Please help in this problem

I don’t understand how to solve this. Please explain.

Note I think we are free to assume variables required in the final answer.

I think, that if the surface tension of liquid were infinitesimal , then water would continue to expand radially. But it is impossible because everything is finite and it is necessary to find such parameters of thickness and radius of water that give shows the moment when surface tension force would be equal to arbitarry radial force. Maybe this forse we can find from bernoulli equation:

f=\rho u^2h

f is force per unit length (radius)
h is the thickness of water.

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Hmm yeah… Let me solve this way

Now we’ll have to find the relation for h so that we can introduce r

what is your expression for curvature force f coming out? I am getting 2\sigma per unit length…

That’s right, I found this expression too.
So I thought a litts bit and because of lack of known values, I think we can use the dencity and the surface tension of water. Also we can write an equation for flux of water from Gauss theorem, but I am not sure. This equation may be useful.

Ф=\int(\vec{u}\vec{dS})=u(2\pi rh)
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yeah we can write flux and then use the relation in h

ok yeah i got the answer I think…