The IB Physics Compendium 2004 3. THERMAL PHYSICS 3.1. From mechanics to thermal physics Many concepts in thermal physics are based on mechanical concepts - for example temperature which is a measure of average kinetic energy. When mechanics is applied on millions and millions of atoms or molecules moving and colliding, it is often not possible to study every one in detail, but they are represented by "collective", more easily measurable quantities. 3.2. Temperature, internal energy and heat Temperature …showed first 75 words of 5986 total…

…showed last 75 words of 5986 total…water it is 290K. We then get the total change in entropy as DStotal = DShot + DScold = (-Q/310K) + (Q/290K) which is positive. The total change in entropy is always positive when all relevant parts of the universe are included in the calculation. This was a calculation of the DS, but defining S itself is more complicated and requires applying statistics and probability to the microscopic and macroscopic states of the molecules in an object.]