imes 10^{-3} \mathrm{~N} / \mathrm{m}$. The force required to separate two glass plates from each other is

Question

Two glass plates of area $10^{-2} \mathrm{~m}^2$ have $10 \mathrm{~cm}$ thick water film between them. The surface tension of water is $70 	imes 10^{-3} \mathrm{~N} / \mathrm{m}$. The force required to separate two glass plates from each other is

Aicharya · Accepted Answer

Consider complete wetting. The Laplace pressure jump is given by: $\begin{aligned} & \Delta P=\frac{\sigma}{\left(\frac{h}{2}ight)}=\frac{F}{A} \ & \Rightarrow F=\frac{A \sigma}{\frac{h}{2}}=\frac{10^{-2} 	imes 70 	imes 10^{-3}}{5 	imes 10^{-2}} N=28 \mathrm{~N} \end{aligned}$

Two glass plates of area $10^{-2} \mathrm{~m}^2$ have $10 \mathrm{~cm}$ thick water film between them. The…

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