question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
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<p>I have a vacuum chamber with a pressure 10<sup>-8</sup> Torr.
Then I open an Oxygen valve with a set flow of 2 sccm from a tank with a pressure of 2 bars. The pressure in the chamber decreases to 10<sup>-2</sup> Torr. What is the partial pressure of the Oxygen in the chamber?</p>
<p>Is it 10<sup>-6</sup> Torr or 10... | g11573 | [
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<p>NASA is providing very brief updates on the <a href="http://www.nasa.gov/mission_pages/uars/index.html" rel="nofollow">reentry of the UARS satellite</a>. They also published an extensive study of the <a href="http://www.nasa.gov/pdf/585584main_UARS_Status.pdf" rel="nofollow">Re-entry and risk assessment for the NAS... | g11574 | [
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<p>I am doing photometric calibration of a telescope and am trying to work out the errors on the flux that I measure. I have attempted to work out the errors due to the process of removing bias, dark frames, etc. using Poisson statistics, but this gives a fractional error of about 0.7, which is poor. I may try this ana... | g11575 | [
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<p>Could a neutron star be a bit like our Sun or any other star?</p>
<p>Just to have a different scale: </p>
<p>A neutron star fusioning not hydrogen and other elements but neutrons and quarks in its core at a stable, constant speed, would release energy, and the neutron star would therefore be larger than just packe... | g11576 | [
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<p>I'm working on a 2d physics simulation. It's a continuous time simulation, that is, it uses swept shapes over the time-frame and geometrical/vector 'analysis' to determine most immediate time of contact. The world is then stepped forward to that point and collisions are resolved before proceeding to step the world f... | g11577 | [
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<p>If for some reason, an Astrophysics graduate decides to shift to Finance will he/she be in a better position (given his/her overspecialization) to make a transition compared to his/her counterparts who've been doing Analytical/Observational Astrophysics?</p> | g11578 | [
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<p>Are there any resources online for astronomy experiments that I can perform myself?</p>
<p>I am looking if anyone knows any measurements to take while looking for various objects during the evening particularly using a telescope/binoculars.</p>
<p>A couple of examples would be determining the orbits of the moons o... | g11579 | [
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<p>I have this question: $q_1$ is a Uniformly Charged long Wire(inf in z axis) with $\lambda$ (charge per unit length).<br>
In (0,0,0) I have A very long conducting cylinder of radius a (also inf in z axis). <strong>NOT GROUNDED!!!</strong><br>
I want to find the electric potential everywhere. Where do i start? thanks!... | g11580 | [
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<p><strong>"Masses $M_1$ and $M_2$ are connected to a system of strings and pulleys as shown. The strings are massless and inextensible, and the pulleys are massless and frictionless. Find the acceleration of M1.
(Clue if $M_2 = M_1$, A(acceleration)=g/5.)”</strong>
(The problem is from “An Introduction to Mechanics” –... | g11581 | [
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<p>I'm not sure if this is the right place to ask this question. I realise that this maybe a borderline philosophical question at this point in time, therefore feel free to close this question if you think that this is a duplicate or inappropriate for this forum. Anyway, I'm an electrical engineer and I have some basic... | g634 | [
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<p>As I understand it, the renormalization group is only a semi-group because the coarse graining part of a renormalization step consisting of </p>
<ol>
<li><p>Summing / integrating over the small scales (coarse graining)</p></li>
<li><p>Calculating the new effective Hamiltonian or Lagrangian</p></li>
<li><p>Rescaling... | g11582 | [
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<p><img src="http://i.stack.imgur.com/nKuqh.jpg" alt="enter image description here"></p>
<p>That is what my crystal structure looks like. The blue atoms sit on every lattice point (basis vector of $\{0,0\}$) and the red atoms have basis vector of $\left\{{2\over3},{1\over3}\right\}$. The lattice vectors are:</p>
<p>$... | g11583 | [
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<p>I read on the website of European Space Agency that the altitude of Galileo satellites, which is 29600 Km from the center of the Earth, is chosen to avoid gravitational resonances so that station keeping manoeuvres are not needed during the lifetime of a satellite. </p>
<p>Note: I read before that GPS satellites' m... | g11584 | [
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<p>In my book they don't really derive the equation of the magnetic field inside of a finite solenoid. They just give me equation 1 and image and the end result, equation 2.</p>
<p>$$dB=\frac{\mu_0Ndlr^2I}{2ly^3}\tag{1}$$
<strong>Equation 1: contribution of $dl$ for $dB$ in point P</strong></p>
<p><img src="http://i.... | g11585 | [
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<p>Aluminum foil is said to be <em>not</em> absorbing light at all.
