Units, Conversions
Basic Units and derived units time, seconds, s length, meter, m mass, kilogram, kg electric current, ampere, A temperature, kelvins, K amount, mole, mol luminous intensity, candela, cd Energy, joule, J = kg•m²/s² Charge, coulomb, C = As Capacitance, farad, F = s⁴A²/kg•m² Force, newton, N = kg•m/s² Pressure, pascal, Pa = kg/m•s² Inductance, henry, H = kg•m²/s²A² Mass/Weight US short ton = 2000 lb = 907.2 kg US long ton = 2240 lb = 1016 kg (aka Imperial ton) metric ton = 1000 kg = 2205 lb electron mass = 9.109e-31 kilograms 1 avoirdupois ounce = 28.3 g 1 troy ounce = 31.1 g one grain = 1/480 troy ounce = 64.79891 mg 1 GeV/c² = 1.783×10^−27 kg ! amu = 1 Da = 1.660e−27 kg Power/Energy A ton of TNT = 4.184 GJ = 4.184e9 J A megaton of TNT = 4.184 PJ = 4e15 J one ton HVAC capacity = 12,000 BTU/hour = 3517 watts assuming a COP of 3, that means AC power needed is 1200 W or an EER or 12, which is BTU/h / AC input 1 HP = 746 watts = 550 ft-lb/sec = 33,000 ft-lb/min = 2547 BTU/h 1 BTU per hour = 0.293 watts 1 eV = 1.6022×10^−19 J 1 GeV = 1.6022×10^−10 J BTU is defined as heat required to raise the temperature of one 1 pound of liquid water by 1°F at a constant pressure of one atmosphere. BTU/h is the power needed to raise the temperature of one 1 pound of liquid water by 1 °F at a constant pressure of one atmosphere in one hour. tons of refrigeration: It is the amount of power needed to melt one short ton of ice (2000 lb) in 24 hours foot-pounds per second is the amount of power to raise one pound against gravity by one foot in one second. 1 therm = 100,000 BTU = 105.5 MJ or 29.3 kW•hour Gasoline contains about 35 MJ/L (132 MJ/US gal). In physics, energy (Ancient Greek: ἐνέργεια energeia "activity, operation") is an indirectly observed quantity that is often understood as the ability of a physical system to do work on other physical systems. Since work is defined as a force acting through a distance (a length of space), energy is always equivalent to the ability to exert pulls or pushes against the basic forces of nature, along a path of a certain length. Time 1 time constant is 0.37 6 time constants is 0.0026 Seconds per Julian year, 3600 x 24 x 365.25 = 31,557,600 sec Gregorian year is 365.2425 days or 31,556,952 sec Sidereal year is 365.256363004 days or 31,558,149.8 sec Pressure 1 Pa = 1 N/m² 1 torr = 1/760 of a standard atmosphere 1 standard atmosphere = 101.325 kPa = 1.01325 bar = 14.7 PSI = 10.33 meters of water = 29.92 inch of mercury 1 bar = 100 kPa = 14.5 PSI 1 torr = 0.001316 atm 1 torr = 1 mm Hg (slightly off) 760 torr = 1 atm 1 PSI (lb/in²) = 6,894.8 Pa (N/m²) = 6.895x10^-3 N/mm² = 6.895x10^-2 bar Vacuum, 100 micron = 13 Pa = 0.1 mm Hg Length Ångström (symbol Å) = 0.1 nm or 1e−10 metres The parsec (parallax of one arcsecond) = 31e12 kilometres or 19.2e12 miles or 206e3 AU or 3.26 light-years. 1 US inch = 25.4 mm 1 foot = 12 inch = 305 mm 1 yard = 36 inch = 914 mm 1 mile = 5280 ft = 1609 m 1 nautical mile = 1,852 m 1 light-year = 9460730472580800 metres (exactly) ≈ 5.878625 trillion miles ≈ 63241.077 astronomical units ≈ 0.306601 parsecs Area The hectare is a unit of area defined as 10,000 square metres. or 2.471 acre 640 acres = 1 square mile 1 acre = 43,560 square feet = 4,050 square meters Volume US dry gallon = 4.405 L Imperial (UK) gallon = 4.546 L 1 UK fluid ounce = 28.4 ml = 1.733 in³ 1 US fluid ounce = 29.6 mL = 2 tablespoons = 6 teaspoons = 1.805 cubic inch = 1.041 avoirdupois ounce of water = 1.041 imperial (UK) fluid ounces 1 US gill = 4 US fluid ounce 1 US cup = 8 US fluid ounce 1 US pint = 16 US fluid ounce 1 US quart = 32 US fluid ounce 1 US gallon = 128 US fluid ounce = 3.785 L = 