What is Thermodyamics: Definition and 267 Discussions

Homework Statement Two adiabatic vessels containing ##n## moles of mono atomic and diatomic gas respectively are connected by a rod of length ##l##, cross sectional area ##A## and thermal conductivity ##k##. The surface of the rod is insulated. The initial temperatures of the vessels are...

Homework Statement Two identical brass bars in a chamber with perfect (thermally insulating) vacuum are at respective temperature T hot>T cold. They are brought in contact together so that they touch and make perfect diathermal contact and equilibrate towards a common temperature. We want to...

Homework Statement Homework Equations $$PV^{\gamma}=\mathrm{constant}$$ The Attempt at a Solution Initially, the piston will get a velocity ##v##. But the chamber will move too because of the forces exerted by the gas. Since total external force is zero, velocity of centre of mass is...

I have read that when we directly use 'W' Joules of electrical energy to heat a liquid,the maximum heat we can use to heat the liquid is W. However, when we use a heat pump Q=[COP+1]*W , and that means Q > W. Hence heat pump is more efficient and is preferred over electrical heater. Doesn't this...

http://arxiv.org/ftp/cs/papers/0701/0701016.pdf The above is link of Kafri's paper I was just studying at high school when I found this theoretical scientific discovery proposed by an enough notable Israeli physicist Oded Kafri. He made a unique unification or link between second law of...

Assuming the law of thermodynamics holds true throughout the entirety of the universe, is it theoretically possible to engineer our own stars and solar systems, and would doing so prevent the proposed eventual "Dark Age" of the universe? We understand how stars are formed, so what's stopping us...

I've read in my texts that the there are two kinds of Molar Specific Heat Capacities for gases: 1. Molar Specific Heat Capacity at constant Volume ----- ##C_v## 2. Molar Specific Heat Capacity at constant Pressure ---- ##C_p## And in case of Constant temperature there is no point in...

Homework Statement Two moles of an ideal gas undergo a reversible isothermal expansion from 3.37×10−2m3 to 4.29×10−2m3 at a temperature of 29.6 ∘C. What is the change in entropy ΔS of the gas? Homework Equations pV=nRT The Attempt at a Solution W=∫V2V1pdV, I don't know how to use this...

I came across an equation used in one of the forums from a few years ago. Found here: https://www.physicsforums.com/threads/calculate-how-long-it-will-take-for-the-ice-to-melt.531908/ I am researching a similar topic into melting ice and using it as a cooling solution. However when i came...

Homework Statement Homework Equations Maxwell relations The Attempt at a Solution Here is how I proceeded. Am I allowed to go from line 1 to 2? It almost seems too simple. dU=TdS-PdV \\ (\frac{\partial U}{\partial P})_T=T(\frac{\partial S}{\partial P})_T-P(\frac{\partial V}{\partial P})_T...

Homework Statement Assuming water to be an ideal gas, enthalpy of vaporization is x joules per mole. I have to find change in internal energy an 100 degree Celsius for one mole of water. also find heat absorbed. Homework EquationsThe Attempt at a Solution I initially thought that during...

1. Homework Statement We want to heat up 200 liters of water in a bathtub from 15 ◦C to 30 ◦C. The temperature is increased by adding marble stones to the water. The initial temperature of the marble stones is 773, 15 K. Assume that the marble is rigid, with the heat capacity cm = 0.88 J ·K−1...

Homework Statement Homework Equations Maxwell relations The Attempt at a Solution I have an attempt at a solution, but I am not sure if I can replace the integral of dT in the helmholtz equation by the T I found using the internal energy. Does this make sense? Thanks

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...

[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...

Hi, Consider the conservation laws for an isothermal linear incompressible flow governed by the mass and momentum equation. The kinetic energy equation is then solved to see if energy conserved. Can anyone tell me if once it is shown energy is conserved, it implies that convergence is obtained...

A quantity of coal used in a boiler had the following analysis: 82% C; 5% H; 6% O; 2% N; 5% ash. The dry flue gas analysis showed 14% CO2 and some oxygen. Calculate the oxygen content of the dry flue gas. I have first written the formula for combustion including the variables for balancing the...

