All Questions
61
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Entropy in irreversible adiabtic process
We know that,
$$dS=\dfrac{\delta Q_{rev}}{T}$$
If you have an irreversible adiabatic process between two thermodynamic equilibrium end states of a system, there exists no possible reversible adiabatic ...
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Given state $P$, does the set of all forward adiabatic processes and reversed adiabatic processes reach all states in the state space?
Let $A$ be a thermodynamic system and let $\Sigma$ be its state space. By the state postulate, if $A$ has $n$ two-way work channels (i.e. ways in which work can be done both positively and negatively ...
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3
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218
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Why can't entropy decrease for an adiabatic and closed system?
In equations (10) and (11) of this article by Curzon on the adiabatic piston, Curzon uses that a system which is thermally insulated cannot have its entropy decrease (irrespective of anything else ...
- 1,095
-4
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4
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171
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Derive $ΔS = Nk\ln(V/V_0)$ using fundamental equations of thermodynamics [closed]
I am considering a system with an ideal gas undergoing an adiabatic expansion. The initial volume is $V_0$ and final is $V$.
From this, How do I derive $\Delta S = Nk\ln(V/V_0)$ using fundamental ...
- 33
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4
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Why can't a heat engine have 100% efficiency?
Using the idea of isotherms and adiabats, I came up with the following argument to convince myself. First imagine the working gas within the system being heated along an isochore (hence all heat ...
- 75
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1
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136
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What is the entropy of the system, surroundings, and universe of a reversible adiabatic process?
I had a homework question that confused me a little bit. We were told to find the change in entropy of the system and the universe of a process. This process is an adiabatic, reversible process. From ...
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2
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177
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Understanding page 141 of Blundell’s Concepts in thermal physics
On this page (in the second edition), there is a figure containing two states A and B of a system:
There are two paths between A and B: one is an irreversible change, and the other is a reversible ...
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6
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5
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Why isn't the free expansion of a gas in an adiabatic container isentropic?
If you expand a gas adiabatically using a piston, the process is isentropic. However, if you simply remove the piston and let the gas expand freely, the process is now not isentropic. What makes these ...
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3
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Proof of Caratheodory's theorem
Caratheodory's formulation of second law of thermodynamics, also referred to as Caratheodory's principle states
In any neighbourhood of any thermodynamic state $P$ there exist states which are ...
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29
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Is an isentropic process always adiabatic? [duplicate]
I am making an exercise about a pulsating jet engine. There is a part in the cycle of this engine that is an isentropic expansion and i'm wondering if I can use $PV^{g} = cte $ in this process
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3
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150
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Entropy change during adiabatic expansion of ideal gas
I was told that the entropy change is $0$ during adiabatic expansion. However, according to $\mathrm dS=\frac{C}{T}\,\mathrm dT$, $\delta S$ is not zero because temperature is not constant during ...
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1
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Finding equation of internal energy in adiabatic process
I am doing a review of thermodynamic and I encounter the following question,
Show that if a single-component system is such that $PV^k$ is constant in an adiabatic process (k is a positive constant) ...
- 159
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1
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What is the type of system, if I have an opened container with hot water inside, but no heat input to the system?
I have a school project, where I am trying to generate electricity using TEG modules that are attached to an aluminium container that contains hot water. The container is opened and there is no heat ...
1
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1
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149
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Derivation of astrophysical entropy
The definition of entropy in astrophysics is often actually just the adiabatic constant $K$ relating $P=K\rho^\gamma$ where $\gamma$ is the usual adiabatic index, $P$ is the pressure and $\rho$ is the ...
- 205
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Uniqueness of Irreversible and adiabatic processes in finite time
Let the external intensive and extensive "mechanical" variables be denoted by $Y_k, X_k$. These variables are well defined irrespective of the system is in equilibrium or not. For an ...
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