Thermodynamics Definition and 1000 Threads

https://www.physicsforums.com/attachment.php?attachmentid=20388&stc=1&d=1252066499When the partition removed, gas flows into the vacuum until all system has a uniform pressure. Now, is it possible to calculate the work? Let's say gas is not an ideal gas.(Freon 12) We know the volumes of both...

Homework Statement A hot gas stream at 600K and 200 kPa is cooled at constant pressure to 300K in a pipe by direct thermal contact with the atmosphere. The mass flow rate of the stream is 0,1 kg/s and the atmospheric temperature and pressure are 300K and 100 kPa. Modeling the gas as an ideal...

A cylinder of cross-sectional Area A is closed by a massless piston. The cylinder contains n mol of ideal gas with specific heat ratio and is initially in equilibrium with the surrounding air at temperature T and pressure P. The piston is initially at height h1 above the bottom of the cylinder...

What are some interesting experiments for doing research in thermal physics or thermodynamics?

Homework Statement Homework Equations $$W=-\int PdV$$ The Attempt at a Solution The gas fills the cylinder slowly and any increase in pressure of system is countered by the upward motion of piston. So the process is quasi-static. But how do I find final amount of gas in the cylinder?

What is enthalpy of a system based on macroscopic POV of thermodynamics and not chemistry? And how do we use it to calculate the total heat transfer in isentropic processes?

This is quite possibly very basic, but I have a horrible habit of forgetting basics as I move up the ladder in difficulty during the semester. This is a question regarding Thermodynamics, taken from Chapter 1; Introduction and the First Law of Thermodynamics of the book Applied Thermodynamics...

Homework Statement I don't need help solving I just need some clarification. Since the carnot cycle is adiabatic, the first law would reduce to work= mass*(change in internal energy). On my test I was asked to calculate the work of the isentropic expansion of a carnot engine with air...

Homework Statement The problem is in the attached picture. I simply do not know what an "equilibrium equation" is and what it means by the composition. My professor is unbelievably difficult to get a straight, understandable answer from. I've already taken thermodynamics, but we did not learn...

I am working on a project which involves air nozzles. I am interested in estimating the time it takes for air particles after they leave the nozzle to reach a particular distance away. I have the following information--- a converging nozzle, the speed with which it is coming out of the nozzle(I...

Can someone please help with hyperelastic theory, I need to know how changes in reversible work are related to energy density function and then to strain and stress tensors. A reference that explains the theories simply would also be appreciated. So far I have failed to find anything relatively...

Homework Statement What is the entropy change of the universe as a result of the following processes: (a) a 1μF capacitor is connected to a 100V electrochemical cell at 0°C, (b) the same capacitor after being charged to 100V is discharged through a resistor kept at 0°C? Homework Equations...

Hello, PF! Days ago, while playing Batman: Arkham Origins, I was wandering through the Batcave when I noticed something that caught my eye immediately. There's a nice, cozy lab in there which includes a blackboard where Bruce Wayne apparently did some kind of thermodynamic calculations, which...

Hello, I need to work on the thermodynamics theory of information, but I can't find real applications aside from the resolution of the maxwell's demon and the szilard engine. I would need more applications... Any idea?

We have 2 (insulated) partitions, one with the gas, another vacuum, separated by a stop cock. We remove the cock, letting the gas expand into vacuum . I understand that since there is no opposing force on the expanding gas ,the work done by the gas is zero . But work done by gas is given by...

[Mentor's note: moved from another forum, so homework template missing.] An upright and ideally heat-insulated cylinder with a diameter of 30 mm is tightly sealed at the bottom by a piston of the mass mk = 2 kg. The cylinder contains 15 g of air. The ambient pressure is pu = 1 bar, the initial...

Homework Statement A 3.60 kg block of copper at a temperature of 92 °C is dropped into a bucket containing a mixture of ice and water whose total mass is 1.50 kg. When thermal equilibrium is reached the temperature of the water is 5 °C. How much ice was in the bucket before the copper block was...

