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1

Area of a base of a spherical cap of a height $h$ is $S = \pi (2Rh - h^2)$. This is the value water surface decreases as the ball dives in. This means that according to the principle of virtual work the force water sucks the ball in is $$ F_{suck} = \frac{d}{dh} \sigma S = 2 \pi \sigma (R - h), $$ where $R = 2$ cm is a ball's radius, $h \approx 1$ cm -- ...


4

It's definitely related to a surface tension That is correct. Surface tension means that the total surface area wants to be minimised. Although the water surfaces aren't very well drawn, the surface is slightly concave in the half filled glass, slightly convex in the brim filled glass. The presence of the ball reduces the total surface area. As a ...


0

If the water-air system is a closed system, when surface tension reshapes the interface shape between water and air, entropy of air increases due to increasing in volume and entropy of water decreases due to decreasing in volume. The heat to make this happen will reduce the air temperature. The water pressure will increases and air pressure will decreases. ...



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