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The Fahrenheit scale (/ ˈ f æ r ə n h aɪ t, ˈ f ɑː r-/) is a temperature scale based on one proposed in 1724 by the European physicist Daniel Gabriel Fahrenheit (1686–1736). [1] It uses the degree Fahrenheit (symbol: °F ) as the unit.
For most applications, the difference between the two definitions is insignificant – one international foot is exactly 0.999 998 of a US survey foot, for a difference of about 1 ⁄ 8 in (3 mm) per mile – but it affects the definition of the State Plane Coordinate Systems (SPCSs), which can stretch over hundreds of miles. [14]
Units for other physical quantities are derived from this set as needed. In English Engineering Units, the pound-mass and the pound-force are distinct base units, and Newton's Second Law of Motion takes the form = where is the acceleration in ft/s 2 and g c = 32.174 lb·ft/(lbf·s 2).
In the United States and Canada, the R-value that describes the performance of thermal insulation is typically quoted in square foot degree Fahrenheit hours per British thermal unit (ft 2 ⋅°F⋅h/Btu). For one square foot of the insulation, one Btu per hour of heat flows across the insulator for each degree of temperature difference across it.
Absolute temperature is based on thermodynamic principles: using the lowest possible temperature as the zero point, and selecting a convenient incremental unit. Celsius, Kelvin, and Fahrenheit are common temperature scales. Other scales used throughout history include Rankine, Rømer, Newton, Delisle, Réaumur, Gas mark, Leiden, and Wedgwood.
During the Anglo-Saxon period, the North German foot of 13.2 inches (335 millimetres) was the nominal basis for other units of linear measurement. The foot was divided into 4 palms or 12 thumbs. A cubit was 2 feet, an elne 4 feet. The rod was 15 Anglo-Saxon feet, the furlong 10 rods.
Of particular interest was the rood which was 15 North German feet in length, the North German foot being equivalent to 335 mm (13.2 inches). [3]: 50 Craftsmen, on the other hand used a shorter Roman foot. The standard Troy pound, destroyed in a fire in 1834. Standardization of weights and measures was a recurring issue for monarchs.
This is a collection of temperature conversion formulas and comparisons among eight different temperature scales, several of which have long been obsolete.. Temperatures on scales that either do not share a numeric zero or are nonlinearly related cannot correctly be mathematically equated (related using the symbol =), and thus temperatures on different scales are more correctly described as ...