A township can have different meanings depending on the country and context in which it is used:
United States and Canada (North America): In North America, a township is a specific type of administrative division used in land survey systems. In the United States, townships are most commonly used in the Midwest and some other parts of the country. In Canada, townships are used primarily in the eastern provinces. These townships are typically a square area of land, typically six miles by six miles (36 square miles), or a similar configuration depending on the specific survey system used. Townships can be further divided into smaller units, such as sections, for land management and ownership purposes.
South Africa: In South Africa, a township refers to a residential area established during the apartheid era for non-white citizens. These areas were segregated from the main cities and towns and often experienced poor living conditions. Today, many townships have evolved and have improved living conditions, but the term is still associated with historically segregated communities.
Australia: In Australia, the term "township" is often used to refer to small rural towns or settlements. These are typically smaller than cities or larger towns and often serve as centers for local communities.
In physics, particularly in the field of nuclear and particle physics, a "barn" is a unit of area used to describe the likelihood of nuclear reactions or scattering events. The name "barn" comes from the idea that it's a very large target area, as if hitting the broad side of a barn were an easy task.
The barn is not part of the International System of Units (SI), but it's a widely recognized unit in nuclear physics. One barn is equal to 1 square femtometer (fm²), which is an incredibly small area. Specifically:
1 barn (b) = 1 square femtometer (fm²) = 10^(-28) square meters (m²)
To put it in perspective, a barn is used to describe the effective target area for nuclear reactions. Nuclear cross-sections, which describe the likelihood of nuclear interactions occurring, are often measured in barns. It's a unit that allows scientists to quantify the probability of certain atomic and subatomic processes taking place.