It reflects light. So, does it mean that a more shiny aluminum foil will reflect more light and thus make the room more cooler as compared to less shiny foil?</p>
<p>If yes, then where does unreflected light go in case of less shiny aluminum foil?</p>... | g11586 | [
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<p>If a baryon wavefunction is $\Psi = \psi_{spatial} \psi_{colour} \psi_{flavour} \psi_{spin}$,
and we consider the ground state (L=0) only.
We know that the whole thing has to be antisymmetric under the interchange of two quarks. We know that colour is antisymmetric (always colourless) and spatial is symmetric. There... | g11587 | [
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<p>I know that there are some metals that just "like" to be on a surface, so if I make an alloy of such metal and some other metal, the first one will be on the surface after solidification of initially liquid alloy. This happens due to reduction of free surface energy, and I think that Gibbs' equation would be helpful... | g11588 | [
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<p>I am currently working my way through John S. Townsend book "A Fundamental Approach to Modern Physics" (ISBN: 978-1-891389-62-7). Exercise 3.12 (p.111) is about the 1D infinite square well. The box has the potential barriers at $x=0$ and $x=L$.
$$
V\left(x\right) = \begin{cases} \infty & x < 0 \\ 0 & 0 \l... | g11589 | [
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<p>Is more of the thermal radiation due to acceleration of electrons or acceleration of the nuclei? Do electrons and nuclei carry the same fractions of thermal energy in a hot body? </p> | g11590 | [
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<p>From <a href="http://en.wikipedia.org/wiki/Coherent_states" rel="nofollow">Wikipedia</a>:</p>
<blockquote>
<p><em>[...]Off-diagonal long-range order (ODLRO) [...] exists whenever there is a macroscopically large factored component (eigenvalue) in a reduced density matrix of any order.</em></p>
</blockquote>
<p>H... | g11591 | [
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<p>According to the kinetic molecular theory obeying Maxwell-Boltzmann distribution of speeds, the rate of effusion through a pinhole of area $A$ is<br>
$$R=\frac{PA}{\sqrt{2\pi M R T}}$$ where $M$ is the molecular weight, $R$ is the gas constant and $T$ the absolute temperature. </p>
<p>To derive this, I consider th... | g11592 | [
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<p>Suppose your have any magnetic object and no external force acts upon it, and the object comes near a metal which causes an impulse (think that will happen). However, the magnetic force is internal to the object, and momentum should be conserved, so where have I gotten it wrong?</p> | g11593 | [
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<p>What are the Physics/Astrophysics blogs you regularly read? I'm looking to beef up my RSS feeds to catch up with during my long commutes. I'd like to discover lesser-known gems (e.g. not well known blogs such as Cosmic Variance), possibly that are updated regularly and recently.</p>
<p>Since this is a list, give on... | g11594 | [
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<p>I've been reading about fusion fuels for a while now, and I understand that in Lithium-Deuterium fuel, the neutrons from the fission reaction bombard the Lithium to produce Tritium and the D-T reaction occurs and we get the energy.</p>
<p>So what about Deuterium-Deuterium fusion ? Is it possible without the presenc... | g11595 | [
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<p>I'm a big fan of the podcast Astronomy Cast and a while back I was listening to a Q&A episode they did. A listener sent in a question that I found fascinating and have been wondering about ever since. </p>
<p>From the show <a href="http://www.astronomycast.com/listeners/questions-shows/questions-show-decelerati... | g112 | [
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<p>All big rockets are burning either gas or fluid to create thrust. While this is so, I have filled up a plastic bottle with air at high pressure, and it can go long distances by blowing the pressurised air at reverse direction. If my bottle can do this without using any fire, why don't rockets just use air? How is th... | g11596 | [
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<p>Something I have read multiple times that I've never intuitively understood is that "heavier" particles are harder to detect than "lighter" ones... For example, I quote from Stephen Hawking's "The Grand Design" in relation to supersymmetry:</p>
<blockquote>
<p>But various calculations that physicists have perfo... | g11597 | [
