![]() In other words, the total amount of “heat” inĪbout how much heat there is in the gas is meaningless. ![]() Himself thought that something else besides total energy was conserved: theīut we know better: in a Carnot cycle, the heat leaving the gas on theĮntering earlier, by just the amount of work performed. Of the gas is the same at the end of the cycle as it was at the beginning, but We know, of course, one thing that doesn’t change: the internal energy To get a clue about what stays the same in a reversibleĬycle, let’s review the Carnot cycle once more. Heat Changes along Different Paths from a to c Labeled entropy that doesn’t change in a reversible process, but always Parameter? The answer turns out to be yes: there is a parameter Clausius The “amount of irreversibility” to be measured? Does it correspond to some thermodynamic Reversible engine has to equal that of the Carnot cycle, and any nonreversible The second law, that heat only flows from a warmer body to aĬolder one, does have quantitative consequences: the efficiency of any Other names, but those are merely notational developments.) ![]() Work, the unit wasn’t called a Joule, and the different types of energy had Up to get the total and that will remain constant. Heat units and energy units, calories to joules, since all the other types ofĮnergy (kinetic, potential, electrical, etc.) are already in joules, add it all His aim was to express both laws in aĬonservation of total energy including heat energy -is easy toĮxpress quantitatively: one only needs to find the equivalence factor between So what, exactly, is entropy, where did this word comeĬlausius in 1865, a few years after he stated the laws of thermodynamics This was called the Heat Death of the Universe, and may still be what’sīelieved, except that now everything will also be flying further and further Used to describe the approach to an imagined final state of the universe whenĮverything reaches the same temperature: the entropy is supposed to increase toĪ maximum, then nothing will ever happen again. Synonym for chaos, for example: the entropy in my room increases as the The word “entropy” is sometimes used in everyday life as a Previous index next A New Thermodynamic Variable: Entropy
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