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Let's imagine a sphere touching a plane. Then, I may consider valid the law for adhesion coming from VDW forces:

[tex]F=\frac{Aa}{6h^2}[/tex]

where A is the Hammaker constant, a is the sphere radius and h is the gap between the two bodies. My question is, is there a way of calculating the equilibrium distance [tex]h_o[/tex] where the force reaches its maximum? What cannot be is that as h tends to zero F tends to infinity. There must be some point of equilibrium for very small h in which maybe repulsion forces start to take place. Is that right?

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# Calculating the equilibrium distance

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