3785 cm³ 1 Liter = 33.8 US fluid ounce 1 m³ = 1000 L = 264 US gallon = 35.3 cubic feet = 1.307 cubic yard 1 acre-ft = 325800 US gal = 1233.5 m³ 100000 L = 100 m³ 10000 L = 10 m³ 1000 L = 1 m³ 100 L = 0.1 m³ 10 L = 10 dm³ = 10000 cm³ = 0.01 m³ 1 L = 1 dm³ = 1000 mL = 1000 cm³ = 0.001 m³ 0.1 L = 0.1 dm³ = 100 mL = 100 cm³ = 0.0001 m³ 0.01 L = 10 mL = 10 cm³ = 0.00001 m³ 0.001 L = 1 mL = 1 cm³ = 0.000001 m³ 1 mL = 1000µL = 1000 mm³ = 1 cm³ = 0.000001 m³ 0.1 mL = 100µL = 100 mm³ = 0.1 cm³ 0.01 mL = 10µL = 10 mm³ = 0.01 cm³ 0.001 mL = 1µL = 1 mm³ = 0.001 cm³ 1 µL = 1000 nL = 1 mm³ = 100000 µm³ 0.1 µL = 100 nL = 0.1 mm³ = 10000 µm³ 0.01 µL = 10 nL = 0.01 mm³ = 1000 µm³ 0.001 µL = 1 nL = 0.001 mm³ = 100 µm³ Temperature C = (5/9)(F–32) C = K − 273.15 K = (5/9)(F + 459.67) K = C + 273.15 F = (9/5)C + 32 F = (9/5)K − 459.67 F = R – 459.67 R = F + 459.67 For temperature intervals rather than specific temperatures, 1 °F = 1°R = (9/5)°C = (9/5)K 1 °C = 1 K = (5/9)°F = (5/9)°R deciBell dB = 10 log P or 20 log V Power ratio = 10^(dB/10) Voltage ratio = 10^(dB/20) . . . . .power . . voltage 0.1 dB . 1.02 .. 1.01 0.2 dB . 1.05 .. 1.02 0.5 dB . 1.12 .. 1.05 1 dB .... 1.26 .. 1.12 2 dB .... 1.54 .. 1.26 3 dB .... 2.0 .... 1.41 4 dB .... 2.51 .. 1.58 6 dB .... 4.0 .... 2.0 8 dB .... 6.31 .. 2.51 10 dB . 10 ...... 3.16 20 dB . 100 .... 10 30 dB . 1000 .. 31.6 40 dB . 10k . . 100 50 dB . 100k .. 316 60 dB . 1M .... 1000 70 dB . 10M .. 3160 80 dB . 100M . 10k etc. dB references Voltage dBu or dBv, reference is 0.775 VRMS dBV, reference is 1 volt RMS dBmV, reference is 1 mV across 75 ohms dBµV or dBuV, reference is 1µV Acoustic Power dB(SPL) (Sould Pressure Level), reference to 20 µPa dB(PA), reference to 1 Pz dB SIL (Sound Intensity Level), reference to 10^-12 W/m² dB SWL (sound Power Level) referenced to 10^-12 W dB(A), dB(B), dB(C). these are dB SIL but with different frequency weighing filters. dB HL (Hearing Level) is used in audiograms as a measure of hearing loss Electrical Poewr dBm is db referenced to 1 mW dBW is db referenced to 1 watt they differ by a factor of 1000 or 30 dB dBFS (Full Scale) reference is the max signal the amplifier can handle dBTP (True peak) reference is the max peak signal the amplifier can handle Electron 1 C = 6.242e18 electrons charge on electron 1.602e−19 C electron mass = 9.10938188e-31 kilograms Denier Denier is a unit of measure for the linear mass density of fibers. It is defined as the mass in grams per 9,000 meters. 8 dernier = 8 g/9000 meter The conversion formula is d = √(dernier•1.415e-6 / ρ) where d is diameter in cm ρ is material density in g/cm³ R-Value The conversion between SI and US units of R-value is 1 h·ft²·°F/Btu = 0.176110 K·m²/W, or 1 K·m²/W = 5.678263 h·ft²·°F/Btu. SI (metric) prefixes da (deca) = x10 (rarely used) h (hecto) = x100 (rarely used) k (kilo) = x1000 = e3 M (mega) = x1000000 = e6 G (giga) = x1000000000 = e9 T (tera) = x1000000000000 = e12 P (peta) = x1000000000000000 = e15 E (exa) = x1000000000000000000 = e18 Z (zetta) = x1000000000000000000000 = e21 Y (yotta) = x1000000000000000000000000 = e24 d (deci) = /10 = e-1 (rarely used) c (cent) = /100 = e-2 (rarely used except for cm) m (milli) = /1000 = e-3 µ (micro) = /1000000 = e-6 n (nano) = /1000000000 = e-9 p (pico) = /1000000000000 = e-12 f (femto) = /1000000000000000 = e-15 a (atto) = /1000000000000000000 = e-18 a (zepto) = /1000000000000000000000 = e-21 a (yocto) = /1000000000000000000000000 = e-24 SI binary prefixes Ki (kibi) = x1024 Mi (mebi) = x1024² Gi (gibi) = x1024³ Ti (tebi) = x1024⁴ Pi (pebi) = x1024⁵ Ei (exbi) = x1024⁶ Zi (zebi) = x1024⁷ Yi (yobi) = x1024⁸ |
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