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<p>Say you have two charged capacitors in series. Zoom in on one capacitor. For this specific capacitor, the charge on the two plates will be the same in magnitude, according to my textbook.</p>
<p>My teacher said that the charge on the two plates won't be the same if the gap between the the plates is large. In fact, ... | g11598 | [
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<p>If the earth's gravity exerts a net downward gravitational force on all air molecules, how come the molecules don't eventually lose their momentum and all settle down? How is the atmosphere is still miles thick after billions of years?</p> | g11599 | [
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<p>Suppose we have a block A and is moving on a rough horizontal surface with a velocity 60 m/s and another block B of same mass moving with velocity 5 m/s on same horizontal surface and suppose they move same distance . The block A due to friction gets more tear on its bottom surface than block B so can we conclude t... | g11600 | [
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<p>We've previously discussed why it is that spinning tops do not fall over, see: <a href="http://physics.stackexchange.com/questions/271/why-dont-spinning-tops-fall-over">Why don't spinning tops fall over?</a></p>
<p>However, as the highest rated answer notes, the angular momentum of the spinning top is "quite high".... | g11601 | [
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-0.006880371365696192,
-0.00587218813598156,
0.0037703944835811853,
0.01658938080072403,
-0.0... |
<p>As I read in <a href="http://rads.stackoverflow.com/amzn/click/0679454438" rel="nofollow">The Road to Reality</a> by <a href="http://en.wikipedia.org/wiki/Roger_Penrose" rel="nofollow">Roger Penrose</a>, the <a href="http://en.wikipedia.org/wiki/Joukowsky_transform" rel="nofollow">Joukowsky transform</a> $$w(z) = \f... | g11602 | [
-0.016228867694735527,
-0.026041343808174133,
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0.007908753119409084,
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0.... |
<p>I am aware about different interpretations of quantum mechanics out there but would mostly like to see an answer from the perspective of Copenhagen interpretation (or relative quantum mechanics if you wish).</p>
<p>Let an observer being a man with brain consisting of molecules and atoms. According the basic princip... | g11603 | [
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<p>I looked at the wikipedia entry and it doesn't give a very detailed or thorough description of the principles of operation of Barkhausen-Kurz oscillator triodes. But I do wonder if it is physically possible to design such a self-oscillating thermionic valve(DC input) that can oscillate in the audio frequency range(2... | g11604 | [
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<p>While riding a bike at a higher velocity, I go over the speed breakers (Hump)
I get jumped over the bike for a certain height. How do I calculate this height of jump with respect to the seat of the bike?</p> | g11605 | [
0.05876396223902702,
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<p>This should hopefully be a quick one.</p>
<p>Is there any difference between the <a href="http://www.google.com/search?as_q=&as_epq=big+bang" rel="nofollow">Big Bang Theory</a> and the <a href="http://www.google.com/search?as_q=&as_epq=hot+big+bang" rel="nofollow">Hot Big Bang Theory</a>?</p>
<p>Around Cam... | g11606 | [
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0.0... |
<p>For some experimental and practical reason, I have created a new coordinate system in the form</p>
<p>$$x^\prime_i=T_{ij}x_j$$</p>
<p>where $T_{ij}$ <strong>isn't</strong> a square matrix. $x_i$ is standard Cartesian coordinates, and $x^\prime_j$ is a point in the new system. I have to mention that the new system'... | g11607 | [
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0.035900890827178955,
-0.013341664336621761,... |
<p>If you take a look at <a href="http://www.youtube.com/watch?v=izy4a5erom8" rel="nofollow">this video</a> you will see what kind of a coupled pendulum I'm talking about.</p>
<p>So I made a similar one in my high school's physics lab, using light metal bobs(much lighter than the Easter eggs he's used in the video) an... | g11608 | [
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0.02... |
<p>$$
\DeclareMathOperator{\dif}{d \!}
\newcommand{\ramuno}{\mathrm{i}}
\newcommand{\exponent}{\mathrm{e}}
\newcommand{\ket}[1]{|{#1}\rangle}
\newcommand{\bra}[1]{\langle{#1}|}
\newcommand{\braket}[2]{\langle{#1}|{#2}\rangle}
\newcommand{\bracket}[3]{\langle{#1}|{#2}|{#3}\rangle}
\newcommand{\linop}[1]{\hat{#1}}
\newco... | g11609 | [
