Thermodynamics Definition and 1000 Threads

Homework Statement Consider a rigid piston cylinder arrangement. Assume that the cylinder and the piston are covered by a perfectly insulating material and the piston cylinder interface is very smooth. Two types of ideal gases are separated in the cylinder by the piston. The number of gas...

GUT's violate baryon number b/c baryon conservation is an emergent phenomenon second law of thermodynamics clearly applies to macroscopic systems, and are the result of the many ways in which atoms of macroscopic systems can be arranged. what if second law of thermodynamics though is just...

Guys I am getting confused that what is state function? People say if state changes then state function also changes. But my view is if that variable changes then only state changes and its not necessary when a state change will always lead to change of every state function.

Hi All, I have a little query concerning the derivation of PV γ = constant. In my textbook of Physics, first they give the equation for adiabatic process using the first law of Thermodynamics, as; dEint = W → (1) where, ΔEint ⇒ change in internal energy and W ⇒ workdone Then, they used...

Homework Statement Exercise 4 in the upload titled Dok1.pdf. Write down an expression for the canonical partition function for N ideal Na2 gas molecules, when the rotational contribution is treated classically, and all inner degrees of freedom are treated quantum mechanically. Use this and...

Hawking showed that black holes dissipate energy when virtual particles are "emitted" by black holes and therefore black holes evaporate. However it seems to me that a shrinking black hole means a decrease in entropy and thus a violation of the second law of thermodynamics; is this the case?

Hi all, It seems I haven't completely grasped the use of Partial Derivatives in general; I have seen many discussions here dealing broadly with the same topic, but can't find the answer to my doubt. So, any help would be most welcome: In Pathria's book (3rd ed.), equation (1.3.11) says: P =...

Homework Statement A pure substance is placed into two containers of the same volume. Container 1 has twice the mass of pure substance of Container 2. After the containers are shut and both reach thermal equilibrium with the surroundings, what do we know about: a) the pressure of Container 1...

My question is: according to Carnot cycle, the maximum efficiency of a heat engine is given by 1 - T2/T1, where T2 is the temperature of the cold source and T1 the temperature of the hot source. So, accordingly, as higher T2 is for a same T1, lowest is the efficiency of the engine. But, the...

Hi guys, i just discovered this forum and this is my first post so apologies if i made any mistake with the how I am suppose to structure a thread. but nontheless any help would be greatly appreciated! cheers 1. Homework Statement 4. A 250mm diameter insulated cylinder (see figure below) is...

Hi everyone, I have been looking at Carnot heat engines in a bid to better understand entropy, and I can't figure out how it actually does work. Why does the piston move? In some diagrams I have seen weights being removed from the piston, reducing the pressure at constant temperature and...

In Principles of General Thermodynamics, Hatsopoulus and Keenan (p 442) make the following claim: What, however, would be some physical examples of such a system?

What is the role of Quantum Mechanics and Thermodynamics in solar cell operation? Is quantum mechanics the photovolatic effect, and thermodynamics the cell efficiency?

I'm currently reading thermodynamics which is only the second volume of all the physics course that I'm planning to read. So for the math in it is just killing me literally. Mechanics was relatively easy but this subject is just too freaking hard. All these partial differential equations and...

Hi! I'm a junior in high school studying for the IPhO and I've started learning thermodynamics as part of my preparation. I have a guide to the exam that says things like this will be tested: Carnot engine Kirchhoff's law Wien's law Stefan's law Stefan-Boltzmann law Newton's law of cooling...

Homework Statement Show that (du/dv)T = T(dp/dt)v - p Homework Equations Using Tds = du + pdv and a Maxwell relation The Attempt at a Solution I've solved the problem, but I'm not entirely sure my method is correct. Tds = du + pdv ---> du = Tds - Pdv - Using dF=(dF/dx)ydx +(dF/dy)xdy...

What I know: Below link is about Torricelli's law. Velocity of liquid coming out of bottom of the tank i.e comes after using Bernoulli's equation square root of (2*g*h*) where "h" is height of fluid in the container and "g" is acceleration due to gravity...

