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Homework Help: Confused, charles law

  1. Nov 29, 2006 #1
    why is the answer different if you didnt convert T into kelvin considering that
    they have the same temp in actual process
     
  2. jcsd
  3. Nov 29, 2006 #2

    HallsofIvy

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    The same temperature? Yes, but Kelvin and Celcius use different numbers to represent that temperature! Using different numbers in a formula typically gives different answers.

    Oh, I see what you mean! Charles Law says that [itex]V_1/T_1= V_2/T_2[/itex] so [itex]V_1/V_2= T_1/T_2[/itex] and you are asking why the differences don't "cancel". They would IF Kelvin temperature were simply a multiple of Celcius Temperature. If K= aC, then [itex]K_1/K_2= (aC_1)/(aC_2)= C_1/C_2[/itex]. But they are not: Kelvin temperature is Celcius temperature minus 273.15. That is K= C-a. [itex]K_1/K_2= (C_1- a)/(C_2-a)[/itex] and we can't cancel.
     
  4. Nov 29, 2006 #3

    dextercioby

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    And keep it then in Celsius, Fahrenheit, Reaumur, Beufort, Mercali, Richter or other scales ? Maybe it's probably Charles law was valid only when both the volume and the temperature are expressed in SI units, with T the absolute thermodynamical temperature measured in Kelvin.

    Daniel.
     
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