Could someone please tell me what the tilde sign stands for in this equation:$$w_{0}\left(e_{ij}\right)=\int s_{ij}d\tilde{e_{ij}}=\frac{1}{2}\,\underline{\underline{s}}:\underline{\underline{e}}$$ where and ##\underline{\underline{e}}## is the Green Lagrangian strain tensor and...

Homework Statement You have 0.50 mol of steam which has been supercooled to 95˚C at 1 atm. Since the steam is below the boiling/condensation point, it proceeds to partially condense into liquid water. This happens in a thermally-insulated vessel at constant pressure. (a) When the system...

We have an ideal gas enclosed in cylinder whose top is covered by a piston of certain weight ##mg##. At this stage, the piston is at rest which means the force by which the gas acts on the piston (##F=PA## where ## P## is the gas pressure and ##A## is the cross sectional area of the cylinder) is...

This P-V diagram summarizes the Carnot cycle. Given a working fluid whose state ##(P,V,T)## is ##(P_1,V_1,T_1)## (at point 1) where ##PV=nRT##, the working fluid undergoes a cycle of four stages and again retrieve its original state of ##(P_1,V_1,T_1)##, that is it gets back again to point 1...

An ideal Carnot engine is composed of two reservoirs and a working fluid. The hot Reservoir and the cold one have temperatures ##T_1## and ##T_2## respectively, with ##T_1>T_2##. The working fluid is in a phase transition and has temperature ##T_1## at the start of the Carnot cycle. It undergoes...

Can anyone recommend any good reading on Maxwell's demon? I'm mostly looking for things at the undergraduate level, but I don't mind something less rigorous or more advanced. (Apologies to the mods if this is in the wrong forum.)

Homework Statement Show that (∂(βA)/∂β)N,V = E, where A = E - TS is the Helmholtz Free Energy and E is the Internal Energy. Homework Equations A = E - TS dE = TdS - pdV + ΣUidni β = 1 / (kBT) The Attempt at a Solution (∂(βA)/∂β)N,V = (∂/∂β) * (βE - βTS) (∂(βA)/∂β)N,V = (∂/∂β) * (βE -...

Suppose that you have N = \left(\frac{\partial U}{\partial \mu}\right)_{S,V} < 0, supposedly the number of particles, even though the actual number of particles is greater than zero. This means that you can have, in a system subjected to a grand canonical ensemble, less than 0 particle for...

The space above the mercury column in a thermometer ordinarily is evacuated, but due to faulty manufacture, a particular thermometer has a pressure of 2 mmHg of air in this space when the whole thermometer is immersed in a bath at 0 degrees Celsius. Calculate the pressure of the air when the...

Homework Statement A rigid vessel of volume 5m^3 contains 1.0 kg of water and steam at 19 degree C.Find the pressure and the mass of liquid and vapour in the vessel. The vessel is now heated unit the water is just evaporated. Calculate the the pressure and temperature of this process. The...

Can someone recommend me some good textbooks or articles that contain or focus on statistical thermodynamics and/or oscillatory motion (preferably with advanced math, not just stories)?

Hello, I'm interested to know if that in a fixed insulated volume (e.g. 500ml), at some temperature (e.g. 293K) and pressure (e.g. 1 atmosphere), and you increase the pressure by a specific amount by pumping more gas (e.g. air at 293K) into the volume can you work out the expected increase in...

For a given closed system that does not experience phase transitions, does its internal energy depend only on its temperature?

There was an equation I saw before and I think it pertains to Boltzmann and thermodynamics. I think it describes the entropy of a system. From what I can remember, it involves the symbol omega to denote micro states, k for a constant, and a logarithm somewhere. Anyways, hopefully some one knows...

I have often visited and read questions and answers, and really like the subject so figured I'd join and participate. Academically, I come from the Arts world (history). What really got me interested was a project I did a few years ago, which was a market study of radioisotopes. I am endlessly...

If we have a cube full of water and glass walls, with an external environmental temperature of 20 degrees celsius, what is the power required to maintain an internal temperature of 25 degrees celsius? Assume sides are 50cm. I don't know what to do, I was trying out the P = (kA/L)(Tf-Ti)...

I read an article a day or so ago titled Hydrostatic Lapse, which makes the case for a phenomenon that I thought was well and truly confirmed; that gravity is responsible for the cooling of air with altitude. However I discover in the sequel article The Gemini Cycle that this phenomenon is...

