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How many of the following 29 units have you never heard of before?  The international system of units consists of a short list of base units defined in an absolute manner that does not refer to any other units.  The base units are consistent with the part of the metric system called the MKS (meter-kilogram-second) system.

  • meter for distance
  • kilogram for mass
  • second for time
  • ampere for electric current
  • kelvin for temperature
  • mole for amount of substance
  • candela for intensity of light

Other international system units, called international system derived units, are defined algebraically in terms of these fundamental units.  For example, the international system unit of force, the newton, is defined to be the force that accelerates a mass of one kilogram at the rate of one meter per second per second.  This means the newton is equal to one kilogram meter per second squared, so the algebraic relationship is N = kg·m·s-2.  Currently there are 22 international system derived units. They include:

  • radian and steradian for plane and solid angles, respectively
  • newton for force and the pascal for pressure
  • joule for energy and the watt for power
  • degree Celsius for everyday measurement of temperature
  • electricity: the coulomb (charge), volt (potential), farad (capacitance), ohm (resistance), and siemens (conductance)
  • magnetism: the weber (flux), tesla (flux density), and henry (inductance)
  • lumen for flux of light and the lux for illuminance
  • hertz for frequency of regular events and the becquerel for rates of radioactivity and other random events
  • gray and sievert for radiation dose
  • katal, a unit of catalytic activity used in biochemistry

Five of those were completely new for me: siemens, becquerel, gray, sievert, and katal.  Did Tesla and Farad get together to design a flux capacitor? ;-)

Posted on Sunday, May 28, 2006 7:01 PM Humor and Fun , & Etc. | Back to top

Comments on this post: International Units Trivia

# re: International Units Trivia
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how do you change a unit to a mg thank you rosie
Left by rosie ehrsam on Aug 08, 2006 7:57 PM

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