I guess there would be no flow in case 2; case 3 seems easy to me applying fluid mechanics principle; flow will be 1 to 2. But I doubt case 1; it is not in thermal equilibrium ? Pls help

Hi all, I'm working through a derivation of the general relationship between Cp and Cv and there's one point which is confusing me. I understand that and and that this implies the following: but isn't this equal to 0? Shouldn't the two partial derivatives on the right...

Why is is true that for a given system, if I fix the volume and increase the temperature, you'd expect the occupancy of the energy levels to change, but not the levels themselves? Can I think of this in terms of the fact that the boundary conditions for the solution of the TISE are fixed, such...

Homework Statement Please see the attached image Homework Equations pv=nRTThe Attempt at a Solution i don't know how to calculate the work done by the gas in the question and i calculated the change in internal energy.

NO TEMPLATE---MISPLACED HOMEWORK So it seems like a pretty simple question, and in all likelihood it is, but my lecturer somehow managed to miss this bit in his lecture notes. A heat engine operates between 500K and 300K with 20% of the efficiency of Carnot engine operating between the same...

Homework Statement A 10.0 g sample of solid platinum is placed in a large, sealed vessel at a sufficiently low pressure that the platinum is able to sublimate directly to a gas. Some thermodynamic properties of platinum at low pressure are given in the following table. Molar mass, M - 195...

Homework Statement two cubic ft, of air at 85 f and 13.9 psi, compress to 115 psi. What is the final temp, the work, the internal energy "delta u", and Q Homework Equations well i don't have any equations, i am asking for the equations The Attempt at a Solution i don't know how to approach to...

Homework Statement Hello, new here! I have a question regarding reversible or irreversible expansions in regards to figuring which equation is needed to figure out work, W. For starters, here is the question: One mole of an ideal monatomic gas is expanded from an initial state of 3 atm and 500...

Homework Statement A 3.20 g lead bullet at 28.0°C is fired at a speed of 210 m/s into a large block of ice at 0°C, in which it becomes embedded. What mass of ice melts (g)? Homework Equations I thought that the KE of the bullet would be transferred into heatThe Attempt at a Solution I used...

Homework Statement Steam, at 15 bar and 280oC, enters a nozzle with an initial velocity of 125 m/s. The steam enthalpy at the exit section is 2800 kJ/kg and the heat loss is 25 kJ/kg. What is the exit steam velocity?. Homework Equations 1)Qin - Qout = m [h2-h1+((c22-c12))/2] 2)h = Pv + u...

Homework Statement I.The gas is heated at constant pressure until the volume is 4.4L at point B II. The gas is cooled at constant volume until the pressure decreases to 1.2 atm III. The gas undergoes an isothermal compression back to point A a) Find the temperature at Point A,B,C b) Find the...

Homework Statement You add 50 g of steam at 150 degrees centigrade to 50 g of ice at negative five degrees centigrade. What is the final temperature? Homework Equations Q = mLfv Q = mcΔT The Attempt at a Solution Qg = Ql Q1 + Q2 = -Q3 - Q4 mLf + mcΔT = -mLv + mcΔT [ΔT will be negative, making...

When I leave a closed half full bottle of water overnight, the next morning I find condensation on the inside walls of the bottle BUT! Only where sun light has reached it! I thought this was widely known and easy to explain, but I've been looking on the Internet for a while and haven't found a...

Homework Statement [/B] An insulated cylinder containing water has a piston held by a pin. The water is initially saturated vapour at 65°C and a volume of 5L. The piston has a total mass of 10kg, its area is 0.003 m^2 and the atmospheric pressure is 100kPa. The pin is then released, allowing...

The thermal efficiency of a reversible heat engine is solely a function of the temperature of the two reservoirs. η = f(θH,θC) = 1 - (QC/QH) (QC/QH) = 1 - f(θH,θC) (QC/QH) = Ψ(θH,θC) The simplest function that can be used is T1/T2 (QC/QH) = T1/T2 In order to define the Kelvin scale we assign a...

Homework Statement Freezing of water at 273 K and 1 atm which of the following is true for the above thermodynamics process p) q=0 q)w=0 r)ΔSsys<0 s)ΔU=0 t)ΔG=0 Homework Equations none[/B]The Attempt at a Solution [/B] i got r, s ,t since the reaction happens at constant...

