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Old 02-14-2009, 08:40 AM
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Question Carnot cycle net work done equation

Hi Everyone
Does anyone know how I should use this equation to find "W"? the equation is W = mRln(V2 / V1) = (T1 - T3) I originally thought that maybe w equalled mRln(V2 / V1) or (T1 - T3), but they give different awnsers. Can anyone help?
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Old 06-30-2009, 06:43 AM
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Default Carnot cycle net work done equation

Equation is correct W=mRTln(V2/V1).
george.Romania.

Last edited by george; 06-30-2009 at 06:46 AM.
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Old 07-04-2009, 12:45 PM
Pmb Pmb is offline
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Quote:
Originally Posted by Slaternater View Post
Hi Everyone
Does anyone know how I should use this equation to find "W"? the equation is W = mRln(V2 / V1) = (T1 - T3) I originally thought that maybe w equalled mRln(V2 / V1) or (T1 - T3), but they give different awnsers. Can anyone help?
I don't understand where you got that expression from.

I'm a bit rusty with thermo so please bear with me. In fact I plan on spending this summer suping up my thermo skills. The Carnot cyle consists of two types of curves, and adiabat compression/expansion (a proces in which no heat flows) and an isothermal compression/expansion. (process for which the temperature is constant). The total work done in a Carnot cyle equals the area enclosed by the carnot cycle.

The cycle consists of

(1) Isothermal compression from V_a to V_b.
(2) Adiabatic compression from V_b to V_c.
(3) Isothermal expansion from V_c to V_b.
(4) Adiabatic expansion from V_b to V_a.

The work done along an isotherm during an isothermal compression is

W_isotherm = mRln(V_f / V_i)

The work done along an adiabat during compression is

W_adiabat = c_v(T2 - T1)

where c_v is the specific heat of the gas at constant volume (I hope I didn't make any errors in the signs here).

The net work done by a gas during a Carnot cycle is calculated in these notes
http://physics.usask.ca/~plyukhin/ep271/notes/note8.pdf

Last edited by Pmb; 07-04-2009 at 12:58 PM.
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Old 07-17-2009, 01:47 PM
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Work per cycle = (isothermal relaxation machine work) x (yield)

W=(mRTlnV2/V1)x(T1-T3/T1); T1=T =>
W=(MRlnV2/V1)x(T1-T3)
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