Search results
Results from the WOW.Com Content Network
The rod, perch, or pole (sometimes also lug) is a surveyor's tool [1] and unit of length of various historical definitions. In British imperial and US customary units, it is defined as 16 + 1 ⁄ 2 feet, equal to exactly 1 ⁄ 320 of a mile, or 5 + 1 ⁄ 2 yards (a quarter of a surveyor's chain), and is exactly 5.0292 meters.
A light-year, alternatively spelled light year (ly or lyr [3]), is a unit of length used to express astronomical distances and is equal to exactly 9 460 730 472 580.8 km, which is approximately 9.46 trillion km or 5.88 trillion mi.
The speed of light could then be expressed exactly as c 0 = 299 792 458 m/s, a standard also adopted by the IERS numerical standards. [19] From this definition and the 2009 IAU standard, the time for light to traverse an astronomical unit is found to be τ A = 499.004 783 8061 ± 0.000 000 01 s, which is
Farm-derived units of measurement: The rod is a historical unit of length equal to 5 + 1 ⁄ 2 yards. It may have originated from the typical length of a mediaeval ox-goad. There are 4 rods in one chain. The furlong (meaning furrow length) was the distance a team of oxen could plough without resting. This was standardised to be exactly 40 rods ...
Rood is an English unit of area equal to one quarter of an acre [2] or 10,890 square feet, exactly 1,011.7141056 m 2. A rectangle that is one furlong (i.e., 10 chains, or 40 rods) in length and one rod in width is one rood in area, as is any space comprising 40 perches (a perch being one square rod).
Secondary units (multiples and submultiples) are derived from these base and derived units by multiplying by powers of ten. For example, where the unit of length is the metre; a distance of 1 metre is 1,000 millimetres, or 0.001 kilometres.
Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!
The chain (abbreviated ch) is a unit of length equal to 66 feet (22 yards), used in both the US customary and Imperial unit systems. It is subdivided into 100 links. [1] [2] There are 10 chains in a furlong, and 80 chains in one statute mile. [2] In metric terms, it is 20.1168 m long. [2]