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<p>I have taken only QM I, which is the 1st half of Griffiths including the chapter on identical particles, will that be enough to understand Kittel's solid state? </p>
<p>Should one have also taken a course in statistical mechanics before studying kittel?</p>
<p>I have seen in some universities in the states that th... | g11610 | [
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<p>When a wire that has current $I$ flowing within it and its in a magnetic field, the wire experience the Lorentz force, and that force moved the wire over a certain distance $x$(no matter how small), can we state that work is done by the Lorentz force on the wire? </p>
<p>If so...</p>
<p>What kind of energy is tra... | g11611 | [
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<p>$\alpha_L = \frac{1}{a}\frac{da}{dT}$</p>
<p>I know error in $a$, i.e., $da$</p>
<p>I need to find out $d\alpha$ from data of $da$.</p>
<p>$d\alpha_L = -\frac{1}{a^2}\frac{da}{dT}da$</p>
<p>Is this correct?</p>
<p>Note: </p>
<p>$\alpha_L$ = Linear thermal expansivity</p>
<p>$a$ = Lattice constant</p> | g11612 | [
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0.0... |
<p>In many theoretical setups it is implicitly assumed that the underlying manifold (i.e. spacetime) is orientable. Then our analysis depends on this implicit assumption. For example, Stokes' theorem assumes orientability of the chain on which we integrate. However, we accept that time "always" points forwardly.</p>
<... | g11613 | [
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<blockquote>
<p>A wind-powered generator converts wind energy into electrical energy.
Assume that the generator converts a fixed fraction of the wind energy
intercepted by its blades into electrical energy. For wind speed $v$,
show that the electrical power output will be proportional to $v^3$.</p>
</blockquote... | g11614 | [
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<p>Is it possible to make a metallic object move in a circular contained tube around and around in which a magnetic field is setup to cause the metallic object to move through the electric field within the tube through magnetic forces alone? If not, what other forces must be present to make the object move around and ... | g11615 | [
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<p><a href="http://uqu.edu.sa/files2/tiny_mce/plugins/filemanager/files/4190016/Quantum_Mechanics_1/ch4-virtual-book.pdf" rel="nofollow">http://uqu.edu.sa/files2/tiny_mce/plugins/filemanager/files/4190016/Quantum_Mechanics_1/ch4-virtual-book.pdf</a></p>
<p>On page 2 of the above pdf they describe how they select their... | g11616 | [
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0.00016953196609392762,... |
<p>My professor told me recently that Area is a vector. A <a href="http://www.google.co.in/#sclient=psy&hl=en&source=hp&q=what%20is%20a%20vector&pbx=1&oq=what%20is%20a%20ve&aq=1&aqi=g5&aql=&gs_sm=sc&gs_upl=1666l6221l0l7939l12l9l0l2l2l0l541l3051l2-3.1.2.2l8l0&bav=on.2,or.r_gc.... | g11617 | [
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0.02... |
<p>Equation 1.2 of <a href="http://www.staff.science.uu.nl/~hooft101/lectures/genrel_2010.pdf" rel="nofollow">'t Hooft's Introduction to General Relativity</a> gives the <em>Lorentz transformations</em>:</p>
<p>$$
(x^\mu)' = \sum\limits_{\nu = 1}^4 {L^\mu}_\nu x^\nu
$$</p>
<p>Is this the sum of four square matrices e... | g11618 | [
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0.00025505057419650257,
... |
<p>I've read that the angle for viewing a Primary Rainbow is between 40-42 degrees. How would I go about showing this? How would I calculate that angle from scratch? I figured that Snell's Law and the Law of Reflection would be used for light bouncing off and through a (spherical) water droplet. But I only have a vague... | g11619 | [
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<p>The internal potential energy of an $N$ particle system is a general function of the coordinates of the particles: $U(r_1,...,r_N)$. In some approximations and expansions - e.g. <a href="http://www.soft-matter.uni-tuebingen.de/teaching/Tutorial_Virial_Expansion.pdf">virial expansion</a> - it is assumed that the pote... | g11620 | [
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<p>I am interested in Quantum Information and Cryptography in particular. I have gone through Neilson's text and Preskill's notes . Can someone suggest me some good text for Quantum Cryptography ? I thank you for your time.</p> | g11621 | [
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<p>When sliding a magnet over a ferromagnetic surface there is no magnetic force at all, however,there is a magnetic force only at the edge, when the magnet is being pulled of I assume the magnetic field is trying to resist.
