Questions tagged [thermodynamics]
Covers the study of (mostly homogeneous) macroscopic systems from a heat/energy/entropy point of view. Consider also using tag: [statistical-mechanics].
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Vapour-liquid equilibrium of solution [closed]
I have a bottle with a mix of propane and butane. The mix is partially liquid and partially vapour at room temperature. What's the pressure of it? I can get the vapour pressure of both gases ...
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Can we enhance a thermal gradient by combining a dark surface and a shiny surface with an external glass layer?
I refer to the article at this site:
http://solarcooking.wikia.com/wiki/Solar_Kettle-Thermos_Flask
As we know, dark surfaces absorb radiation (eg. solar water heater), while shiny surfaces reflect ...
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Kindling to make a fire
I know that rubbing stuff like dry grass or wood on firewood works to make a fire but why does it work?
I think it is because the friction produces heat but then how come our hands don't get on fire ...
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>50% Heat Engine + Heat pump [closed]
I know entropy rules force my statement to be FALSE.
But anyway I haven't been able to find the problem in the statement.
Suppose:
We have a perfectly isolated cold reservoir at $T_c = 100 K$
We ...
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Thermodynamic / Thermal Property
What is the definition for
(i) Thermodynamic Property &
(ii) Thermal Property?
What are the subtle distinctions in the Thermodynamic Properties and Thermal Properties?
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What is the physical explanation for the heat equation?
We know that $\int{\vec v.\vec n \,\ d a}$=$\int{\nabla^2(u)\,\ dx \,\ dy \,\ dz}$ where $\vec v$ is the velocity of the heat flow and $u(x,y,z)$ is the temperature at the point $(x,y,z)$.and $ \vec v=...
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Boiling water function
i want to make a program that realistically boils water with all the variables but know near nothing about the math
i got the energy transfer equation down
but this seems to be giving me some ...
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How long will pressure exist in this case?
I'm currently fabricating my project, which currently exists only on paper, and there's one question to which I have stumbled today.
Suppose, that I have a pressure vessel capable of holding upto ...
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entropy change during irreversible heat loss [duplicate]
When a thermodynamic system gains heat if the heat gain is irreversible then there is a entropy generation along with the entropy transfer..so is there a similar entropy generation associated with ...
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Specific heat ratio range [closed]
I know that the specific heat ratio, $\gamma$, exists in the range $1 <\gamma< 2$, and I am required to demonstrate a proof of this.
I have come across the following proof (but I don't really ...
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Why does a thermal memory need a thermal bath?
In the article "Thermal Memory: A Storage of Phononic Information
Phys. Rev. Lett. 101, 267203 – Published 29 December 2008" it's said that a thermal memory need a thermal bath, similar to a power ...
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time factor of heat increase (specific heat)
It takes 4 joules to bring 1 gram of water up 1 degree, but for how much time - 1 second? If not, how much and how to calculate it?
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Calculate mass of ice needed to cool water $\Delta$T degrees
I have a question about a thermodynamics formula I'd like to apply in my solution to a problem.
The problem is "Determine how much ice one needs to toss into boiling water of mass $m_{w}$ such that ...
user44816
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efficiency of a stirling engine with spring
I have used the concept of stirling engine with a spring instead of any gas to make an engine....i want to calculate the efficiency of it...here's a pic:
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Problem Boltzmann distribution [closed]
I am trying to solve a problem about boltzmann distribution.
If(A)=0.74
Uf(V)=0.037
Ia(A)=0.130
I have to find ...
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How to prove R value for insulation?
I ran some tests on different types of insulation. I heated water, and placed it into an insulated box. The temperature was recorded every minute, for the water, as well as the air. The insulation ...
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Potential energy for different states
While studying thermal physics at school, I have been taught that solids simply have more potential energy than the liquids and gases. Note that it was said that this potential energy is due to the ...
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Why the temperature of gas produced by firework falls rapidly?
When a firework explodes, the powder in the firework burns rapidly to produce a small volume of gas at high temperature and pressure. Can anyone explain to me why the temperature of the gas falls ...
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Is it possible (theoretically) to divide Black Hole into two parts? [duplicate]
I have read that it's not possible.
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heating verses air conditioning [closed]
My Co-workers and I are trying to figure this out, but can't think of a logical answer. It's probably an easy one, but I'll ask anyway-
Ok, the heater is set at 73 degrees.
The a/c is set at 73 ...
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Why do phonons cause excellent heat conduction in diamonds?
Phonons are the quantum of lattice vibrations in crystals and are not to be confused with photons, the gauge bosons of the electromagnetic force. Apparently, they contribute to heat conduction, but I ...
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For how long can we make an air balloon stay flying via remotely controlled heat system?
I wonder how a function $$f=f(h, m_{\mathrm empty}, V_{max}, T_{h}), $$ with the top height $h$, the empty mass $m$, the maximum volume $V_{max}$, and the temperature of the heater $T_{h}$ would look ...
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How can we prove each energy in different condition become minimum when thermal equilibrium
My question is like the title. We know in
condition : const volume, entropy -> internal energy(U) reach minimum when thermal equilibrium.
condition : const pressure, entropy -> enthalpy(H) ...
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How do we know that the idea of entropy is true? [duplicate]
How do we know that the idea of Entropy is True?
What I mean is,
Do we really know "Scientifically" that Entropy of Universe is Bound to increase?
Or
We know it "Statistically" that Entropy of ...
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Statistical physics is unable to prove that $TdS=d\overline{E}$
I will pose $k_B=1$.
