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Wikipedia has a good article on hybrid photovoltaic-thermal systems. As you proposed they consist of a solar cell with a thermal collector at the rear. Solar energy conversion is a fascinating topic from a thermodynamic perspective and has been summarised beautifully by the work of De Vos, The Thermodynamics of Solar Energy Conversion, ISBN: ...


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Light like sunlight is an electromagnetic wave with components with different frequencies. These components follow a particular distribution of intensities. One portion of the energy of this light resides in what is called infrared radiation and most materials absorb in that range (link provides some more extra information regarding this radiation and heat). ...


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There are several possible approaches to this question, but I've always been a fan of the one taken by Edwin Jaynes in his 1965 paper Gibbs vs Boltzmann Entropies. (See sections V and VI for the discussion, which I think can be read in isolation from the rest of the paper.) Here he derives the second law from the empirical fact that we as scientists and ...


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For gravitational systems one has to be careful making statements about entropy and the second law of thermodynamics. Your example is similar to the gravitational collapse of a gas cloud if you think carefully about it. In that case and in yours, the shrinking of the gas will raise it's heat. Now even though the increase of entropy due to the increased ...


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Stefano Bordoni's 2012 Taming Complexity (e-book from ResearchGate; review) is a good place to start.(Bordoni has a master's degree in physics and three PhDs, in the history of science, anthropology and epistemology of complexity, and philosophy.) Bordoni refers to Brush's 1986 The Kind of Motion We Call Heat: A History of the Kinetic Theory of Gases in ...


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At constant pressure the volume of an ideal gas is given by Charles' law: $$ V \propto T $$ and this law tells us that when the temperature $T$ falls to zero the volume $V$ also becomes zero. But no gas is ideal and real gases show all sorts of non-ideal behaviour. For example real gases liquify then solidify as the temperatue falls. Real gases deviate ...


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The filament will be a reasonable approximation to a black body emitter, so it's spectrum will be given by Planck's law: $$ B = \frac{2hc^2}{\lambda^5} \frac{1}{e^{\frac{hc}{k\lambda T}} - 1} $$ So just measure the radiance of the light from the filament for a range of wavelengths and do a fit to Planck's law by varying $T$. This will give you an excellent ...


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The one that absorbs more heat from you will cool you more, and seem colder. But it isn't entirely straightforward. If you pour water in your hand, water will flow to fit you. An ice cube will not make as good contact. Water in contact with you will warm. It can then flow away and be replaced by fresh cold water. Ice doesn't flow On the other hand, Ice ...


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Consider a container containing n moles of an ideal gas. The gas exerts a pressure P on the container and the piston. If P equals the atmospheric pressure, then the piston does not move, as it experiences equal forces from in and out of the container. When you increase the external pressure, the gas in the container is compressed. If the compression of the ...


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How's this for simple and intuitive? A gas is separate particles moving around at great distances from each other. As you compress the gas, the particles get closer together. The particles of a liquid are in contact with each other, but as you heat it, there is more and more space between them as they zip and jiggle more and more. The combination of heat ...


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You really are asking two questions. First - how do we calculate the temperature: At the typical temperatures of a halogen bulb, the large majority of heat loss is due to thermal radiation (although there is some conductive loss in a halogen bulb as the bulb is not evacuated). Because of this, the most important factor is the "apparent size" of the ...


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The answer lies in probability theory. Roughly, the probability of an event or macro state $A$ to happen is the number of instances $\Omega(A)$ in which it is fulfilled divided by the total number of possible instances or micro states $\Omega$ i.e. $p(A) = \frac{\Omega(A)}{\Omega}$. So the reason why you want to maximize $\Omega(A)$ is because you seek ...


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response function = susceptibility = (pure or mixed) second derivative of a (Helmholtz, Gibbs, etc.) free energy. Magnetization is not a response function as the free energy is not observable, so one cannot observe the response to a change of some variable.


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The distribution of speeds in an ideal gas is given by the Maxwell-Boltzmann distribution. There are a variety of average speeds e.g. the most probable speed, the mean speed and the root mean square speed. Which one you use will depend on the application. The two equations you give are for the RMS speed: $$ \sqrt{\langle v^2 \rangle} = \sqrt{\frac{3kT}{m}} ...


