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4
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1answer
145 views

How does the internal energy and entropy depend on mass?

I've found this thermodynamics question: Given a fluid described by the following equations: $$PV^{1/3}=aT^3 ,\quad U=3aT^3V^{2/3}, \quad S=\frac{9}{2}aT^2V^{2/3}$$ The parameter $a(n)$ ...
3
votes
1answer
765 views

Simple thermodynamics basics - can internal energy be calculated?

Well this got me stumbled, because I've been wondering what the "question" is. One of the example examns got the following question (strangely there are no supplied solution books): A $0.2 {\rm ...
3
votes
0answers
23 views

Energy needed to raise energy level of an atom? [duplicate]

Suppose I have an atom at rest which is at energy level $E_i$. Would it be possible to raise it to the next higher level $E_{i+1}$ by shooting a photon of energy $E_{i+1}-E_i$ at it? I ask because ...
3
votes
0answers
479 views

How do I determine the Internal Energy of ammonia at a pressure in temperature when the steam table doesn't say it

I just bought a steam table for my thermodynamics class since they don't allow use to use the one from the book for the tests. This one is different from the one in my textbook as it doesn't give the ...
2
votes
3answers
3k views

Kinetic energy and momentum conservation in an explosion?

My physics book says, "A firecracker sliding on ice has the same total momentum before and after it explodes." I understand this part. This is because of Newton's 3rd law, and no external forces. This ...
2
votes
1answer
223 views

How to express the heat capacity in terms of heat?

The first law of thermodynamics divides the internal energy change into contributions of heat and work. $$\text dU=\omega_Q-\omega_W,$$ Here I chose the notation to emphasise that the two parts are ...
1
vote
2answers
133 views

Does performing a measurement on a system change its internal energy?

I'm studying Quantum Mechanics in my spare time from a general point of view (no technical details) so some fundamental question came into my mind: How is it possible to detect a single photon ...
1
vote
2answers
1k views

How is it possible to equate the internal energy at constant volume with the internal energy of an adiabatic process?

I hope my question makes sense. My problem is that, I have read through numerous textbooks that nC(cons. volume)dT = -PdV when deriving the relationship between T and V for an adiabatic process, ...
1
vote
1answer
73 views

Enthalpy in thermodynamics!

What does enthalpy tell us about? According to definition; it is the total heat content of a system, if it is the total heat content of a system then what is Internal Energy? Since we know, ...
1
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0answers
69 views

Where does the relation $u=h_f-RT+(c_p-R)(T-T_0)$ come from?

I'm working on a college project for a subject called Motorcycle Engineering, and in this project I'm supposed to do some reverse engineering on a MATLAB program to model the engine of the motorcycle. ...
0
votes
2answers
45 views

Partition Function - TOTAL internal energy vs Average Energy

Given a partition function Z, the books sometimes uses the terms 'total internal energy' and 'average energy' exchangeably. It confuses me to no end. On one hand they say that Internal energy is ...
0
votes
1answer
150 views

Why doesn't intensity of light affect the emission of electrons?

So electrons of specific atoms have a minimum amount of energy needed to escape the atom, called the work function, W. Now let's say that you emit a certain frequency of light, and $hf<W$. However, ...
0
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1answer
64 views

Performing work on a box of gas by lifting it, and first law of thermodynamics

What happens if we lift a box of ideal gas? Work is done to the box but no heat is getting into it. So does it's internal energy increase by the amount of work done? Or is it that lifting is not ...
0
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0answers
19 views

Is this how I find the rate of change of internal energy for filling a vessel?

If I am filling a tank with something (lets say air) and both its volume and pressure are changing with time (It's not rigid), it it safe for me to say: $$u=h-Pv$$ ...
0
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0answers
135 views

2 streams going into an engine and 2 come out. Find the enthalpy?

Problem: Steam supply to an engine is made of two streams that mix before entering the engine. Stream 1 flows at a $.01\frac{kg}{s}$ with an enthalpy of $2952\frac{kJ}{kg}$ and a velocity of ...