UNITS AND CONVERSION FACTORS

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
= 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.

METRIC PREFIXES USED

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