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kilowatt-hour or megajoule

Discussion in 'Electronic Basics' started by Tim923, Oct 17, 2004.

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  1. Tim923

    Tim923 Guest

  2. Don Kelly

    Don Kelly Guest

    No- It is just that historically power is measured in watts and still is.
    Hence the use of kWh was adopted for energy. This predated the use of the
    "Joule" as a standard energy measure and industry has stuck with it.

    In many places the horsepower is not used - kW is used instead. Joules are
    used for heat energy but the US still uses Therms. Be thankful you are not
    using a stone-furlong -fortnight set of units.

    Don Kelly

    remove the urine to answer

    is valid.
     
  3. Rich Grise

    Rich Grise Guest

    I read recently that some city specified wheelchair ramps in centimeters
    rise per foot horizontal.

    Cheers!
    Rich
     
  4. John G

    John G Guest

    I do not know about the US but in Australia car tyres have the rim
    diameter in inches and the tread width in millimetres.
    This is a multicultural nation!!
     
  5. JeffM

    JeffM Guest

    some city specified wheelchair ramps in centimeters rise per foot horizontal
    We call them tires, but yeah, same here.
    How about eye tests? 20/20 vision == 20mm characters readable @ 20 feet.
     
  6. Is it more direct to measure yards than meters? Or more direct
    to measure pounds than kilograms? Answer: no.


    Also: (heh) is quantity of electricity measured in coulombs... or joules?


    And just how large is a coulomb, in millimeters? About 0.4mm!

    For mobile electrons in copper wires, there are around 8.5e22 electrons
    per cm^3, and 1.6e-19 coulombs per electron, gives 13600 coulombs per cc,
    so each coulomb is about 0.04cm across!

    http://amasci.com/miscon/speed.html
     
  7. tlbs101

    tlbs101 Guest

    I always wondered why they couldn't have set a Coulomb equal to a Mole
    of charge. Either that or create a new electrical unit of charge
    equal to a Mole of charge -- how about the Heavi (for Heaviside).
     
  8. Rich Grise

    Rich Grise Guest

    Well, no, actually, that means that at 20 feet, you can resolve what
    "normal" eyes can resolve at 20 feet. 20/200 means that at 20 feet,
    the letters have to be so big for you to resolve them, that they're
    the size that normal eyes can resolve from 200 feet, and so on.

    At least, that's what they taught me, back when schools actually
    taught stuff. ;-)

    Cheers!
    Rich
     
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