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6

Actually that's not an impossible task as long as you don't constrain the problem by not allowing energy input to the filter. The problem is the famous Maxwell 's Demon, but in the end you have to pay the demon. His efforts don't come free. The Hilsch tube, originally thought to house the demon fails the challenge as it takes excessive energy to separate hot ...


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Recall two things... First that the 1st law is conservation of energy. Second that temperature is a non-decreasing function of internal energy. So if we take two identical samples of gas and add the same heat $Q$ to each (increasing their internal energies), but allow one to do work $W$ on the surrounding while the other does none, then the sample doing ...


4

Let us take the example of the Hubble primary mirror. It has a diameter of 2.4 m and a mass of 828 kg. It is actually made in a sandwich structure - glass-honeycomb-glass - making it about 30 cm thick (for stiffness) but light. The mirror is coated with an aluminum coating of thickness t = 65 nm, with a 25 nm MgF2 protective coating on top. Coefficient of ...


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Planck published several works on the theory of blackbody radiation based on different ideas, but generally the use of integer counting of energy he meant to be used for the energy of material oscillators. He did not believe the quantization applied to light itself - he assumed Maxwell's theory with its differential equations and derived his spectral ...


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There is also, a gas of photons in the right side. It was trapped there when you assembled your box, and since you are assuming a perfectly zero emissivity, these photons must be perfectly reflected from all surfaces. That means they are blue shifted if the wall moves toward the right and red-shifted if the wall moves toward the left. Result: If you ...


2

Heat if you remember from 8th grade science transfers by convection, conduction and radiation. Convection is by the flow of a fluid which cannot go faster than light, conduction is caused by molecules colliding with neighboring molecules, conductive heat equations are only for after a steady flow has been established and do not treat transient effects so can ...


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I suspect you are looking at the steady state solution of the set of partial differential equations that model heat dynamic heat conduction. The dynamic equations will show that the heat is NOT propagating at an infinite rate. Using the steady state solution to infer dynamic response is not proper.


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For a reversible process, the overall change in entropy is zero (i.e. no entropy is created). However, entropy can be transferred between different systems and the environment through reversible processes. For a system transferring heat/work to/from its environment - as I understand it, for an internally reversible process, no irreversibilities exist within ...


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I know this question is technically already answered, but there were several things missing from the answers that I thought should be mentioned (I am writing a review paper comparing different regions of space so I had these numbers at hand already as well). The speed of sound in space has multiple meanings because space is not a vacuum (though the number ...


1

The bottom of Niagara Falls is in shadow, both because points northward, both for the reflecting fog clouds. Thereafter the rock average temperature is lower there then on top, quickly cooling the fallen water. The experience of ACuriousJim should implies that this effect can be more relevant than the others mentioned above, which just reduce the temperature ...


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I still don't feel it on an intuitive level... When a gas is heated at constant volume,all the heat supplied is used to increase the internal energy of the gas.(since the volume is constant the gas cannot expand so) When a gas is heated at constant pressure ,the gas expands.It does work against the external pressure . The heat is used in two ways ...


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The Landau model for ferromagnetism has the following expression for the free energy density, as a function of temperature $T$ and magnetization $M$: $$F(T,M)=F_0(T)+\dfrac{a}{2}(T-T_C)M^2+\dfrac{b}{4}M^4+\dfrac{c}{6}M^6+\mathcal{O}(M^6)$$ First order phase transition occurs when the first derivative of $F$ (namely, the entropy) is discontinuous as $T\to ...


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What effect [does] heating have on [the electrical conductivity of] metals? Conductivity drops as temperature rises See How Does Temperature Affect the Conductivity of a Conductor? Note, this graph plots resistivity not conductivity, vs temperature. Temperature obviously affects the thermal velocity of free electrons and this affects the rate of ...


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The definitions are equal: Sum of external forces zero, sum of external torques is zero. This comes from classical mechanics. For a perfect ideal fluid, the external force density is the pressure gradient: $\mathbf f = -\nabla p$, and therefore, uniform pressure in a fluid means no external force on it, and then it is in mechanical equilibrium. So, its more ...



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