What is Thermodyamics: Definition and 267 Discussions

How does the minimum(coldest) temperature that a supercooled solution of ethanol and distilled water depend on the concentration?

There is some ideal gas in a container moving with some velocity on a smooth surface and you suddenly stop it( say by using your hands) , will the temperature of the gas increase? It seems to me that since you're suddenly stopping it there is no work done (because of no displacement ) so the...

Hi, When a hot and dense fluid suddenly expands, how much can it cool down. Lets take for example an expansion valve from an AC, does the fluid do work when passing through the valve or does it not even need to do work in order to cool down. What is the lowest temperature that the fluid can...

Hello everyone: Here is the problem: Under thermal equilibrium, photon's number can be described as the photonic density of state (PDOS) * occupation number(ON). Also, the photon's flux can be described as PDOS * ON * effective particle velocity into certain direction ( V) The occupation...

In deriving thermodynamic temperature scale, it uses the concept that heat transfer between two reservoirs is the function of the reservoirs' temperatures. i.e. Q1/Q2=Φ(T1,T2). And then further express that Φ(T1,T2)=ψ(T1)/ψ(T2). I have two questions, 1. Is it a hidden assumption that the...

I am confused about the following; where am I going wrong here? 1. (1/2)kT is defined as the average kinetic energy of the molecules of a substance at temperature T, right? 2. You can derive the Boltzmann distribution/Boltzmann factors using (1/2)kT as the kinetic energy, making an argument...

For an ideal gas, the internal energy is a function only of temperature, so that dU = CvdT can always be applied. I am not sure whether dH=CP dT is also always true even the pressure is not constant.

We know that one model for ideal gas is monoatomic gas with no attractive force between atoms, elastic collision and some other assumptions. I would like to ask if there exist a gas behave exactly the same but the only difference is it's a diatomic gas (or more complicated structure), should it...

Homework Statement T1= 20C T2=80C Power=2kW Volume= 10liters Homework Equations Q= Power x time Q= m x c x DELTA Temp The Attempt at a Solution Do I need another equation to be able to find the heat? Since I have the equation of the heat I have the mass and I have the temperature but the c I...

Homework Statement A thin-walled cylinder of mass m is filled with monatomic ideal gas and is lying on a horizontal frictionless surface. The initial internal energy of gas is U = cT. There is a thin insulating piston in the middle of the cylinder of mass M. The piston and the cylinder are...

Hello everybody, I am working on some tests on materials and structures in a vacuum chamber. I noted that during the final moments of the pressure rising (when I open the valve to let the air in), temperature sensors installed in the chamber record the temperature rising more than ten degrees...

Some books say when heat flows into a monatomic gas at constant volume, all of the added energy goes into an increase in random translational molecular kinetic energy. But when the temperature is increased by the same amount in a diatomic or polyatomic gas, additional heat is needed to supply...

Homework Statement Given dE=TdS-PdV+\mu dN, PV=NT and Cv=\frac{3}{2}N Find E Homework Equations dE=TdS-PdV+\mu dN, PV=NT and Cv=\frac{3}{2}N The Attempt at a Solution That part that is confusing me is the chemical potential, not sure what to do with it. Finding the energy for the ideal...

( part a only I don't understand how you know from this question that it is a constant pressure process. I thought it is a polytropic process. So it will have a pVγ curve. I was drawing a pV curve. The answer is a straight line parallel to x- axis. My question: How do I know from...

Homework Statement If you mixed 0.2kg of ice that is at -5 degrees C with 0.02kg of water that is at 15 degrees C, what will be the temperature and condition of the final state once equilibrium is achieved? Homework Equations Q=mL Q=mc(delta T)The Attempt at a Solution After setting up a heat...

Hi everyone! I am a UK grad student working in acoustics. My own background is in EE, so i am largely self taught in thermodynamics. Consequently id really appreciate any insight any of you real physicists can give me with my problem! Following derivations in books i can derive the enthalpy...

Homework Statement Two identical balls, A and B, of uniform composition and initially at the same temperature, each absorb exactly the same amount of heat. A is hanging down from the ceiling while B rests on the horizontal floor in the same room. Assuming no subsequent heat loss by the...