Problem Relating Temperature and Thermal Energy

AI Thread Summary
An ideal gas initially at 40°C is cooled, resulting in a 35% reduction in thermal energy. The relationship between thermal energy and temperature for an ideal gas is based on absolute temperature, not Celsius. The correct calculation involves converting the initial temperature to Kelvin, applying the percentage reduction, and converting back to Celsius. The final temperature after the reduction is -70°C. Understanding the importance of absolute temperature is crucial for solving such problems correctly.
chinnie15
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Homework Statement


An ideal gas is at 40°C. The gas is cooled, reducing the thermal energy by 35%. What is the new temperature in °C?

Homework Equations


I'm not sure there is one?

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!
 
Physics news on Phys.org
Thermal energy of the ideal gas is proportional to the absolute temperature.

ehild
 
Ohh, ok. I got it now, thanks! :) The answer is -70C.
 

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