question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
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<p>I'm currently doing some calculations which require evaluating various standard thermal expectation values in the canonical ensemble (both bosons and fermions). Now, in order to make my theoretical machinations easier, I am actually using the grand canonical ensemble, where the chemical potential acts as a Lagrange ... | g13506 | [
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<p>In thermodynamics, the heat $Q$ is defined as a type of energy in transfer, and is not a state function, which function denotes the energy of thermal motion within a system?</p>
<p>1) $TS$, (there is a contradictory, for an idea gas, $dU=TdS-pdV=C_vdT$)</p>
<p>2) Enthalpy $H$, ($H=U-Yx+pV =TS+pV+\sum_j\mu_jN_j$)</... | g13507 | [
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<p>My question is related to simulation of racing ball demonstration.
<a href="http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=142" rel="nofollow">http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=142</a></p>
<p>One ball goes on a straight path, while another one goes on a curved path. On the simulation the seco... | g13508 | [
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<p>This question follows a previous one of mine: <a href="http://physics.stackexchange.com/questions/70707/">Adiabatic theorem and Berry phase</a>. </p>
<p>In his original paper [ M. V. Berry, <a href="http://www.jstor.org/stable/2397741" rel="nofollow">Proc. R. Soc. Lond. A. Math. Phys. Sci. 392, 45 (1984)</a> ], Ber... | g13509 | [
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<p>A plane mirror image approaches the object at the same rate the object approaches the mirror. So the speed of approach is twice the speed at which the object approaches the mirror. If the object approaches the mirror at a speed greater than half the speed of light (c), does that mean that the speed of approach bet... | g13510 | [
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<p>I'm sure a simple question.</p>
<p>I have a video of me jumping off a cliff into a river. I want to calculate how high it is. I know my weight, acceleration due to gravity of course, and I can get the time it took to hit the water.</p>
<p>Can I calculate (albeit roughly) how high the cliff was?</p>
<p>Cheers,</... | g13511 | [
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<p>Do we take gravity = 9.8 m/s² for all heights when solving problems?</p> | g13512 | [
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<p>How can the <a href="https://en.wikipedia.org/wiki/Hanbury_Brown_and_Twiss_effect" rel="nofollow">Hanbury Brown and Twiss effect</a> (photon bunching) be explained if photons don't interact in free space?</p>
<p>To explain it with the influence of the two photons on the two detectors simultaneously would seem stran... | g13513 | [
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<p>I have recently taken an interest in shadows. I know that in order for a shadow to exist that you must have a solid in the way of the light. My hypothesis is that there can be a light so strong, like a laser beam, that it acts like a solid in the sense where it doesn't let light pass through... is this plausible? </... | g13514 | [
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<p>I have a couple of conceptual questions regarding the thermodynamics of scattering. Any partial answer or argument will be appreciated.</p>
<p>For the sake of discussion, consider the scattering of electromagnetic waves. I understand that the physics would be different for other particles or fields, feel free to ba... | g13515 | [
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<p>After moving onto some of the practice textbook exercises in the section covering Kirchhoff's current law and Ohm's law, I came across a problem which evades my best attempts at solving it.</p>
<p><img src="http://i.stack.imgur.com/KybEy.png" alt="problem text"></p>
<p><img src="http://i.stack.imgur.com/goNxE.png"... | g13516 | [
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<p>I have two doubts:
Exactly when does this happen?
