Originally Posted By: Orac

I mean it begs the question in your world why the water doesn't just fall out of my bucket given we don't have centrifugal forces but lets go beyond that problem. See the water surface is now 90 degree to gravity still want it to well up and defy earth gravity????? Think about what that looks like and no thats not what we are going to see is it


Regarding the change in the experiment: The difference between solid and liquid is the flexibility of the molecules in the lattice. If the bucket was just solid, the relative positions of the atoms are not altered. The atoms at the farthest point of the bucket will have the maximum kinetic energy. But the water molecules in the bucket can attain different speeds. The water molecules close to the solid part of the bucket are naturally held by the solid lattice and the central portion of water acquires a relatively high speed. And hence the curvature of the water surface. In the former case, the solid surface has the maximum kinetic energy; in this case the top part of the bucket has the least kinetic energy. Thus, in the former, the centre of the curve has the minimum speed, whereas, in the present case, the centre has the maximum speed. Because of the flexibility of the molecules the energy acquired remains within a maximum and minimum limit, and this creates a neat mathematical curve. In the present case, the central part (minimum point) of the curve will be slightly shifted due to gravity. In this case also, the water molecules defy gravity because of the kinetic energy, and so does not fall down.

Thus, here also you need not introduce a centrifugal force; the kinetic energy, the centripetal force and the balance of forces alone are required to explain the phenomenon.