Buoyancy. Buoyancy is the tendency of an object to float in a fluid, such as air or water. The principle of buoyancy was first discovered by Greek mathematician Archimedes (c. 287 â 212 b.c.) and is therefore often called Archimedes' Principle.therwise, it floats. The formal statement of Archimedes' Principle is this: the buoyant force acting on an object placed in a fluid is equal to the weight of the fluid displaced by the object. Suppose that the wood block in the example above has a volume of 1 cubic foot. A cubic foot of water weighs about 62.4 pounds.
Epidemic: The occurrence of more cases of a disease than would be expected in a community or region during a given time period.A sudden severe outbreak of a disease such as SARS. From the Greek epi-, upon + demos, people or population = epidemos = upon the population.. See also: Endemic; Pandemic.pidemic: The occurrence of more cases of a disease than would be expected in a community or region during a given time period.
Endemic diseases are often confused with epidemics. However, an epidemic refers to an outbreak of a disease. An epidemic occurs when a disease is spreading through one or more populations. In contrast, an endemic disease is one that is constantly present in a group or geographic area. Pandemics are world wide epidemics. Under certain circumstances, an epidemic can lead to a disease becoming endemic. Endemic diseases are not always present at high levels.