Testing Kelvin Planck's Second Law of Thermodynamics

AI Thread Summary
The discussion focuses on proving the Kelvin Planck statement of the second law of thermodynamics, which asserts that heat cannot be completely converted into work without some being transferred to a cold body. The original poster seeks a proof that demonstrates this principle independently, without relying on other formulations of the second law or the Carnot cycle. They suggest that if the Clausius statement (heat flowing from cold to hot without work) is false, it implies the Kelvin Planck statement must be true. The poster has made some progress in their analysis but is uncertain about its validity and seeks more rigorous methods or feedback from others. The conversation emphasizes the need for a clear, independent proof of the Kelvin Planck statement in cyclic processes.
sadhu
Messages
155
Reaction score
0
can anyone proove "kelvin plank" statement of second law of thermodynamics or atleast show that it is always followed in any cyclic process...
 
Physics news on Phys.org
am i gone mad ,no one knows it...come on
 
sadhu said:
can anyone proove "kelvin plank" statement of second law of thermodynamics or atleast show that it is always followed in any cyclic process...
I think this question is asking you to prove that the Kelvin Planck statement of the second law follows or is equivalent to the Clausius statement of the second law.

First of all, you should state the Kelvin Planck statement of the second law and also state the second law (Clausius statement).

Then assume that the Clausius statement is not true (heat flows from cold to hot without adding work) and show that it follows that Kelvin Planck is not true. So not-Clausius is false (and not-KP is false): ie.Clausius must be true (and so Kelvin Planck must be true).

Hint: assume that heat Q can flow from cold to hot without doing work, then put a heat engine in there which takes the same amount of heat (Q) from the hot reservoir as flows from the cold and produces W work delivering Q' heat flow to the cold reservoir. You can see that the hot reservoir is not really doing anything (Q flows in and Q flows out) so you can ignore it and just consider Q flowing from the cold reservoir to the heat engine. AM
 
Last edited:
sorry
but what i mean is to show that the statement
"kelvin plank"
"heat cannot be converted into work with 100% efficiency(without giving some to cold body)"

is followed in every cyclic process ,without using other forms of the 2 law or carnot
cycle or any such statement which is a part of second law or uses it .

i.e to prove it independently

because it will automatically prove every other part of it except the one including the concept of entropy which i think can,t be prooved..

well i have made some progress in it but i am not sure that my proove is genuine one or not hence i wanted someone to come up with some other more rigourous methods to do it.

but thanks for your reply...:approve:
 
Last edited:
search for proof

well if you all remembered i recently asked the question about prooving(not deriving) 2 law
but no one gave me the answer i wanted. so i was left to do on my own ,well i came up with an
analysis but don't know whehter it is right or wrong
so here i put to everyone to analyse it and check
 

Attachments

Thread 'Gauss' law seems to imply instantaneous electric field'
Imagine a charged sphere at the origin connected through an open switch to a vertical grounded wire. We wish to find an expression for the horizontal component of the electric field at a distance ##\mathbf{r}## from the sphere as it discharges. By using the Lorenz gauge condition: $$\nabla \cdot \mathbf{A} + \frac{1}{c^2}\frac{\partial \phi}{\partial t}=0\tag{1}$$ we find the following retarded solutions to the Maxwell equations If we assume that...
I passed a motorcycle on the highway going the opposite direction. I know I was doing 125/km/h. I estimated that the frequency of his motor dropped by an entire octave, so that's a doubling of the wavelength. My intuition is telling me that's extremely unlikely. I can't actually calculate how fast he was going with just that information, can I? It seems to me, I have to know the absolute frequency of one of those tones, either shifted up or down or unshifted, yes? I tried to mimic the...
Back
Top