2063: Carnot Cycle

2018-10-24T17:49:32Z

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{{comic
| number = 2063
| date = October 24, 2018
| title = Carnot Cycle
| image = carnot_cycle.png
| titletext = The Carnot cycle is more properly known by its full title, the "Carnot-Tolkien-Wagner Ring Cycle."
}}

==Explanation==
{{incomplete|No tables for texts like this! Please edit the explanation below and only mention here why it isn't complete. Do NOT delete this tag too soon.}}

This comic shows a {{w|Pressure–volume diagram}} which is used in this case for a {{w|Carnot cycle}}, a theoretical thermodynamic cycle and covers most thermodynamics classes which looks very much like the figure drawn. However in this case, [[Randall]] has replaced the labels of the 4 stages of the real Carnot cycle with new ones.

Each step is explained below

{| class="wikitable sortable"
!Step in Comic
!Step in the real Carnot Cycle
!Explanation
|-
|1. Isometric expansion. When heated, the gas becomes larger due to increasing volume
|Reversible isothermal expansion of the gas at the "hot" temperature, Th (isothermal heat addition or absorption).
|The comic text uses a circular argument. Additionally, "isometric" (equal dimensions) could mean that the gas does ''not'' change in volume, in contrast to the change in volume here.
|-
|2. Isotonic expansion. The gas expands further due to dark energy while percent milkfat remains constant.
|Isentropic (reversible adiabatic) expansion of the gas (isentropic work output).
|Isotonic is commonly associated with sports drink (and not thermodynamics). Dark energy is hypothesized to be a cause for the expansion of the universe.
|-
|3. Isopropyl compression. While inflation is held constant, the gas contracts due to tightening interest rates.
|Reversible isothermal compression of the gas at the "cold" temperature, Tc. (isothermal heat rejection)
|Isopropyl alcohol is commonly used for cleaning. Inflation and contraction could refer to changes in gas volume, but the reference to interest rates puts them in the context of {{w|macroeconomics}}. Raising ("tightening") interest rates tends to reduce {{w|inflation}} and/or "contract" the economy. In economics (and other sciences) to better understand model parameter relations, some parameter may be held constant in theory. This could refer to the {{w|Fisher equation}} Holding one parameter constant is also done in the Carnot cycle (for a physical parameter): not only in theory but also in practice! (In free market economies the inflation cannot be directly held constant).
|-
|4. Decline and fall. The gas diminishes and goes into the West while remaining Galadriel, completing the cycle.
|Isentropic compression of the gas (isentropic work input).
|{{w|Galadriel}} is a character in {{w|The Lord of the Rings}}. She is one of the leading {{w|Elf (Middle-earth)|elves}}, a race that in the time of the book is said to be dwindling (in number and importance) in {{w|Middle Earth}} and migrating westward to {{w|Valinor}}. Galadriel is one of the last elves to leave, after successfully resisting temptation to take the One Ring and become an all-powerful queen who dominates Middle-earth, instead saying "I will diminish, and go into the West, and remain Galadriel."
|}

Title text: Richard Wagner's Ring cycle consists of four operas. J.R.R. Tolkien wrote The Lord of the Rings, which some have [[wikipedia:J. R. R. Tolkien's influences#Wagnerian_influences|suggested]] was inspired by Wagner's Ring. Their works are known as {{w|Literary cycle}}s.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

[A Cartesian plot in the first quadrant with axes labelled P on the Y-Axis and V on the X-Axis, with a rhombus-shaped set of four points with arrows between them]

[Upper left point]
1. Isometric Expansion
When heated, the gas becomes larger due to increasing volume

[Middle point]
2. Isotonic expansion
The gas expands further due to dark energy while percent milkfat remains constant

[Bottom Right point]
3. Isopropyl compression
While inflation is held constant, the gas contracts due to tightening interest rates

[Middle Left point]
4. Decline and fall
The gas diminishes and goes into the West while remaining Galadriel, completing the cycle

{{comic discussion}}

[[Category:Line graphs]]
[[Category:Physics]]
[[Category:LOTR]]

explain xkcd - User contributions [en]

2063: Carnot Cycle