What is buoyancy?
Buoyancy is the ability of an object to float in a liquid, such as water. This concept helps to explain why some things float while other objects sink. Buoyancy is an important factor in the design of many objects and in a number of water-based activities, such as boating or scuba diving. The mathematician Archimedes discovered much of how buoyancy works almost 2000 years ago. In his research, Archimedes discovered that an object is buoyed up by a force equal to the weight of the water displaced by the object. In other words, a inflatable boat that displaces 100 pounds (45 kilograms) of water is buoyed up by that same weight of support. An object that floats in the water is known as being positively buoyant. An object that sinks to the bottom is negatively buoyant, while an object that hovers at the same level in the water is neutrally-buoyant. This same idea helps to determine what will float in water and what will sink. If an object weighs more than the weight of the water it displac
Different factors contribute to how high — or low — in the water you float. First, your body type has a lot to do with your buoyancy. Fat floats, as you’ve probably heard, while your bones and muscles, denser than fat, are not as willing to float. Also, the relative size of your lungs to the rest of your body determines how high in the water your body will float. Second, the density of the water is a factor. Saltier water weighs more per unit of volume, so you will float higher in saltier water (the Red Sea, for instance) than you would in fresh water. Finally, there is a curious phenomenon of apparently greater buoyancy — for some people — in deep water. According to Melon Dash of the Transpersonal Swimming Institute, “Buoyancy and feeling buoyancy are two different things. You can be buoyant but not feel buoyant. Your buoyancy does not change between the shallow and the deep. Your feeling of buoyancy may change. “Feeling buoyancy in water is all about ‘presence’ in one’s body. Presen
Buoyancy refers to the tendency of objects immersed in water to float or sink. Objects that are positively buoyant float on top of water; objects that are negatively buoyant sink; and objects that are neutrally buoyant neither float nor sink, but stay where you place them (Figure 6). This principle was first stated by Archimedes (Greek mathematician and engineer, lived about 287 B.C. to 212 B.C.). He observed that an object immersed in water sinks or floats depending on the weight of water it displaces. If the weight of water displaced is less than the object’s weight, it sinks; if the displaced water weighs more, the object floats; and if the displaced water is the same the object is neutrally buoyant.