and
If we are in a superposition of states (lets say E1 and E2) and the particle absorbs a photon, what will happen? If E3-E1 = hf, will it go to E3?</p>
<p>Thanks!</p> | g13517 | [
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<p>...And you jumped in.</p>
<p>What would happen when you got to the middle of the Earth? Would you gradually slow down, until you got to the middle and once you were in middle would every direction feel like it was up? </p> | g76 | [
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<p>I saw this question in a test. I would have answered kinectic energy due to rotation and translation. It that correct. Else what is the answer?</p>
<p>Oh no, i forgot to mention it was objective type question.There were three other options.I just looked them up</p>
<p>1)kinetic energy due to rotation
2)kinetic en... | g13518 | [
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<p>According to <a href="http://en.wikipedia.org/wiki/Water_rocket#World_record" rel="nofollow">this page</a>, the current record for greatest altitude achieved by a water and air propelled rocket is 2044 feet (623 meters).<br>
In this connection, i had one question: How the greatest altitude depends of the density of... | g13519 | [
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<p>What is the meaning of expansion, shear and viscosity in context of universe? How can we conclude a result after getting a numerical value of above terms?</p> | g13520 | [
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<p>If I have a strong vessel that I've cooled to say -20°C, and lowered the pressure below 0.006 atmospheres, the water in food placed inside will sublimate and freeze dry the food.</p>
<p>But what happens to the water vapor? Does the moisture rise to the top or fall to the bottom of the vessel itself? Or does it jus... | g13521 | [
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<p>I currently make my living as an electrophysicist, so am a bit embarassed at having not thought this one through, before.</p>
<p>Magnetically, the North pole is.... North. We get out our compass, and wait for the North-seeking needle to line up. I've always thought of this end of the needle as the north end.</p>
... | g13522 | [
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<p>I'm aware of Sidney Coleman's 1975/76 sequence of <a href="http://www.physics.harvard.edu/about/Phys253.html">54 lectures</a> on Quantum Field Theory. Are there any other high-quality QFT lecture series available online?</p> | g371 | [
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<p>Given a DeSitter-space metric from the line element:</p>
<p>$$ ds^2=\left(1-\frac{r^2}{R^2}\right)dt^2-\left(1-\frac{r^2}{R^2}\right)^{-1}dr^2-r^2d\Omega^2 $$</p>
<p>Where $R=\sqrt{\frac{3}{\Lambda}}$, and $\Lambda$ is a positive cosmological constant, I am trying to derive the equations for radial null geodesics.... | g13523 | [
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<p>The speed of light is the same in all frames of reference. But imagine a scenario in which you passed by a ship which had (B=.78), while your ship had (B=.94). While somehow being able to look through the window of the ship you were passing, you see someone pointing a green laser into a fish tank, and of course the ... | g13524 | [
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<p>For a given scalar potential $V$, it is known that the corresponding force field $\mathbf{F}$ can be computed from </p>
<p>$$
\mathbf{F} = -\nabla V
$$</p>
<p>Suppose a rigid body is placed inside this potential. The torque on the body $\mathbf{T}$ exerted by the scalar field will be</p>
<p>$$
\begin{align}
\mat... | g13525 | [
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<p>Will it be possible to fry eggs in <a href="http://en.wikipedia.org/wiki/Sahara_Desert_%28ecoregion%29" rel="nofollow">Sahara desert</a> by just keeping them under the sun? If so, then will the radiated eggs be any different? Or will we have to use the <a href="https://en.wikipedia.org/wiki/Solar_cooker" rel="nofoll... | g13526 | [
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<p>I am currently trying to establish a clear picture of pure/mixed/entangled/separable/superposed states. In the following I will always assume a basis of $|1\rangle$ and $|0\rangle$ for my quantum systems. This is what I have so far:</p>
<ul>
<li>superposed: A superposition of two states which a system $A$ can occup... | g13527 | [
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<p>How occurs the <a href="http://en.wikipedia.org/wiki/Chirality_%28mathematics%29" rel="nofollow">enantiomorph</a> of the mirror?</p>
