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Why are temperature/voltage/etc not measured all in KJ?

  1. Mar 11, 2005 #1
    why are temperature/voltage/etc not measured all in KJ???

    ditto.....
     
  2. jcsd
  3. Mar 11, 2005 #2

    dextercioby

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    Why???They're all other physical quantities.

    Daniel.
     
  4. Mar 11, 2005 #3

    Pengwuino

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    Yah what he said :P

    Joules is a unit of work/heat. Temperature is a state variable. Voltage is another state variable. Its like asking why isnt mass measured in Joules.
     
  5. Mar 11, 2005 #4

    dextercioby

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    It's not necessarily thermodynamics.Voltage for example is not defined in thermodynamics.

    Daniel.
     
  6. Mar 11, 2005 #5

    pervect

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    Voltage is already measured in joules/columb - energy / unit charge.

    Temperature scales were around long before thermodynamics, so they are a bit of a legacy unit. And they are conveniently sized for everyday use.
     
  7. Mar 11, 2005 #6
    i mean, why aren't the energies measured in the same unit? also, chemical energy is measured in jouldes, in food atleast...

    and i din't relise that joules were used for electricity

    PS: im only doing a single physics for my science GCSE, but next year i should hopefully be doing AS physics
     
    Last edited: Mar 11, 2005
  8. Mar 11, 2005 #7

    dextercioby

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    Energies are measured in various units.It's either erg,or Joule,or Calorie and many more.Between them there are the so-called CONVERSION RULES.Just like in the scales for temperature...

    Daniel.
     
  9. Mar 12, 2005 #8
    We are unfortunate for having so many systems of measurement. This is not the case only with energy. Consider length, or mass. We have metres, miles, feet, inches, kg, ounces, pounds, and so on.
    But just take the SI system as the official one, and you will have one basic unit for each quantity.
     
  10. Mar 12, 2005 #9

    brewnog

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    Hexhunter,

    Why don't you use miles to weigh yourself? And why don't you order a metre of milk? We have different units to quantify different types of measurement, although (as Dex pointed out) they are often related, and you can usually describe one unit (Volt, like on a battery, for example) in terms of other units.

    Good luck with your GCSE, stick at it and if you can do an AS in Physics then you'll have a better chance of getting into uni!
     
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