Useful Formulae

57 56 constants UNITS Mathematical Constants 3.14159265358979... e 2.718281828459045... 2 1.414213562373095... 1.7724538500905516... Physical Constants speed of light in a vacuum c 2.997925 x 108 m s1 permeability of a vacuum 0 4x 107 Hm1 the permittivity constant 0 8.8542 x 1012 Fm1 mass of a proton mp 1.6726 x 1027 kg mass of a neutron mn 1.6749 x 1027 kg mass of an electron me 9.1094 x 1031 kg charge on a proton or electron e 1.6022 x 1019 C speed of sound in dry air at 0 C 331.45 ms1, 1087.4 feet s1 in water at 20 1470 ms1, 4823 feet s1 universal gravitational constant G 6.6726 x 1011 Nm2kg2 gravitational acceleration on Earth g 9.80665 ms2, 32.174 feet s2 Avogadro constant NA 6.022169 x 1023 mol1 Boltzmann constant k 1.381 x 1023 J K1 Planck constant h 6.6022 x 1034 Js StefanBoltzmann constant s 5.670 x 108Wm2K4 Physical Quantity frequency force energy power pressure charge voltage capacitance resistance conductance flux density magnetic flux inductance Symbol for quantity f F W P p Q V C R G B L Name of SI unit hertz newton joule watt pascal coulomb volt faraday ohm siemens tesla weber henry Unit symbol Hz N J W Pa C V F S T Wb H Immediate definition s1 kgms2 Nm Js1 Nm2 As JC1 C V1 V A1 1 NA1m1 Tm2 VA1s Basic units definition s1 kgms2 kgm2s2 kgm2s3 kgm1s2 As kgm2s3A1 A2s4kg1m2 kgm2s3A2 kg1m2s3A2 kgs2A1 kgm2s2A1 kgm2s2A2 as mass length time current T1 MLT2 ML2T2 ML2T3 ML1T2 TI ML2T3I1 M1L2T4I2 ML2T3I2 M1L2T3I2 MT2I1 ML2T2I1 ML2T2I2 Weights Measures British Standard Imperial Weights Measures 1 yard 3 feet 36 inches 1 fathom 2 yards 6 feet 1 furlong 220 yards 660 feet 1 mile 1760 yards 5280 feet 1 nautical mile 6080 feet 1 acre 4840 square yards 1 pound 16 ounces 1 stone 14 pounds 1 hundredweight 112 pounds 1 ton 2240 pounds 1 pint 4 gills 20 fluid ounces 1 gallon 277.4 cubic inches British Imperial Metric Metric British Imperial 1 inch 2.54000 cm 1 cm 0.393701 inches 1 foot 0.304800 metre 1 metre 3.280842 feet 1 mile 1.60934 kilometres 1 kilometre 0.621371 miles 1 ounce 28.3495 grammes 1 gramme 0.0352740 ounces 1 pound 0.45359237 kilogram 1 kilogram 2.204622 pounds 1 long ton 1016.047 kg 1 tonne 0.9842064 long tons 1 gallon 4.549631 litres 1 litre 0.219975 gallons 1 bushel 36.397 litres 1 litre 0.027475 bushels 1 acre 0.404687 hectares 1 hectare 2.47105 acres 1 cubic inch 16.3871 cubic cm 1 cubic cm 0.0610237 cubic inches fahrenheit celsius 32 celsius fahrenheit 32 1 horsepower 0.7457 kilowatts 1 kilowatt 1.3410 horsepower 1 pound per sq.inch 0.0688 atm 1 atmosphere 14.696 lbssq.inch 1 foot pound 1.355 joules 1 joule 0.738 foot pounds US Weights Measures differing from UK 1 US hundredweight 100 pounds 1 US short ton 2000 pounds 1 US short ton 0.892857 UK long tons 1 US short ton 907.184 kilogram 1 US gallon 3.785412 litres 1 litre 0.264172 US gallons 1 US gallon 0.83267 UK gallons 1 UK gallon 1.20095 US gallons 1 dry gallon 4.404884 litres 1 litre 0.227021 dry gallons 1 US bushel 35.2391 litres 1 litre 0.028378 US bushels 1 US bushel 0.9689 UK bushels 1 UK bushel 1.0321 U.S.bushels General Metric kelvin celsius 273.15 1 joule 0.2389 calories 1 bar 105 newtons per square metre 1 atmosphere 101325 Nm2 Prefixes 103 kilo, 106 mega, 109 giga, 1012 tera, 1015 peta, 1018 exa, 103 milli, 106 micro, 109 nano, 1012 pico, 1015 femto, 1018 atto.