<p>I would like to know how occurs the RELATIONS OF THE RAYS with the mirror and the image, everything that happens to be flipped image from the right to the left.</p> | g421 | [
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<p>A curiosity question.</p>
<p><a href="http://en.wikipedia.org/wiki/Radio_propagation" rel="nofollow">Radio Propagation</a> within Earth's atmosphere is via atmosphere. Broadly speaking a signal loses strength between bouncing off the ionized layer, and absorption by various earthy elements.</p>
<p>If an identical ... | g13528 | [
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<p>The problem description for the <a href="http://en.wikipedia.org/wiki/Yang%E2%80%93Mills_existence_and_mass_gap" rel="nofollow">Yang-Mills Existence and Mass Gap</a> problem (<a href="http://www.claymath.org/sites/default/files/yangmills.pdf" rel="nofollow">http://www.claymath.org/sites/default/files/yangmills.pdf</... | g13529 | [
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<p>I'm a programmer and a game developer, not a mathematician or a physicist. So please go easy on the math :)</p>
<p>I know two things:</p>
<ul>
<li>How to find the new velocities of two objects after an <a href="http://en.wikipedia.org/wiki/Elastic_collision">elastic collision</a>.</li>
<li>How to find the velocity... | g13530 | [
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<p>Consider an acoustic wave in some medium, expressed as particle displacement:</p>
<p>$$s(t,x) = e^{j(-\omega t + kx)} $$</p>
<p>I understand that pressure must be at its maximum when the particle displacement is zero and vice versa. But there are many functions that satisfy that criterion.</p>
<p>How can the pres... | g13531 | [
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<p>I am trying to understand how a real world beam of laser actually reflects the physics description of oscillating electromagnetic waves.</p>
<p>So say we are looking side on at a vertically polarized laser beam, and this is section of it propagating through free space:</p>
<p><img src="http://i.stack.imgur.com/9qq... | g13532 | [
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<h2>Does this integral converge?</h2>
<p>My question is related to this one:
<a href="http://physics.stackexchange.com/questions/23682/free-particle-propagation-amplitude-calculation">Free particle propagation amplitude calculation</a></p>
<p>I am reading the book of Peskin and Schroesder. In the second page of thei... | g13533 | [
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0.03839... |
<p>The question:</p>
<p>How would you make a semi transparent mirror (50% reflection, 50% transmission) with glass with a layer of copper. For light $\lambda$ = 500nm Try to be as realistic as possible</p>
<p>What I've done so far. </p>
<p>The reflection coefficient of copper for 500nm light is 50%. So that's great.... | g13534 | [
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<p>I was reading the article <em><a href="http://cdn.makezine.com/make/24/Make24_weatherballoon_11x17.pdf" rel="nofollow">Weather Balloon Space Probes</a></em> that says you can put your own balloon probe at 65,000 ft temporarily. </p>
<p>Is it even remotely possible to raise the probe high enough using <a href="... | g13535 | [
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<p>In 1+1 dim bosonization, one introduce the Klein factors, which are Hermitian and satisfies Clifford algebra. </p>
<p>(1) In the case of <strong>1 dim space is a 1D ring ($S^1$ circle)</strong>, then one have left-right boson field commutes
$$[\phi_L, \phi_R]=0$$
but introduces Klein factor to reproduce the fermio... | g13536 | [
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<p>Consider a system in which atoms are located in a regular lattice, each atom having a spin $1/2$ and an associated intrinsic magnetic moment $\mu_0>0$. Assume that each atom interacts only weakly with other atoms so that all the other atoms act as a heat reservior. If the system is placed in an external magnetic ... | g13537 | [
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<p>Conceptually, I understand that coaxial cables operate in a TEM mode due to the central conductor, and hence the electric field is directed radially outward from the voltage $V_0$ at the centre of the cable, to the supposedly grounded outer cable (the derivation for this involving Poisson's equation and such). Simil... | g13538 | [