Suppose a system of statistical physics with the constraints:
$$
\begin{align}
1&=\sum_{q\in\mathbb{Q}}\rho(q)\\
\overline{E}(\beta)&=\sum_{q\in\mathbb{Q}} E(q)\exp(-\...
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Ideal gas and piston [closed]
In cylinder with movable piston a gas is closed. It has been noticed that if cylinder was thermally isolated, quasi-statistical growth of volume resulted in reduction of pressure according to equation:...
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3
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How can liquids be two temperatures in different spots?
How come water can be two temperatures at different 'spots' after adding colder water to hot water? The density and viscocity is the same, so what makes them be seperate temperatures in seperate ...
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How do I calculate the amount of heat transfer to agitated air?
Suppose my room is x degrees C. The air in my AC ductwork is a constant y degrees C and is blowing at z m/s. We assume there is no heat transfer from the outside. How can I figure out how long it will ...
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What is the effect of atmospheric pressure on the vapour pressure of water?
This question relates to a planned test simulating cold, humid air flowing inside a cold pipe at altitude and measuring the ice that is formed inside the pipe.
I have a value from:
https://courses....
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Does a piece af mass with human-like heat exchange mechanisms, heats up in dry air with a temparature greater than that of the mass?
Imagine a piece of mass (equal to the mass of an average person and with the same heat conductivity and ratio of volume and area of an average person) with inbuilt mechanisms to transport the intaken ...
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Is absolute zero possible in a complete vacuum? [duplicate]
Thermal energy is the energy an object due to the motion of it's molecules. This means as long as an objects molecules have kinetic energy, it will not reach absolute zero. Does that mean if there was ...
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How long would it take for the solar core to destroy Earth? [duplicate]
If Earth were at the middle of the solar core, how long would it take to destroy the planet?
Furthermore, how would the planet be destroyed?
To consider the planet to be destroyed, it must be ripped ...
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Convert ambient heat into electricity without violating laws?
This is an idea I've been playing around with for a while, even though many people tell me it's impossible. However, as far as I can tell, it does not actually violate the laws of physics. I am ...
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Is entropy of the universe constant?
Studying the thermodynamics of the early universe we arrived at the conclusion that entropy of the universe has to be constant for the entropy to be a function of state. But from basilar ...
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Speed of sound violating speed of light
At the Large Hadron Collider (LHC) a temperature of 7.2 trillion kelvin is recorded(really?!)... We know that the speed of sound increases by 0.61m/s for 1°C.So if at the same instant sound is ...
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Confusion regarding Gibbs energy [closed]
$G = H - PV$
$H~=~U~+~PV$
$U~=~TS~-~PV$
$G~=~TS~-~PV~+~PV~-~TS~=~0$
This is paradoxical as it implies that Gibbs energy is always zero. Where am I wrong?
EDIT:-
I have resolved the paradox.
$dU = TdS -...
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Why north & south pole are very cold? [closed]
I know in these regions sunlight barely falls & sometimes it won't fall at all.
If sunlight doesn't fall for a very long time it doesn't mean that the whole region should become very cold.
For ...
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Is there a explanation to why bodies with higher heat capacity transfer heat to bodies with lower heat capacity?
We know that $C$=$mc$ Where($m$ is the mass of the body and $c$ is the specific heat) , A body
$M_1$ with $C_1$ and another body $M_2$ with $C_2$ where ($C_1$ $\gt$ $C_2$), What is the reason that ...
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What would happen if a solid ball of helium suddenly appeared on the bottom of a deep sea? [closed]
Imagine that a solid ball of helium (at zero Kelvin) appeared at the bottom of a deep-sea on Earth? Say the ball has a radius of 100 meters and that the sea is 10 kilometers deep. The temperature of ...
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Contradiction on Entropy of the "universe" decreasing
I have hit what seems to be a contradiction concerning entropy.
In my class, we measured the entropy change of photosynthesis which is obviously a non-spontaneous process. We used the formula,
$$\...
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QM explanation (electrons and lattice structure) why aluminum does not get hot in an oven?
I have read this question:
Why can I touch aluminum foil in the oven and not get burned?
But the answers therein only explain on a classical level why aluminum foil being a very good conductor and ...
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Why does a bimetallic strip bend when heated?
This is a bimetallic strip:
When you heat the strip why doesn't this happen?(I know that the strips are somehow attached to one another and that probably has something to do with the bending. But I ...
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Can anyone prove this overstated-but-almost-never-justified fact from thermodynamics?
Clausius inequality states that $\oint {\delta Q\over T}$ equals zero for a system undergoing a reversible cycle, whereas it can’t be greater than zero for an irreversible cycle.
But everywhere, I ...
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Does burning always produce a flame and if so why?
I have been looking at thermodynamics and I tried to find the answer on the internet but nothing of relevance came up and even this site did not have the answer.
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Is anything wrong with the given statement? [closed]
If we take randomly any two bodies, the one with the higher temperature will contain more heat.
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Working of thermometer and mercury
If mercury is a poor conductor of heat, then how does it work in a thermometer?
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Why is each snow flake different?
What are the factors that determine the patterns of snow flake formation? Would pressure and the rate at which a snow flake freezes make a difference? Does the PH and impurities make a change in the ...
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Global warming: change in Earth's potential energy
It is quite common to hear in newspapers and television about the increasing temperature, i.e. global warming.
But I am interested in something else.
How does global warming affect the internal ...
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Examples of experiments replicating the idealized greenhouse model
I'm looking to find experiments that experimentally demonstrate the Idealized greenhouse model.
So far all the experiments I've come across do not quite demonstrate the model, but something else.
...
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