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As a physics problem in a textbook, you could get somewhat close. Both the water and the steel have a heat capacity that relates the amount of temperature rise that would accompany an input of energy. If you make a few assumptions, you can relate the two. The problem with a real-world application is that those assumptions may be far from valid. The two ...


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Q=mc(t1-t2) You need to calculate C, the specific heat capacity of Earth(as a whole). You need to calculate the specific heat capacity of everything present on, inside earth for that purpose. It might be possible after we advance a bit more further:).


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Global energy consumption is $5\times10^{20}\ J/yr$ Assume it is all used to power incandescent lightbulbs, so 95% goes to heating the atmosphere The mass of the atmosphere is $5\times10^{18}\ kg$ The heat capacity of air is $1\times10^{3}\frac{J}{kg\cdot °C}$ Assuming all the heat goes to the atmosphere and stays there, using the definition of heat ...


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The very famous Newton-Laplace equation is a relation between the speed of sound and the pressure of an ideal gas. It can be written as: $$ v = \sqrt{\gamma P / \rho} $$ where v is the velocity of sound in the given medium, P is the pressure, γ is the ratio of the heat capacities for the medium and ρ is the density of the medium. The Newton-Laplace was ...


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What's true is that it's law of conservation of energy. It particularly states: Q= Del(U) + W, U: internal energy. That is, the total energy given to a system does two things, first it makes the system do the desired useful work and second it changes the internal energy of the system. The work can be positive or negative according to W=q(dv). Example: ...


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I suggest to compare human produced heat with the incident heat of the sun which is around 1 kW/m$^2$. The usual comparison is "the sun delivers more heat in an hour than humans use in a day". While such a comparison may not remain accurate forever, a difference in scale of 7000x suggests that even if humans doubled thei energy consumption every 17 years ...


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Adiabatic process would mean no heat transfer between the surrounding and the system. Irreversiblility would mean entropy definitely changed after the process. Let's say, entropy increased (which is obviously natural) after the process. The increase in entropy of the system is because its volume is suddenly increased (and so did the disorder and ...


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IMHO it's important to look hard at the ontology of what's actually there and take care to distinguish between reality and abstraction. For example: I was reading about the light cone in relativity... Relativity is just about the best-tested theory we've got. I "root for relativity". But I will say this: a light cone is an abstract thing. You cannot point ...


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What you are asking is potentially very dangerous - but it is also what happens inside many cars in the carburetor - this is really an engineering / chemical engineering problem and if you are serious about doing this you might want to look up the linked wikipedia page about carburetors. Hope this is useful


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The air in the freezer is a poor conductor of heat. The greater surface area of the porous paper along with its heat conducting water allows it to act as a heat sinc. It transfers heat from the liquid to the glass or aluminium and then to the water in the paper which sheds the energy by conducting it to the surrounding materials such as the air and the ...


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Roughly, the system that you are imagining is a nuclear fusion-fission hybrid, except for the fact that it is supposed to work in the exact opposite manner as compared to what you have imagined - the tokamak is not powered by a fission bomb here. The basic idea behind the proposal goes as follows: Nuclear fission is known to be a popular alternative ...


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There is a model described in Main's Vibrations and Waves in Physics dealing with the speed of sound variations you might consider useful. Sorry, I would just comment that, but I don't have enough reputation. The other way might be to derive the speed of sound not from the ideal gas laws but from van der Waals equation, but to be honest, I've never tried ...


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So the first law for an system where we don't have mass flows in or out ( a closed system ), is $\Delta Q + \Delta W = \Delta U$ Where $Q$ is your net heat added, and $W$ is your net work added, and $U$ is your net internal energy change: internal energy being like the sum of all the different kinetic energies of the molecules. This is why when we add ...


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Water forms close to perfect spheres in zero gravity due to it's surface tension. There's a variety of videos of water in the space station. Ice, assuming you start with one of those balls of water, you have to ask first, would it freeze outside in (say, the temperature of the station is dropped below 0 C), or would it freeze inside-out, say you stick a ...



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