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<p>I've read that electroweak symmetry breaking occurred "at a picosecond or so" after the Big Bang (in <a href="http://delphiwww.cern.ch/talks/general/Treille.tianjin2012/origin_tianjin_corr_reduced.pdf" rel="nofollow">a source I found</a>).</p>
<p>I can't help wondering why it took so long to get started. For insta... | g13539 | [
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<p>The problem in Sredniki's textbook 10.5 :</p>
<p>For a free scalar field $\psi$, the Lagrangian is
$$\cal{L}= -\frac{1}{2}\partial^\mu\psi\partial_\mu\psi-\frac{1}{2}m^2\psi^2$$
Here we use the metric $\operatorname{diag}(- + + +)$</p>
<p>If I make $\psi=\phi+\lambda \phi^2$, then the Lagrangian is
$$\cal{L}= -\f... | g13540 | [
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<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://physics.stackexchange.com/questions/843/maxwells-demon-constant-information-energy-equivalence">Maxwell's Demon Constant (information-energy equivalence)</a> </p>
</blockquote>
<p>I was reading:</p>
<p><a href="http://www.scientificam... | g422 | [
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<p>What do you guys think of <a href="http://www.dilbert.com/blog/entry/what_is_the_universe_made_of/" rel="nofollow">Scott Adams' theory</a> that the Universe might be made of recursions, created by observation?</p>
<p>I find it fascinating but have no strong opinion yet if it makes sense.</p> | g13541 | [
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<p>The mistery of the mass of the top being in the electroweak scale can be justified by the Higgs mechanism itself; in some sense the top mass is the only "natural" mass, the other masses of fermions being protected by some unknown mechanism so that they are "zero" relative to the electroweak: the typical values of th... | g13542 | [
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<p><sup>[Remark: I admit that my first attempt on <a href="http://physics.stackexchange.com/questions/994/what-makes-a-space-a-real-space">What makes a space a real space?</a> was rather ill-posed and led to some confusion. Sorry for that, but please give me a second try. Part of the confusion arose from the ununsual t... | g13543 | [
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<p>In my physics class, we did an experiment in which we supported Ohm's law. We used a simple circuit that includes one resistor. The relationship of I = VR, and variants thereof, became apparent. We mainly looked at the relationship between potential difference and the current in series.</p>
<p>What we have not done... | g13544 | [
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<p>Because of the image forced barrier lowering the barrier potential reduces in reverse bias . What happens to barrier height (potential) in forward bias??</p> | g13545 | [
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<p>I have been taught in school that atoms cannot have more than 8 electrons in the outer shell. <a href="http://en.wikipedia.org/wiki/Palladium" rel="nofollow">Palladium</a> atom's electron configuration is 2,8,18,18. Why isn't it 2,8,18,17,1 like the case of Platinum 2,8,18,32,17,1 or Nickel 2,8,17,1 and they are all... | g13546 | [
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<p>This is more of a theoretical thought-experiment question.</p>
<p>Basically, how much geothermal energy can we extract before the loss of the magnetic field makes it a terribly bad idea?</p>
<p>Will the geothermal energy inside the earth now, which is lost through "natural processes", last until the end of the Sun... | g13547 | [
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<p>Gell-Mann and Hartle came up with the <a href="http://arxiv.org/abs/1106.0767" rel="nofollow">extended probability ensemble interpretation</a> over <a href="http://arxiv.org/abs/0801.0688" rel="nofollow">here</a>.</p>
<p>Basically, they extended probability theory to include real numbers which may be negative or gr... | g13548 | [
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<p>Today, I tried creating a very basic Faraday cage by surrounding a radio with two baking trays made out of iron. It didn't seem to affect the radio's signal (AM was being used, not FM).</p>
<p>In theory, should what I used block the radio's signal?</p>
<p>I can't remember how thick the baking trays were. There was... | g13549 | [
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<p>As given on this <a href="http://en.wikipedia.org/wiki/Supercritical_fluid" rel="nofollow">link</a>, supercritical fluids are viewed more as a continuum which has both liquid and gas properties. This continuum is obtained when a gas is brought to a pressure and a temperature higher than its critical values. The inte... | g13550 | [