Homework Statement Understanding the first law of thermodynamics Homework Equations The Attempt at a Solution [/B] I have been doing a self-study course on heat transfer. I have been reading from the book by Incropera and all. I understand that the first law of thermodynamics forms the very...

Homework Statement Adsorption, coagulation, and flocculation are all important processes to remove or separate target substances from mixtures. In these processes, we can observe the spontaneous decrease of entropy.; can we therefore conclude that the second law of thermodynamics doesn't always...

From a video lecture, it is mentioned that "dU≠dW in Joule's free expansion if the process is irreversible and adiabatic" Mentioned in around 36:00-38:00 in the video: What I would like to ask is why in this irreversible adiabatic process, dU≠dW? Is it because the W here doesn't include other...

A rectangular (simplified) container with rigid surfaces, has a certain mass of ideal gas within it, and it accelerates in free space, undergoing rectilinear motion. There are no dissipative forces. Now, since the container moves, its kinetic energy increases, and since the temperature of the...

Homework Statement Try to estimate the latent heat of vaporization of water and nitrogen using the Van der Waals model. What happens? Homework Equations $$\Delta Q = T\Delta S=L$$ $$S=nR\left[ \ln\left(\frac{(V-nb)T^{3/2}}{n\Phi}\right)+\frac{5}{2} \right]$$ The Attempt at a Solution I...

Hello all! Can you please provide some guidance with this problem? 1. Homework Statement Calculate the air pressure at 3000m above sea level assuming that the molecular weight of air is 29 and the ambient temperature is constant against height. Homework Equations Stokes-Einstein equation. In...

Ok, I've built a numerical model to show the cooling of hot magma sills entered into the crust over time. The results show that the volume of the "hot" zone when the emplacement of a constant volume of hot sills is all done will vary as a matter of two things: the overall rate at which the magma...

In a reservoir of a well type manometer, the sealing liquid is mercury having a weight density of 132.5 KN/m^3. If the area of the well is 0.02m^2 and that of the tube is 40mm^2. Calculate the height of the measuring column if the applied differential pressure is 70KN/m^2. Relevant formulae...

Homework Statement [/B] A molten metal is forced through a cylindrical die at a pressure of 168000 Kg per square meter. Given that the density of the molten metal is 2000 Kg per cubic meter and the specific heat of the metal is 0.03, find the rise in temperature during...

Homework Statement Assume that you heat your home with a heat pump whose heat exchanger is at Tc=2∘C, and which maintains the baseboard radiators at Th=47∘C. If it would cost $1000 to heat the house for one winter with ideal electric heaters (which have a coefficient of performance of 1), how...

I've started using LaTeX to take notes on Donald Fitts' Nonequilibrium Thermodynamics. After I finish, I intend to use other resources to add more to it. Fitts' book focuses on classical fluid nonequilibrium thermodynamics (i.e. doesn't use statistical mechanics but instead uses continuum...

1. Ideal gas cycle - diesel engine cycle. You begin at some volume V1. Perform an adiabatic compression to V2. Perform an expansion to V3 at constant pressure. Next, perform an adiabatic expansion to V4, Last, it moves back to V1 at a fixed volume, while decreasing temperature back to...

Hello all, I'm stuck with following problem: At our plant we have a tank filled with a liquid maintained on 80°C with a steam coil. During the night the steam is switched off and the liquid temperature start to drop. Tank mass not taken into account atm. mass liquid: 20000 kg cp liquid...

While reading some articles on Wikipedia I came upon one interesting statement that essential says (I've rephrased for clarity; correct me if I'm wrong): "The Time-asymmetry of the second law of thermodynamics is due to the initial conditions of our universe" Can someone elaborate on what...

When reading some material concerning Ginzburg-Landau theory of superconductors, I got the following sentence: The appropriate thermodynamic potential for describing a superconductor in an applied magnetic field is the Gibbs free energy ##G## (natural variable ##H##) and not the Helmholtz free...

Hi! I'd appreciate some help solving the thermodynamic's problem. I am sorry if the problem statement isn't 100% clear, as I've translated it from my native language. I'd really like if you could help me check my equations/procedure/results. In the following link both my attempted solutions...