A | angstrom | a unit of length most often used in reference to the
wavelength of light. =10^-10 m |

atm | standard atmosphere |
a unit of pressure based on a standardized sea level terrestrial atmospheric pressure = 14.7 psi = 760 mm Hg = 1.0132 bars = 101.325 kPa |

AU | astronomical unit | a unit of length
used in astronomy and astronautics,referenced to the mean distance between Earth and Sun = 149,600,000 km = 92,961,000 mi |

C | coulomb | a unit of
electrical charge equal to the amount of electricity transferred by a current of 1 ampere for 1 second |

cal | calorie | a unit of energy
equal to the amount necessary to raise 1 g of water 1 degree C = 4.1868 J |

Cal | large calorie |
a unit of energy used in reference to the energy content of food
= 1000 cal |

eV | electron volt | a unit of energy used in particle physics, the amount of energy acquired by an electron in being accelerated through a potential difference of 1 volt = 1.60219 X 10^-19 J |

g | "gee" | the acceleration of
gravity at the mean surface of the Earth = 980.665 cm/s^2 = 32.174 ft/s^2 |

g | gram | a unit of weight in
the metric system = 0.03527 oz (avoirdupois) |

ha | hectare | a metric unit of area
used in field measurements = 100 m X 100 m, i.e.,10^4 m^2 = 2.471 acres |

Hz | hertz | a unit of frequency = cycle/s |

J | joule | unit of energy or work; the work done when the point of application of 1 newton moves a distance of 1 meter in the direction of the force = 10^7 ergs = 23.02 ft poundals |

m | meter | metric unit of length = 3.2808 ft |

mil | mil | a unit of cost |

N | newton | unit of force in the meter-kilogram-second system; that force which gives to a mass of 1 kilogram an acceleration of 1 m/s^2 = 10^5 dynes = 7.015 poundals |

Pa | pascal | a unit of pressure = 1 N/m^2 = 10^-5 bar = 0.0000098 atm = 0.0001372 psi |

rad | rad | a unit of absorbed radiation dosage = 10^-2 J/kg = 100 ergs/g |

R | roentgen | a unit of absorbed radiation based on the amount of ionization produced in tissue = 2.58 X 10^-4 coulombs/kg (defined strictly as the amount of gamma radiation sufficient to produce ions carrying one electrostatic unit of charge in one cubic centimeter of air; but loosely used to apply to any ionizing radiation producing the same effect) |

rem | rem | the roentgen equivalent, man; expresses the relative biological effect of different types of radiation For X-rays, 1 rem results from the exposure of 1 roentgen. |

t | tonne | used as a metric unit of mass for large masses = 1000 kg = 0.98 tons (long) = 1.10 tons (short) |

T | tesla | a unit of magnetic flux density = 1 Wb/m^2 |

W | watt | unit of power = 1 J/s = 10^7 ergs/s = 23.02 ft poundal/s = 1.301 X 10^-3 horse power |

Wb | weber | unit of magnetic flux; the flux which produces an electromotive force of one volt in a circuit of one turn when this flux is reduced to zero at a uniform rate in one second. |

Prefix | Name | Multiplication
factor | Example |
---|---|---|---|

G | giga | billion (10^9) | GW = gigawatt GW = 1 billion watts |

M | mega | million (10^6) | MeV = million electron volts |

k | kilo | thousand (10^3) | km = kilometer (0.6214 miles) km = 1000 meters |

c | centi | hundredth (10^-2) | cm = centimeter (2.54inches) |

m | milli | thousandth (10^-3) | mm = millimeter |

micro | millionth (10^-6) | =
micrometer = one millionth of a meter |