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<p>With crude calculations following densities can be approximated:</p>
<p>Given that radius of proton is $1.75×10^{−15} m$ and it's mass is $1.67 × 10^{-27}kg$, this gives density of proton to be $\dfrac {1.67 × 10^{-27}kg} {\frac{4}{3}(1.75×10^{−15} m)^3}=\dfrac {3}{4} \dfrac{1.67 × 10^{-27}}{5.36×10^{−45}} \dfrac{... | g13551 | [
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<p>Using classical mechanics, the formula for gravitational attraction is </p>
<p>$$F = G\frac{m_1m_2}{r^2}.$$ </p>
<p>This formula does not work for photons, and we need to use Einstein's theory of gravity to account for that, as the photon is massless. What if, instead of using the mass of the photon, we rather use... | g13552 | [
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<p>Ammeter (A1) and voltmeter (V) in series have parallel connection to another ammeter (A2). Currents in A1 and A2 are respectively 0.2 and 1.7 amp. Voltmeter's voltage is 6 volts.</p>
<p><img src="http://i.stack.imgur.com/w9oZl.png" alt="enter image description here"></p>
<p>How should I find resistances of all ele... | g13553 | [
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<p>Could a ship equipped with Alcubierre drive theoretically escape from a black hole?</p>
<p>Also, could it reach parts of the universe that are receding faster than the speed of light from us?</p> | g13554 | [
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<p>Could the Opera result be interpreted as some kind of hint to a discrete spacetime that is only seen for high enough energy neutrinos?</p>
<p>I think I've read (some time ago) something like this in a popular article where among other things tests of quantum gravity theories, that assume a discrete spacetime, are e... | g13555 | [
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<p>Let there be given two Hamiltonians</p>
<p>$$H_1~=~ p^{2}+f(x) \qquad \mathrm{and} \qquad H_2~=~ p^{2}+g(x). $$</p>
<p>Let's suppose that for big big $x$, the potentials are asymptotically similar in the sense that the quotient</p>
<p>$$ \frac{f(x)}{g(x)}~\to~1 \qquad \mathrm{for}\qquad x \to \infty.$$</p>
<... | g13556 | [
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<p>Nuclearity is a postulate in algebraic quantum field theory (AQFT). Basically, it says thermal states at any temperature always have a thermodynamic limit with extensive quantities. This is violated by string theory at the Hagedorn temperature. Does this mean anything?</p> | g13557 | [
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<p>I am not a physiologist, but whatever little I know about human eyes always makes me wonder by its details of optical subtleties. A question always comes to mind. Are human eyes the best possible optical instrument evolved by natural selection? Is there any possible room for further major improvement as per the laws... | g13558 | [
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<p>UFOs as shown in movies are shown as disk like objects with raised centers that emit some sort of light from bottom. Can such a thing fly?</p>
<p>My very limited knowledge in physics tell me that a disk like object may not be able to maneuver unless it has thrusters on sides and simple light can not be enough to ma... | g13559 | [
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<p>Magnetic field lines depict the strength of the magnetic field, dense lines in a region imply a strong field. </p>
<p>Lines are drawn as per our convenience. We needn't draw infinite lines but just relative amounts: where the field is stronger, more lines; where it isn't, less lines. </p>
<p>What I wanted to ... | g423 | [
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<p>I have read the explanation for this in several textbooks, but I am struggling to understand it via Archimedes' principle. If someone can clarify with a diagram or something so I can understand or a clear equation explanation that would be great. </p> | g13560 | [
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<p>If an object is dropped from a roof with no initial velocity and wind is blowing along the side of the building exerting a constant force on the object, then its trajectory will be a straight line. But if the object has an initial velocity downwards, then its trajectory will be a parabola instead (according to my bo... | g13561 | [
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0.0273577... |
