We know that if we brought a body at temperature T' in contact with a heat reservoir at temperature T (where T' < T) entropy of the universe increases.(adsbygoogle = window.adsbygoogle || []).push({});

What if we brought a body at temperature T' in contact with a reservoir at temperature T ( where T' > T)?

It is supposed also that the entropy of the universe increases.

But when am trying to proof it mathematically, I fall into another question: in the first case, the temperature of the heat reservoir remains the same, it is a reservoir after all, but in the second case, does the temperature of the body stay the same? Or it decreases by a certain amount. And the heat reservoir in the second case, does it temperature increases? Or since it is a heat reservoir, it should change the temperature of the body and not vice versa. I should have some misconception going on.

Do you have any idea?

Thanks in advance.

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Entropy of the universe increases

**Physics Forums | Science Articles, Homework Help, Discussion**