# The acted upon by an upward, or buoyant, force

The principles of buoyancy, also known as Archimedes’ Principle state that anything completely or partially submerged in a fluid (gas or liquid) at rest is acted upon by an upward, or buoyant, force the magnitude of which is equal to the weight of the fluid displaced by the object. The volume of displaced fluid is equivalent to the volume of an object fully immersed in a fluid or to that fraction of the volume below the surface for an object partially submerged in a liquid. The weight of the displaced portion of the fluid is equivalent to the magnitude of the buoyant force. The buoyant force on an object floating in a liquid or gas is also equivalent in magnitude to the weight of the floating object and is opposite in direction; the object neither rises nor sinks. Density is why some objects float in a liquid and others sink. Water has a density of 1 g/cm3.  If an object floats in water, it means that it has a density less than  1 g/cm3. If an object sinks in water, it has a density greater than  1 g/cm3. The buoyancy of an object is its tendency to float on or rise in a liquid. An object that floats in water is said to be positively buoyant, because it has a density less than the fluid it is floating in. An object that sinks is negatively buoyant, because it has a higher density than the fluid it is floating in. To determine an object’s buoyancy, the density of an object is needed. Density is defined as the mass of an object per unit volume. Density can be increased by decreasing the volume of an object. The three states of matter, solids, liquids and gases have different properties in terms of volume. Solids and liquids both have definite volumes, while gases do not. The particles of a solid are compacted and in a pattern. The particles in a liquid are compacted but are not arranged in a pattern. The particles in a gas are not compacted, and are not arranged in a pattern. Pressure is defined as the continuous physical force exerted on or against an object by something in contact with it. In the mid 1600’s Robert Boyle studied the relationship between the pressure and the volume of a gas held at a constant temperature. Boyle’s Law describes the relationship between the pressure and volume of a fixed amount of gas at a constant temperature. The law shows that the product of the pressure and volume are observed to be nearly constant. The product of pressure and volume is defined as a constant for an ideal gas. The formula is pressure*volume = constant. There are some real-world examples of Boyle’s law. For example, when opening a bottle of soda quickly, sometimes it fizzes and shoots out of the bottle. This is due to the carbonation in sodas and changes in volume and pressure inside of the bottle. The ideal gas law states that the volume (V) occupied by n moles of any gas has a pressure (P) at temperature (T) in Kelvin.