<p>I read <a href="http://en.wikipedia.org/wiki/Magnetic_dipole" rel="nofollow">Magnetic Dipole</a> point source in computational electro-magnetic literatures where it is used as exciting source. But I do not know how to plug this source into <a href="http://www.spec2000.net/06-electromag.htm" rel="nofollow">Maxwell's ... | g13562 | [
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<p>I've been studying Fluid Mechanics recently and on the book <em>Fundamentals of Fluid Mechanics 7e, Munson et al.</em> on page 456, the book states</p>
<blockquote>
<p>Another common multiple pipe system contains pipes in parallel ... However, by writing the energy equation between points A and B it is found that... | g13563 | [
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<p>Suppose we have some inclined plane, and there is some chain of balls of length $l$ and mass $m$ lying on it. No friction at all in the system.</p>
<p>1) What is $x_0$ (the vertical hanging part of the chain) needed for the chain to be in equilibrium? </p>
<p><em>Answer</em>: $l/3$</p>
<p>2) If we push the chain ... | g13564 | [
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<p>This has been <a href="http://physics.stackexchange.com/questions/57481/the-bizarre-behaviour-of-superfluids-climbing-up-walls-and-geting-out-of-glass">asked </a> but I couldn't find a good answer why does super-fluid climb up the walls of container? What if the walls were too high? What forces are involved?</p>
<p... | g13565 | [
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<p>This question is the continuation of <a href="http://physics.stackexchange.com/questions/89367/how-to-find-proper-speed-relate-to-homogeneous-cosmic-background-of-the-galaxy">this one</a>. I came up with solution, but I'm not sure that it is correct. Can someone check it?</p>
<p>Let's introduce transverse (to the o... | g13566 | [
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<p>I have an object I can rotate with a given torque. I would like to stop applying torque once I've reached a defined maximum rotational speed. The maximum rotational speed should be defined so that applying maximum torque will stop the rotation of the object within one rotation. If I know my torque and moment of iner... | g13567 | [
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<p>While studying Srednicki's book on quantum field theory, I encountered a particular identity that is of interest to me (equation 36.40):
$$\mathcal{C}^{-1}\gamma^\mu\mathcal{C}=-(\gamma^\mu)^T$$
where $\mathcal{C}$ is the charge conjugation operator, and $\gamma^\mu$ the well-known gamma matrices. This identity is s... | g13568 | [
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<p>I've been trying to wrap my mind around the concept of <a href="http://www.google.com/search?q=anti-time" rel="nofollow">anti-time</a> and wondered what it is. If there is anti-matter and anti-gravity, does time have its negative? Your help is appreciated.</p> | g13569 | [
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<p>In thermodynamics the total energy of a system consists of kinetic energy of motion of the system as a whole, potential energy of the system as a whole due to <em>external</em> force fields, and energy contained within the system known as internal energy,
$$
E = E_{\mathrm{k}} + E_{\mathrm{p}} + U \, . \tag{1}
$... | g13570 | [
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<p>From the maths governing an LC circuit (eg. $E_B=\frac{LI^2}{2}$) we can deduce, that the current through the inductor will have a maximum value, when there's no energy stored in the capacitor, or else $E_B = max \iff I=max$. But how to explain it intuitively?
Suppose we have a fully charged capacitor and we connect... | g13571 | [
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<p>In <a href="http://arxiv.org/abs/1308.4055" rel="nofollow"><em>Why decoherence solves the measurement problem</em></a> by Art Hobson:</p>
<p>$|\psi \rangle _{SA} = c_1|s_1 \rangle |a_1 \rangle + c_2 |s_2\rangle |a_2 \rangle$
which is a wavefunction that describes non-local entangled state of system $S$ with measuri... | g13572 | [
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<p>Firstly, I understand and apologize that this is more of a physics question than a math question.</p>
<p>I noticed that when I pulled a book out from under a pack of gum, the gum stayed largely in place (it did not move with the book). This confused me, so I decided to draw a diagram of the situation, assuming that... | g13573 | [