However, a fact it noticeable, the sliding/lateral magnetic force at the edge is a lot less, by... | g11622 | [
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<p>This answer gives a great explanation of why the field inside a wire connected to a battery must be equal at all points: <a href="http://physics.stackexchange.com/questions/102930/why-doesnt-the-electric-field-inside-a-wire-in-a-circuit-fall-off-with-distance/102936#102936">Why doesn't the electric field inside ... | g11623 | [
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<p>The Hadamard Operator on one qubit is:</p>
<p>\begin{align*}
H = \tfrac{1}{\sqrt{2}}\left[\,\left(\color{darkgreen}{|0\rangle + |1\rangle}\right)\color{darkblue}{\langle 0|}+\left(\color{darkgreen}{|0\rangle - |1\rangle}\right)\color{darkblue}{\langle 1|}\,\right]
\end{align*}</p>
<p>Show that:
\begin{align*}
H^{\... | g11624 | [
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0.05686162784695625,
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0.06177197024226189,
-0.023727871477603912,
0.0725... |
<p>I read the section <em>closed forms and cycles</em> in Arnold's <em>Mathematical Methods of Classical Mechanics</em> (page 196-200), but the problems in this section is too difficult to solve in the way following the hints. What's more, There seems no other materials teach closed forms and cycles in the same way as ... | g11625 | [
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... |
<p>There is a <a href="https://www.youtube.com/watch?v=7ne0GArfeMs" rel="nofollow">lecture</a> on how facts about the cosmos can be derived form rather simple observation. Is there an analogy for the small scale? Is there a technically simple observation that would imply, say, atoms? Anything smaller?</p> | g11626 | [
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<p>As far as I know a collisions of matter and antimatter leads to the complete annihilation of both, whereby 100% of the rest mass of the particles is converted into gamma rays. Could this mechanism be responsible for the Gamma Ray bursts seen by satellites? Could therefore Gamma Ray Bursts tell us something about wh... | g11627 | [
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-0.002352... |
<p>We all know that in <a href="http://en.wikipedia.org/wiki/Rayleigh%E2%80%93Jeans_law" rel="nofollow">Rayleigh-Jeans law</a>, </p>
<p>$$N(f)df ~=~ 8\pi f^2 df/c^3.$$ </p>
<p>How do you derive $N(\lambda)d\lambda$?</p>
<p>I am sort of confused...</p> | g11628 | [
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0.0... |
<p>Given current accuracy of the techniques, is it possible to identify a real, existing tunnel (stright I think) to make the direct comparison of the speed of light and of neutrinos?
