Hydrostatic equilibrium

Hydrostatic equilibrium happens when the pull of gravity is balanced by a pressure gradient which creates a pressure-gradient force in the other direction. The balance of these two forces is known as the hydrostatic balance. It flattens the surface of undisturbed liquids.

Hydrostatic Equilibrium Media

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  Diagram of a newly formed planet in a state of hydrostatic equilibrium.

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  If the highlighted volume of fluid is not accelerating, the forces on it upwards must equal the forces downwards.