A body floats in a liquid when the body’s weight is equal to the weight of the liquid displaced.
- The density of the body’s material is less than or equal to the density of the liquid.
- When the body floats in neutral equilibrium, the body’s weight is equal to the weight of displaced liquid.
- The centre of gravity of the body and centre of gravity of the displaced liquid should be in one vertical line.
Law of floatation
Archimedes, the Ancient Greek scientist, first stated the principle of floatation. According to him, all the objects placed in a liquid experience an upward force that allows the body to float if it displaces water with a weight equal to the body’s weight. This upward force is known as buoyant force, and the law is known as the law of buoyancy.
When a body is immersed partly or wholly in a liquid, there is an apparent loss in the body’s weight, which is equal to the weight of the liquid displaced by the body.