Homework Statement A 10 L truck engine has a volumetric efficiency of 100%. It has a turbocharger which increased the mass flow of air and its pressure by a factor of 2 when the engine is running at 4300 rpm. Find the turbocharger rpm, efficiency, and the temperature of the air leaving the...

qrev/T = ΔS here what does ΔS signify?does it mean change in entropy of system or surroundings? how is entropy of system,surrounding and universe related to each other and which entropy is used in gibbs free energy equation?

Hello I am confused with the energy conservation equation in thermodynamics. Is it U2 - U1 = Q - W ? This is what most books say. Or is it H2 - H1 = Q - W ? Which should I use to solve problems? For example we have a gas with U1 and P1V1 (which makes H1). After a process, we have Q...

I have heard (read) much debate over the fundamental problems with white holes, mainly that they violate Thermodynamics by increasing entropy. However, I have also read that a black hole bends space-time enough to "connect" somewhere else as an Einstein-Rosen Bridge. So if the exact same event...

Homework Statement Suppose you walk into a sauna that has an ambient temperature of 57.0°C. Calculate the rate of heat transfer to you by radiation given your skin temperature is 37.0°C, the emissivity of skin is 0.95, and the surface area of your body is 1.60 m2. I solved this first part and...

Too much confusion in my head about these concepts... Is every reversible process quasi static? If not, what are some examples? If process is irreversible then it doesn't need to be non quasi-static, I understand that. (eg. free expansion of the gas) Can irreversible process be quasi static...

For a system modelling a soap bubble, the differential work done is now given by: dW = −pdV + γdA, where γ is the surface tension and A the area. Compute new differential expressions for the potentials U, H, F, G. What are the new natural variables in each case? Are there any new Maxwell...

A one-dimensional polymer molecule (rubber) is chain of N links of the same length a, the links can go either forward or backward but always stay parallel to the x axis. If one denotes the coordinates of the joints are ${x_0, x_1, . . . , x_N}$ , then $|x_n − x_{n+1}| = a$. The energy of the...

If I have a closed system where mass is conserved, what constraint will this bring on the system in terms of infinitesimal quantities. What conclusions can I then draw about the phases at this kind of equilibrium? Suppose we had an isovolumic, isothermal change, how would I have to alter my...

Hi! I'm new to the forums, so I apologize in advance if I'm posting my question in the wrong section. I'm studying thermodynamics right now, and I came across this sentence from my book: Homework Statement "When energy is added to a system and there is no change in the kinetic or potential...

Homework Statement I'm doing a class on thermodynamics and energy and well there's this chapter about pure substances and subcooled liquids, saturated liquids, superheated, etc. stuff like that. The chapter begins by showing a piston-cylinder in an initial state containing liquid water and a...

Let's consider two spherical blackbodies at two foci inside an ellipsoidal heat-reflecting shell. Consider the situation that they both have different radii and that their temperatures are such that they emit the same power. Thus, the surface power flux density of each is inversely proportional...

Homework Statement 1. A gas expands as shown in the graph. If the heat taken in during this process is 1.02 × 10^6 J, the change in internal energy of the gas (in J) is 2. One mole of an ideal gas is held at a constant pressure of 1 atm. Find the change in volume if the temperature changes by...

Homework Statement Two kilograms of air at 5 bar, 350 K, and 5 kg of carbon monoxide, initially at 4 bar, 450 K, are confined to opposite sides of a rigid, well-insulated container by a partition. The partition is free to move and allows conduction from one gas to the other without energy...

Homework Statement How do we obtain: w = q - Δh Homework Equations The Attempt at a Solution If you neglect the second half of the SFEE and simplify we get: What is the next step from the last line in the above image to w = q - Δh I mean dw/dt = dq/dt - Δh so if we multiply by dt we...

Homework Statement I have a question regarding heat engines that cropped up whilst I was doing a practice question. I will summarise the results I obtained for the previous parts of the question so as to save your time. The highlighted parts of the image are where I am having some issues. I...

How would I calculate the rate that water would boil off? I've done a lot of looking into and found an equation but it doesn't seem quite right. What I found states that the KJ/h delivered to the water divided by the latent heat energy gives you the amount of water that will boil off. I tried...