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Homework Help: Very Hard Question

  1. Aug 15, 2006 #1
    1 Celsius= 274.15kelvin Right

    So 274.15+274.15=548.30 Kelvin(2 Celsius)

    2 Celsius Is= 273.15 Im Confused Help
  2. jcsd
  3. Aug 15, 2006 #2
    Actually 2 Celsius should be 275 Kelvin.

    The answer is very easy. Celsius's origin is at the freeizing point of water, that's 0. Anything below 0(freezing) is negative, anything above is positive. Same for Farenheut accept freezing for water is 32.

    Kelvin is different, it works at the absoloute coldest temperature possible with no heat. That's called Absolute Zero. That's about -273 Celsius . Therefore the freezing point of water on Kelvin is 273. 1 Celsius=274 and
  4. Aug 15, 2006 #3
    In addition to what Line said, the trick lies in the magnitudes of one degree Celcius and one Kelvin, which happen to be the same. The zero point is simply much lower for Kelvin (-273 deg C). So to convert any Celcius measurement to Kelvin, all you have to do is add 273 and voila, you have your answer.
  5. Aug 15, 2006 #4
    Im Still Confused Because The Ratio Isnt Right, How Come
  6. Aug 15, 2006 #5
    they are not related by a ratio, they are related by a difference of 273.

    so 2 celsius is 273+2=275
    0 celsius = 273+0=273
    -273 celsius = 273-273=0
  7. Aug 15, 2006 #6
    If you increase the temperature of an object by 1 deg C, it's EXACTLY the same as increasing it by 1 K. So, if you really want ratios, the ratio magnitudes of Celcius to Kelvin is 1:1.
  8. Aug 15, 2006 #7
    Not really - the ratio changes. mengshuen was correct in saying that they are not related by a ratio, but by a difference. I understand what you're saying, but thinking of this in terms of ratios is unnecessary confusion.

    What you're saying would be correct if you changed it to: the ratio of the magnitudes of degrees Celsius + 273 and of degrees Kelvin is 1:1.
  9. Aug 15, 2006 #8


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    It would appear that you are thinking of a function, y = m x in which K is proportional to °C, where m is a proportionality constant. This is not the case.

    Temp (K) = Temp (°C) + 273.15,
    so 0 K = -273.15 K, or 273.15 K = 0°C, or 100°C = 373.15 K.

    this is like y = ax + b, where a = 1, or y = x + b.

    the temperature 'difference' in K = temperature difference in °C.

    See - http://hyperphysics.phy-astr.gsu.edu/Hbase/thermo/temper.html#c3
  10. Aug 16, 2006 #9
    Lol, that sentence was supposed to be "the ratio OF magnitudes of Celcius to Kelvin is 1:1". That's what I get for typing so late at night.
  11. Aug 16, 2006 #10
    So You Cant Really Add Kelvins And Then Express Them In Celsius? Because Ive Done That In Our Test Cause I Relly Dont Know The Equation What I Know Is That 1 Deg C Is=274.15 Kelvin
  12. Aug 16, 2006 #11
    uhm, you can... everyone here explained it already...

    if you take measure 273.15 Kelvin, it means you measured 0 Celsius.
    if you add 25 Kelvins to that temperature you get 298.15 Kelvin = 25 Celsius!

    -273.15 Celsius = 0 Kelvin
    -272.15 Celsius = 1 Kelvin
    -271.15 Celsius = 2 Kelvin
    -1 Celsius = 272.15 Kelvin
    0 Celsius = 273.15 Kelvin
    1 Celsius = 274.15 Kelvin
    2 Celsius = 275.15 Kelvin

    so, as astronuc said:
    <Kelvin> = <Celsius> + 273.15
    <T1 in Kelvin> - <T2 in Kelvin> = <T1 in celsius> - <T2 in celsius>
  13. Aug 16, 2006 #12
    Take This As An Example You Have 274.15 Kelvin Which Is 1 Celsius
    So If You Add Another 274.15 Kelvin Which Is 1 Celsius To Another 274.15=1 Celsius Then You Will Have 2 Celsius Right Or Not Because 2 Celsius=275.15 Kelvin
  14. Aug 16, 2006 #13
    when you add temperatures you actually adding a difference:

    and <T2-T1> is the same for Celsius and for Kelvins.

    if you add 50 Kelvins to 273.15 Kelvin you get 323.15 Kelvin, which is equal to 50 Celsius.
  15. Aug 16, 2006 #14


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    Have you read ANY of the posts in this thread?

    You fail to differentiate between specific temperatures and the magnitude of a change of temperature. There is actually notation which specifies this. We have:

    10C = 274.150K

    but at the same time we have:

    1C0 = 1K0

    Notice the difference in location of the degree symbol. When it is to the right of the number it refers to a specific point on the scale, when it is to the right of the letter (C, k or F) it means a CHANGE on that scale.

    Give it some thought.
  16. Aug 16, 2006 #15
    ahhhhhhhhh thanks
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