Revision as of 02:46, 29 August 2004 editBryan Derksen (talk | contribs)Extended confirmed users95,333 edits Category:Physics← Previous edit | Revision as of 00:43, 19 September 2004 edit undoKappa (talk | contribs)36,858 edits dab kappaNext edit → | ||
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The '''adiabatic index''' of a ], usually denoted by the symbol κ (]) (also called γ), is the ratio of its specific heat at constant ] (c<sub>p</sub>) to its specific ] at constant ] (c<sub>V</sub>). | The '''adiabatic index''' of a ], usually denoted by the symbol κ (]) (also called γ), is the ratio of its specific heat at constant ] (c<sub>p</sub>) to its specific ] at constant ] (c<sub>V</sub>). | ||
:κ = c<sub>p</sub>/c<sub>V</sub> | :κ = c<sub>p</sub>/c<sub>V</sub> | ||
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:c<sub>p</sub> - c<sub>V</sub> = 0.4 | :c<sub>p</sub> - c<sub>V</sub> = 0.4 | ||
Kappa can also refer to several other things, but it can usually be determined by the context which one. Sometimes the greek letter gamma γ is used. | |||
] | ] |
Revision as of 00:43, 19 September 2004
The adiabatic index of a gas, usually denoted by the symbol κ (kappa) (also called γ), is the ratio of its specific heat at constant pressure (cp) to its specific heat at constant volume (cV).
- κ = cp/cV
One can easily understand the relation if one thinks of the following experiment: A cylinder closed at one end with a blocked piston is filled with air. This cylinder is then heated. Since the piston cannot move the volume is constant. Temperature and pressure will rise. One stops the heating noting how much energy one has added to the system (cv) and frees the piston. The piston will move outward and by adiabatic expansion the gas cools. To bring the temperature of the gas to its former level one has to heat it a little bit. This extra heat amounts to about 40% of cv thus:
- cp = 1.402 · cV
A value often used in aerodynamics is
- cp - cV = 0.4
Kappa can also refer to several other things, but it can usually be determined by the context which one. Sometimes the greek letter gamma γ is used.
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