Angular momentum is conserved in a closed system. Is thermal isolation required too? An example special case in mind is a closed cavity high speed rotation. It contains high pressure gas and the thermal flow is driving convection currents creating turbulence and or a heat pumping loop...

Homework Statement I read about Joule's experiment proving the transformation of mechanical work into heat. But say I have a bowl with some water, and I start turning a spoon in it very fast, thus doing work - the water won't get hotter! What am I missing? Homework Equations conservation of...

Homework Statement http://i.imgur.com/jmLqca9.jpg pic of question Homework Equations W = p x dV, Q = dU + W etc The Attempt at a Solution I know what the different stages are, a-b and c-d are isobaric, d-a and b-c are isochoric and I believe the answer to a, the net work done in one cycle...

Hi, I'm currently taking thermodynamics in second year mechanical engineering. I read previous threads on here about good textbooks, and everyone seemed to agree that Cengel's book is really good. Its the book we use in class, but at times I don't think it explains everything as fully as it...

1. The problem statement, all variables and given/know In rural communities where landowners have their own water wells, large tanks are used to store water, which is pressurized by a sealed “air cushion”. Water is pumped intermittently from the well to restore the tank supply when the level is...

How can I prove that the entropy change is intrinsically positive? Given two systems with both of the heat capacities are independent of temperature.

Homework Statement A rigid vessel contains 0.1kg of air initially at 1bar and 20degC. A heat transfer to the gas increases the temperature to 1000degC. What type of process does the gas undergo ? Calculate (i) the initial and final volume of the air (ii) the final pressure (iii) the change in...

Homework Statement I have the following task: Homework EquationsThe Attempt at a Solution I already managed to calculate Delta Um, but how do I calculate Q und W. Can I use the equations for the isothermic expansion for ideal gases, even if this are Van-der-Waals Gases?

Homework Statement a small lump of ice at 0 degrees celsius falls to the Earth's surface. when the hailstone hist the surface, all of the kinetic energy of the hailsotne is transferred to thermal energy in the ice. calculate the minimum speed of the hailstone so that it just melts when it hits...

if we apply the laws of thermodynamics to the universe as the system, and factoring dynamic boundary and dynamic system, how could we define the surroundings as a non-infinite, non zero factor?

Homework Statement In a jet engine, a flow of air at 1000 K, 200 kPa, and 40 m/s enters a nozzle, where the air exits at 500 m/s and 90 kPa. What is the exit temperature, inlet area, and exit area, assuming no heat loss? Homework Equations min = mout = m where m = mass air flow dE/dt cv = Qcv...

Hi guys, So I have a question in a piece of coursework which I seem to have done too simply, its worth 7 marks and I am thinking I've missed something somewhere so was hoping to run it by someone else. 1. Homework Statement A system consists of gas contained in a cylinder fitted...

Homework Statement Air enters a diffuser: The ambient temp at the inlet is 300K. The temp leaving the diffuser is 350K The flow speed of air at the inlet is 400m/s Assumptions: Potential energy = 0 Kinetic energy at the diffuser exit is = 0 Air is an ideal gas Q1: assuming air to be an ideal...

Homework Statement A piston-cylinder device initially contains 0.5 m^3 of helium gas at 150 kPa and 20°C.Helium is now compressed in a poytropic process(Pv^n = constant) to 400 kPa and 140°C. Determine the entropy change of helium and whether this process is reversible, irreversible, or...

Homework Statement A 0.2 m^3 steel container that has a mass of 30 kg is filled with liquid water. Initially both the steel tank and the water are at 50°C. Now heat is transferred, and the entire system (i.e., steel and water) cools to the surrounding air temperature of 25°C. Determine the...

I am really stuck at this question. I tried to get the equation of volume with independent variables P and T, but the equation itself does not give a nice form, and thus I cannot get the derivative of V with respect to P. What should I do?

Why temparature is only dependent on internal energy of something, say an ideal gas.

