Water Surface and Communicating Vessels

If the Earth is round, and it pulls water to its surface; why a ball does not pull water, even though both are round?

Because gravity is not caused by the shape of an object. Gravity is caused by mass. Everything with mass have gravity. The larger the mass of an object, the greater its force of gravity.

The ball has much smaller mass than the Earth, it is not even close. Correspondingly, its gravity is also much smaller.

Besides, the experiment is obviously done in Earth environment. The Earth —that has much larger mass than the container of the water— has much bigger influence on the shape of the water surface, than the container itself.

The surface of the water will form a spherical shape, with the same center as the center of the Earth. As the center of the Earth is too far away, the curvature is not perceptible. According to our calculation, in a container 10 cm wide, the bulge of the curvature is only about 0.0000002 mm.

It is a very small bulge, and impossible to perceive. Other forces —like adhesion and cohesion— will have greater influence on water in such small container.

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