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<p><a href="http://www.cheniere.org/books/aids/ch4.htm" rel="nofollow">This page</a> claims that original Maxwell's equations, when formulated by Maxwell himself in quaternion form, had some special scalar part of electromagnetic field, which somehow appeared to describe gravitation. The author says that further develo... | g13574 | [
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<p>Certain "whitening" toothbrushes are sold and I was wondering about the mechanisms behind the tooth whitening process. I suspect this is related to the shape and arrangement of the fibres, probably somewhat similar to how a microfiber cleaning cloth works, but couldn't find any authoritative confirmation.</p>
<p>S... | g13575 | [
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<p>I understand that playing a square wave from speakers cannot produce a PERFECTLY sharp division between compression and rarefaction. But it's sharp enough to sound distinctly different from a sine wave. As it travels, does the wave "smoosh out" even further as it travels, changing from a square wave into something... | g13576 | [
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<p>Internet providers try to sell us the more and faster "fast internet" - 15Mb, 40Mb, 100Mb, and so on. But it's well known that the bandwidth the channel (in the most cases it's the telephone wire) restricted by the nature law. And this law is so fundamental as the light speed. (see, e.g., V.A.Kotetlnikov theorem). T... | g13577 | [
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<p>I was wondering if there exist a particle analogous to the Higgs boson that gives rise to energy, I´m sorry it´s not the big question but I feel confused about how the universe works, also I have been searching and I couldn't find anything</p> | g13578 | [
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<p>I'm a third year physics undergrad with a very cursory knowledge of quantum mechanics and the formalism involved. For instance, I understand roughly how tensors work and what it means for a tensor to be irreducible, though it would take me a lot of work to apply this knowledge to a problem/extend it past what I've a... | g13579 | [
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<p>Assume that we have a particle with weight m and initial speed v0, that follows a roller coaster path y(x).
<img src="http://i.stack.imgur.com/kyUeA.png" alt="Roller Coaster Path"></p>
<p>Assuming no energy loss to friction or air resistance, the total energy in the system is </p>
<p>$$E0 = m g y(x0) + 0.5 m vo^2$... | g13580 | [
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<p>I know that this is a homework type question and I'm not asking a particular physics question, but I'm really desperate for help.</p>
<p>Here's the question:</p>
<p><img src="http://i.stack.imgur.com/Ob5xP.png" alt="enter image description here"></p>
<p>I tried to divide the string to 2 parts with $O$ as the mid-... | g13581 | [
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<p>I'm trying to calculate Stoke's drag constant using the equation found <a href="http://en.wikipedia.org/wiki/Drag_%28physics%29#Very_low_Reynolds_numbers_.E2.80.94_Stokes.27_drag" rel="nofollow">here</a>.</p>
<p>The system I wish to calculate it for is a mass oscillating vertically on a spring through air. The temp... | g13582 | [
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<p>Calculating the transition amplitude in Euclidean spacetime is useful because from it we can extract the ground state energy and ground state wave-functions values.</p>
<p>For example, let's assume we are calculating:
$\left<x=b\left.\right|e^{-\hat{H}T}\left.\right|x=a\right>$. Assume we can calculate this q... | g13583 | [
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<p>This question may seem odd, but I can't think of anything better. So I'll go straight to the point.</p>
<p>Let's say there's a projectile in air going east, shot at a certain angle, with a certain speed. Then there's the wind blowing, for let's say 5 meters per second in the same direction as the projectile.</p>
<... | g13584 | [
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<p>Which cosmologies consistent with physics as we currently know it is consistent with Eternal Life lasting forever starting from here on Earth while preserving the memories of human life? With computers and robots colonizing the universe and growing without bound?</p>
<p>Tipler had suggested an Omega Point associate... | g13585 | [
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<p>Why zeta regularization only valid at one-loop? </p>
<p>I mean there are zeta regularizations for multiple zeta sums.
