Convert from barn to hide

Unit Definition (barn)
The Barn is a slightly humorous unit of area used in nuclear physics. When atoms are bombarded with smaller particles such as electrons, the electrons are scattered as if the nucleus of the atom was a tiny solid object. The barn is used to express the apparent cross-sectional area of this scattering object. One barn is equal to 1E-28 square meters. Using this unit, physicists can say that such and such a nucleus is "as big as a barn", or 10 barns, or whatever. The proper SI unit to use for these measurements is the square femtometer (fm²); one barn equals 100 fm².

Unit Definition (hide)
The hide is a very old English unit of land area, dating from perhaps the seventh century. The hide was the amount of land that could be cultivated by a single plowman and thus the amount of land necessary to support a family. Depending on local conditions, this could be as little as 60 acres or as much as 180 acres (24-72 hectares). The hide was more or less standardized as 120 acres (48.6 hectares) after the Norman conquest of 1066. The hide continued in use throughout medieval times, but it is now obsolete. The unit was also known as the carucate.