For part number 5, it says to make sure that each ΔT is positive. Why is this? Couldn't it be a negative? Or does it have to be positive since if it wasn't you would be getting heat going in the wrong direction? Like the one substance would be gaining instead of losing the heat? Which would...

Hey Guys! Anyone able to help out here? I have already happily solved for T2 = 369.91K and m2 = 11.492kg However, for question 2.3, I'm terribly stuck. I'm not even sure what to make my control surface. How can I relate pressure outside the valve with the two thermodynamic states I have...

Hello, I have to work on the relation between the thermodynamics and the information theory on both historical and theoretical aspects. My work will not contain proof. It will contain the most important equations and descriptive paragraphs. I need to talk about the relation between Clausius and...

Homework Statement Starting from rest, two identical boxes are pushed through the same distance. Box A experiences a force F, while box B experience a force 2F. What is true about their final speeds?- The final speed of box A is twice that of box B. - The final speed of box A is equal to that...

I've been asked to find the final temperature of different in an insulated container. A combination of 0.25kg water at 20C, 0.4kg aluminum at 26C, and 0.1kg copper at 100C are combined, and allowed to come to thermal equilibrium. Finding the equilibrium temperature for two substances is...

Homework Statement Q3.1 (a) A pump forces 1m^3 /min of water horizontally from an open well to a closed tank where the pressure is 0.9 Mpa.compute the work the pump must do upon the water in an hour just to force the water into the tank against the pressure.sketch the system upon which the work...

Does anyone know of a thermodynamics tables for reference to recommend me?... It would be preferable in metric system or in both, british and metric. I searched in the past posts and, I didn't find information about this issue. I found this tables on Amazon, but I prefer to hear from your...

Homework Statement A reversible heat engine produces work from the temperature difference that exists between a mass of m = 9 kg of an ideal gas (cv = 716 J/kgK, R = 287 J/kgK) in a rigid container and a heat reservoir at THR = 285 K. The only heat transfer interaction experienced by the...

Thermodynamics question: Why does the internal energy have a lower bound? I tried to explain it using postulates, but cannot get the connection between the postulates. Please do explain it briefly. Thank you.

I am facing some overwhelming doubts while trying to study 'Psychrometrics'.Currently I am bamboozled trying to understand the process of adiabatic saturation of moist air. Some of the textbooks claim that a true adiabatic saturation process proceeds along the line of constant enthalpy of moist...

I've just transferred to a new university where they did certain aspects of thermodynamics in their first year, which is a problem because I didn't do any in my first year at the university I was previously at. I did some bits in high school but not to a very high level, so I understand the...

Is there a mathematical way to show that a dissipative (or general?) dynamical system obeys the laws of thermodynamics? I am looking for books/sites/references, thanks for any reply.

Homework Statement A specific type of ideal gas has a specific heat capacity at constant pressure (cp=cv+R) that is a function of temperature T, such that cp=0.5+876T, where cp has units of J/kg/K and T has units of K. The gas, which is initially at T1 = 294 K and P1 = 1x105 Pa, undergoes a...

I have a thermodynamic question which has been answered by my lecturer in a qualitative rather than a quantitative fashion. The question is: My question is can this be answered in a quantitative fashion? I've been trying to find a way but to no avail. My thought process is such that using...

Homework Statement [/B] Homework Equations Assumptions[/B]: Closed System and Quasi-static. p = 90 + 73,386*V -> V = (p-90)/(73,386) v = V/m Q - W = U2 - U1 mass balance: m = m1 = m2 The Attempt at a Solution At state 1: p1 = 110 kPa V1 = (110-90)/(73,386) = 2.725*10-4 m3 v1 = V1/m1...

I keep getting this question wrong, and I am struggling to understand why this is. Homework Statement Homework Equations F = p*A Ap = π*r2 The Attempt at a Solution Denoting patm as atmospheric force, and p0 as pressure inside the cylinder. Firstly, a force balance on the system. Force UP =...