Also we could use the zeta regularization iteratively on each variable
to obtain finite corrections to multiple loop diagrams.</p> | g13586 | [
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<p>AFAIK radio waves can be influenced by magnetic fields (when not traveling through a vacuum). Electrical wires create a magnetic field perpendicular to the length of the wire, as a function of the current running through it.</p>
<p>In air, water, or other medium, would radio waves be influenced by this magnetic fie... | g13587 | [
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<p>Considering Einstein equations, suppose, for instance, that the RHS, the stress-energy tensor, is uniquely due to the electromagnetic field. Now, if we imagine a quantized version of these Einstein equations, we have a quantum field theory in $D$ dimensions (here the quantum electromagnetic field) as "source" of a "... | g13588 | [
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<p>Any <a href="http://en.wikipedia.org/wiki/Free_and_open-source_software" rel="nofollow">FLOSS</a> Monte-Carlo package for reactor physics? Are there any Free and Open Source software packages for nuclear reactor processes simulation? Maybe, something similar to <a href="http://mcnp.lanl.gov/" rel="nofollow">MCNP</a>... | g13589 | [
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<p>Are electrons of any conductor really free ? I mean are they always already moving or do they move only when electrostatic field of some sort is applied across them. I suppose if they were always moving each and every conductor must have some varying magnetic field around it at all times which though negligible mus... | g424 | [
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<p>The <em>no hair</em> theorem says that black holes rapidly converge to a state that is completely described just by their mass, spin and charge. Black hole thermodynamics says that the black hole entropy is proportional to the surface area of the event horizon. As I understand it in information theoretic terms the b... | g13590 | [
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<p>As the title asks, how do you represent an equation with four variables? Is there a practical way of representing them? (I've thought of one, but I don't think I can explain it clearly. This question has got me really curious.) Additionally, is there any practical way of solving these equations?</p> | g13591 | [
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-0.021568631753325462,
0.004391126800328493,
... |
<p>I can turn-the-crank and show that $\frac{1}{2}\otimes \frac{1}{2} = 1\oplus 0$ etc, but what would be a strategy to proving the general statement for spin representations that $j\otimes s =\bigoplus_{l=|s-j|}^{|s+j|} l$. </p> | g13592 | [
-0.04144466295838356,
0.013713778927922249,
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0... |
<p>In quantum mechanics, particles are described by wave functions, which describe probability amplitudes. In quantum field theory, particles are described by excitations of quantum fields. What is the analog of the quantum mechanical wave function? Is it a spectrum of field configurations (in analogy with QM wave func... | g13593 | [
0.02548377215862274,
0.0007605054415762424,
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0.016... |
<p>As I've said elsewhere, I've not had the opportunity to take a class in general relativity. Nonetheless, I understand that two major aspects of the standard cosmological model are the <a href="http://en.wikipedia.org/wiki/Cosmological_principle" rel="nofollow">cosmological principle</a> and the observation of a <a ... | g13594 | [
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0.018... |
<p>Few years ago I read some papers about Free Energy, written by Bruce de Palma, a physicist who is said to be the inventor of the N-Machine, which is an device that works with free energy latent in the space around us. There are several informal references to him and <a href="http://www.brucedepalma.com/" rel="nofoll... | g13595 | [
0.021567054092884064,
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0.0001... |
<p>I) I know that virtual-photons are known to be the force-carriers for the Electromagnetic force, and that they are called "virtual" because the Energy-Time-inequality version of the Heisenberg Uncertainty Principle allows for particles that are high enough energy that they are very difficult to observe (because high... | g13596 | [
-0.010443451814353466,
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0.010397326201200485,
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0.005069267470389605,
0.0114460363... |
<p>Goldstein pg 151 says "it is clear that an inversion of a right-handed system into a left-handed one cannot be accomplished by any rigid change in the coordinate axis..." I am trying to understand what he means by a rigid change... is he saying that an inversion is a discontinuous jump that is impossible for an ob... | g13597 | [
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0... |
<p>Based on my limited knowledge of nuclear physics, it seems that one day it may/will be possible to synthesize whatever elements we may need, given enough energy. Is this accurate?</p>
<p>Is there a table that lists the most efficient ways to create certain elements from more abundant ones via fusion or fission?</p>... | g13598 | [
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... |
<p>I made comparison between Doppler effect in light and sound and one interesting thing that I saw was that in the case of sound there are different formulas to find the apparent frequency in different situation (like observer moving,source moving,both moving etc) due to Doppler effect but in the case of light there i... | g13599 | [
0.04424425587058067,
0.016408177092671394,
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0.05113864690065384,
0.13... |
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