Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Problem Relating Temperature and Thermal Energy

  1. Nov 26, 2012 #1
    1. The problem statement, all variables and given/known data
    An ideal gas is at 40°C. The gas is cooled, reducing the thermal energy by 35%. What is the new temperature in °C?


    2. Relevant equations
    I'm not sure there is one?


    3. The attempt at a solution

    Since, in an ideal gas, thermal energy is proportional to temperature, I multiplied 40°C by .35 and got a change of 14°C. After subtracting, I get a resulting temperature of 26°C. But, the online program is telling me this is incorrect? Am I doing something wrong?

    Thanks!
     
  2. jcsd
  3. Nov 26, 2012 #2

    ehild

    User Avatar
    Homework Helper

    Thermal energy of the ideal gas is proportional to the absolute temperature.

    ehild
     
  4. Nov 26, 2012 #3
    Ohh, ok. I got it now, thanks! :) The answer is -70C.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook