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Thermal Physics

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6 Feb 2007 18:11:07 IST

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1369

work done in heat processes

None

somebody plese tell me in which of the process(isothermal,adiabatic,isochoric,isobaric) is the work done maximum with explanation.

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Comments (12)

phalgun_g

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6 Feb 2007 18:35:31 IST

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it is in a adiabatic process...

cos its definetly not isochoric ...

and at constant pressure think about a pressure cooker ...

and not isothermal because in some cases work is done by increase in temperature...

so its goy to be adiabatic....

plz do tell me if im wrong....

Eshaan Gupta

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6 Feb 2007 20:07:26 IST

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the answer adiabatic is right but i was thinking that since in isothermal process T remains constant so the internal energy must be 0 and applying first law of thermodynamics Q=U+W we will get Q=W, i.e, all the heat must have been utilised for doing the work.

Anshuman Johri

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6 Feb 2007 20:08:34 IST

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By the first law of thermodynamics dQ=dW+dU.

When an isothermal process is considered, whole the energy supplied of taken affects only the work done. This is becoz in an isothermal process the total change in internal energy is always 0 i.e. dU=0 => dQ=dW.

So the work is done maximum in an isothermal process.

Eshaan Gupta

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7 Feb 2007 17:59:18 IST

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is this valid for expansion,compression or both??

Sumit

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8 Feb 2007 22:17:23 IST

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if we consider the area under the curves in the p-v graph,we will see that work done is max under the curve for isothermal curve....so i think work done is max 4 isothermal process.

sravan

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8 Feb 2007 22:19:28 IST

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Adiabatic process

Sumit

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8 Feb 2007 22:30:07 IST

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oops....sorry...i confused the isothermal curve for the adiabatic curve!!
sravan is correct,work done is maximum for adiabatic process and it follows easily from the area under the curves.

Eshaan Gupta

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9 Feb 2007 18:40:26 IST

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WILL SOMEONE GIVE ME A DEFINITE ANSWER SOME SAY ISOTHERMAL OTHERS ADIABATIC..MAYBE EXPERTS OPINION NEEDED HERE.

vishak p

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11 Feb 2007 22:03:56 IST

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well dear, the adiabatic curve has a steeper slope if u differntiate the equation of this process that that of isothermal.hence, area under adiabatic curve is more !

Aatish Pandit

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11 Feb 2007 22:17:36 IST

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All of you, have a look !!

IF YOU DRAW A P-V GRAPH THEN AREA UNDER THE CURVE WILL GIVE YOU THE AMOUNT OF WORK DONE, WHICH IS MAXIMUM FOR ISOBARIC PROCESS. DO IT YOUR SELF AND SEE.

Sagar Saxena

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22 Oct 2008 03:32:59 IST

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work done is depend on the are under the PV graph::

isobaric > isoothermal > adiabatic > isochoric

Siddhartha Gupta

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14 Nov 2008 10:41:27 IST

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I guess sagar's (sir) answer is correct ...the graphs are like:

isobaric: (PV graph)

here, work is maximum coz area under line is maximum .

Isothermal and Adiabatic:

Clearly , the Isothermal curve occupies more area .

& for Isochoric process:

Here , area is zero coz is zero, so work is zero ...

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