Himanshu posted an Question
April 28, 2020 • 08:52 am 30 points
  • IIT JAM
  • Physics (PH)

Thermodynamics2

In first pic there was question and in second there was solution (given from ur side) Why here we keep temperature in celcius not in Kelvin??

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    Ruby negi

    alwys take temperature in kelvin, but here in the solution, u need temperature difference (T1-T2) so temperature difference is same in Celsius or in kelvin.. so no need to worry, if u convert Celsius into kelvin and then do this problem, ans is same..

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    Abhishek singh Best Answer

    Very Important : The formula for efficiency = (1-T2/T1) is only applicable in Kelvin units!! Yes, you have pointed out a valid doubt. But in the solution above, we need temperature difference, so (273+50 - (273+10)) = 40 K. We skipped that step in the solution. But it was always in our minds. Now let me give you a fact, Temperature is the only quantity, which has unit conversion in addition form( i.e. 273 + x°C = (273+x) Kelvin. Unlike any other units, it you double the temperature in °C, the temperature is not doubled in Kelvin! Now an important hint: whenever there is temperature difference is given, or you need temperature difference in your formula, always assume it in Kelvin! (As you know by now, that there is no difference when talk about difference in temperature). So always assume in Kelvin units. Best regards.

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    Shanu arora best-answer

    it actually doesn't matter even if we keep temp in Kelvin or celsius here as far as the temp diffenrce is concerned and the temp diffenrce remains same ( 50+ 273 - (10+273) ,so we have neglected that, but it's good habit to do things in the units required and can do in Kelvin as well. feel for any doubts best regards.

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