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## Homework Statement

A capillary tube of radius r = 0.3mm is filled with water. A water droplet is hanging on the bottom of the tube, as shown in the picture. The water level is h = 5.2cm. Estimate the radius of curvature of the droplet R. The coefficient of surface tension of water is σ = 7*10

^{-2}N/m.

## Homework Equations

[itex]F = \delta L[/itex]

[itex]p = \frac{F}{S} = \rho gh[/itex]

## The Attempt at a Solution

If i understand correctly, the surface tension will be [itex] F = \delta L = \delta \frac{2\pi R}{2}=\delta\pi R[/itex]. Now I'm not sure what does the tension has to be equal to? I assumed it might be the force of the pressure of liquid: [itex]F=p*S=\rho ghS=\rho gh\pi r^2[/itex]. Though I'm not quite sure about this solution - I don't really get what is the surface tension equal to, in a general case?