Buoyancy Buoyancy is the result of gravity pulling on both the object and the water. Gravity pulls more strongly on more dense objects because they have more mass. When an object is pulled down into a fluid by gravity, it necessarily pushes water up. In this way, buoyancy can be thought of in the same way as a seesaw. The heavier object will be forced down, and will force the other up. Buoyant force can be summarized with the equation F= ρgV, where ρ is the density of the fluid, g is acceleration due to gravity, and V is the volume of the object. Buoyancy can also be approached from a potential energy perspective. When the object and an equal volume of water are lifted the same height and under the same acceleration, the more dense one will have a higher potential energy as per the equation U = mgh. (The water does not necessarily need to be lifted the same height as the object because the volume of the water is determined not only by the height raised but also by the area of the surface of water that is raised.) The lighter one will therefore be pushed up, as this is the lowest energy state possible for the system. It will therefore attempt to reach this energy state, and changing it require the input of more energy. All objects experience buoyant forces, even those that are more dense than the fluid they are in. Objects are always lifted upwards with a force equal to the volume of fluid displaced by the object. This is why it is easier to lift rocks underwater. If the object i more dense than water, it's weight is therefore greater than the water, and more than the buoyant force, which causes it to sink. This does not mean that the buoyant force is gone, but rather that the force of gravity is stronger. This is consistent with the seesaw analogy, because while a heavier mass is brought down on a seesaw, the weight of the lighter mass still pushes upwards on it, and effectively decreases its weight.