Gravity affects all matter in the same way. Therefore, gravity will cause the fluid body to move in the direction of its net acceleration, dictated by the vector sum of the acceleration of each individual particle.
Fluid pressure can be caused by gravity, acceleration, or forces in a closed container. For the layman: anywhere that gravity is present, liquid will gravitate toward it.
Liquid molecules move rapidly and move out of the way. Gravity pushes the liquid and the fluid moves. The quantity of water that is transferred is equal to the weight of that object. If the object takes up more room than the equivalent weight of water, it floats. If the object takes up less room, it sinks.
The weight of the object is relative to its density. Gravity attracts an object sitting on top of a solid in the same way as a liquid, but the molecules in a solid do not move the way that liquid does.
