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[1] This diagram gives a visual analogue using a square: regardless of the size of the square, the added perimeter is the sum of the four blue arcs, a circle with the same radius as the offset. More formally, let c be the Earth's circumference, r its radius, Δc the added string length and Δr the added radius.
The US survey foot is defined so that 1 metre is exactly 39.37 inches, making the international foot of 0.3048 metres exactly two parts per million shorter. This is a difference of just over 3.2 mm, or a little more than one-eighth of an inch per mile.
Respectively, these square divisions of land are approximately 80 chains (one mile or 1.6 km), 40 chains (half a mile or 800 m), and 20 chains (a quarter mile or 400 m) on a side. The chain is still used in agriculture: measuring wheels with a circumference of 0.1 chain (diameter ≈ 2.1 ft or 64 cm) are still readily available in Canada and ...
Li or ri (Chinese: 里, lǐ, or 市里, shìlǐ), also known as the Chinese mile, [citation needed] is a traditional Chinese unit of distance. The li has varied considerably over time but was usually about one third of an English mile and now has a standardized length of a half- kilometer (500 meters or 1,640 feet or 0.311 miles ).
In radar-related subjects and in JTIDS, a data mile is a unit of distance equal to 6,000 feet (1,829 metres; 0.9875 nautical miles; 1.136 miles). An international mile is 0.88 data mile. The speed of light is 299,792,458 metres per second (983,571,056 ft/s), or about one foot per nanosecond .
When each equatorial degree was divided into 18 leagues, the geographical mile was equal to 1 / 54 degree or about 2.06 kilometres (1.28 mi); when divided into 20 leagues, the geographical mile was equal to 1 / 60 degree, approximating the values provided above; and when divided into 25 leagues, the geographical mile was equal ...
1 square yoctometre (ym 2) 1 ym 2 10 −43 100,000 ym 2: 1 femtobarn [3] 10 −42: 1 square zeptometre (zm 2) 1 zm 2 10 −36: 1 square attometre (am 2) 1 am 2 10 −30: 1 square femtometre (fm 2) 1 fm 2 10 −29 66.52 fm 2: Thomson cross-section of the electron [4] 10 −28 100 fm 2: 1 barn, roughly the cross-sectional area of a uranium ...
Earth radius (denoted as R 🜨 or R E) is the distance from the center of Earth to a point on or near its surface. Approximating the figure of Earth by an Earth spheroid (an oblate ellipsoid), the radius ranges from a maximum (equatorial radius, denoted a) of nearly 6,378 km (3,963 mi) to a minimum (polar radius, denoted b) of nearly 6,357 km (3,950 mi).