All Questions
11
questions
0
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2
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78
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Is this set up a reversible process and is the adiabatic equation of state applicable here?
I had this question in a recent test:
My teacher while discussing this question used the adiabatic equation of state PV^gamma=constant to solve for length L (options C and D). And used work energy ...
- 105
0
votes
1
answer
115
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Deduction of the entropy balance equation with input and output of matter by convection (mass flow)
In many books of Engineering thermodynamics, the entropy balance equation is wrritten as
$\frac{dS}{dt}=\Pi_S+I_S$
$I_S=\sum_{j=1}\frac{\dot{Q}_{j}}{T_j}+\sum_{i=1}\dot{m}_is_i-\sum_{e=1}\dot{m}_es_e$
...
- 3
0
votes
1
answer
87
views
Momentum-derivative of energy when mass is not constant
We know by multivariable calculus, that a scalar multivariable function such the energy function $E=E(\vec{P},\vec{L},X_{0},X_{1},...,X_{n})$, using the chain rule, can be expanded as follows:
$\frac{...
- 3
0
votes
1
answer
216
views
In terms of heat, temperature and the first law of thermodynamics: Is defrosting an energy saver
If I were to defrost my freezer would I save energy?
From what I have read I would expect the answer to this question to be no, however it would be great to hear if Im wrong.
I say it wouldn't save ...
- 57
0
votes
1
answer
397
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PV-diagram: If part of diagram is isotherm is there no work?
Ive filled out this pv-diagram table. Ive done one similar to this diagram , however the other segment c->a was a straight line. In this example its curved.
Im wondering if segment c->a is an ...
- 57
3
votes
0
answers
276
views
Lagrangian formulation of a themodynamics problem
I was wondering whether it is possible to derive the model of a thermodynamical system by combining thermodynamic equations and Lagrangian mechanics.
Let's consider the following closed system.
A ...
- 43
9
votes
2
answers
2k
views
Free energy of coupled classical harmonic oscillators
I'm looking to find the thermodynamic (NVT) free energy of a classical coupled harmonic oscillator system such as the one below:
(image taken from http://openmetric.org/StatisticalPhysics/equilibrium/...
- 949
0
votes
1
answer
258
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Ideal gas in ensemble
I want to calculate the phase space density for a single ideal gas particle in a microcanonical ensemble.
I know that the partition function is given by the well-known expression that you find for ...
- 97
6
votes
2
answers
6k
views
Confused with stress, strain and linear thermal expansion
Four rods A, B, C, D of same length and material but of different
radii r, 2r , 3r and 4r respectively are held between two rigid
walls. The temperature of all rods is increased by same amount. ...
- 7,335
0
votes
1
answer
3k
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What happens to temperature when pressure is constant in a cylindrical piston of saturated liquid ammonia?
Let's say I have a cylindrical piston containing saturated liquid ammonia that is fitted with an electrical heater and a paddle wheel for stirring at an initial pressure and an initial temperature. ...
- 1,158
18
votes
1
answer
3k
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Mechanics + Thermodynamics: Bouncing Ball
In preparation for an exam, I'm revisiting old exam questions. This one seems neat, but also quite complicated:
A soccer ball with Radius $R=11cm$ is inflated at a pressure of $P =9 \times 10^4 Pa$,...
- 14.9k