The hypotetical tunnel from CERN to OPERA would-be too long. If we were able to increase accuracies by two decades, then would a 7.3 Km ... | g11629 | [
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<p>It has been claimed by some people that Schrödinger's picture is more misleading compared to the Heisenberg principle or path integrals, and that we would be better off abandoning the Schrödinger picture in favor of either the Heisenberg picture or path integrals. However, when it comes to open quantum sys... | g11630 | [
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<p>In sports it is commonplace to distinguish</p>
<ul>
<li><p>a "<i>team</i>" (as characterized by the players who took part in a match, playing together against another team), from </p></li>
<li><p>the "<i>score</i>" (such as the final score of two teams having played a match against each other), and from </p></li>
<... | g11631 | [
0.032445214688777924,
0.05339723825454712,
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0.06674481928348541,
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0.029127592220902443,
0.01... |
<p>My physics textbook says that friction mainly arises due to intermolecular attraction between atoms of the objects in contact and clashes between peaks are only significant for rough surfaces. I was wondering, if friction arises due to intermolecular attraction, why doesn't it oppose lifting a body as well(consideri... | g11632 | [
0.05091657117009163,
0.04665118828415871,
0.006508802063763142,
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-0.03570827469229698,
0.0264128390699625,
-0.018353374674916267,
-0.04161220043897629,
-0.007... |
<p>When differential equation like Schrodinger is separable in some coordinate system? What needs to satisfy the potential ?</p> | g11633 | [
0.0006633958546444774,
0.05544460564851761,
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0.016488077118992805,
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0.0034544963855296373,
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0.006133404094725847,
-... |
<p>Are there some toy model QFTs where the <a href="http://en.wikipedia.org/wiki/Asymptotic_safety" rel="nofollow">asymptotic safety</a> scenario is realized? </p> | g11634 | [
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<ol>
<li><p>Since the concept of the singularity in a <a href="http://en.wikipedia.org/wiki/Black_hole">black hole</a> leads to infinite densities, I wonder if it is really certain that black holes exist? </p></li>
<li><p>Is there a possibility that massive objects (which are believed to be black holes) are in reality ... | g11635 | [
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0.011953100562095642,
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<p>I am trying to determine why electric field may be confined to a certain region if there is a large difference in the permitivity for example if electric field flows through water and then reaches a water air boundary. </p>
<p>I have also been reading about EM waves, is it possible to model electric field as a wave... | g11636 | [
0.005323977209627628,
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0.0317... |
<p>If we take a hydrogen atom as qubit, let</p>
<p>$\lvert0\rangle$ = unexcited state<br>
$\lvert1\rangle$ = excited state</p>
<p>then what is the meaning of measuring the qubit value in the sign basis? If the atom may only be in excited or unexcited state, but $\lvert+\rangle$ and $\lvert-\rangle$ are superpositions... | g11637 | [
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<p>I am building a 3d model of the solar system and need to figure out the position of the pole stars of each planet in order to tilt the planets in the correct direction the correct amount. I've already found the information of the pole star locations, the problem is that these are in earth relative coordinates. For i... | g11638 | [
-0.006637373939156532,
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0.08748596161603928,
... |
<p>Has quantum mechanics been studied on highly singular and/or discrete spaces? The particular space that I have in mind is (usual) <a href="http://en.wikipedia.org/wiki/Cantor_set">Cantor set</a>. What is the right way to formulate QM of a particle on a Cantor set? </p>
<p>I can only guess that:</p>
<p>i) There wil... | g11639 | [
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0.030650554224848747,
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... |
<p>In solid state physics emergent particles are very common. </p>
<ol>
<li><p>How one determines if they are gap-less excitations? </p></li>
<li><p>Do the defects in spin ice called magnetic monopoles have mass? </p></li>
<li><p>What is the mass of emergent particles in the fractional quantum hall effect (FQHE)? </p>... | g11640 | [
0.025785675272345543,
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0.0013756578555330634,
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0.017304... |
<p>Given two environments that are identical, except for air density (e.g. Cape Canaveral, but at Mount Everest's height), would launching a rocket require more or less fuel at the lower air density?</p> | g11641 | [
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<p>We restrict ourselves to ground states of translationally invariant 1d quantum systems.</p>
<p>I understand that there is the scale invariant MERA(multiscale entanglement renormalization ansatz) which describes quantum critical points in which the tensors ("isometries" and "disentaglers") are the same across differ... | g11642 | [
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<p>When a magnetic north(N) pole is placed close to an coil with out energy source, the coil behaves like an magnet and we find a North pole which opposes the magnet bar which was approximating onto the coil.</p>
<blockquote>
<p>My question is, what conditions and mathematcal treatment assure us
about the creatio... | g11643 | [
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<p>On page 24 of these lecture notes <a href="http://arxiv.org/abs/hep-th/0309149" rel="nofollow">http://arxiv.org/abs/hep-th/0309149</a> it is stated that products of chiral superfields do not suffer from short distance singularities. In other words, if I want to calculate the dimension of a composite operator built ... | g11644 | [
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<p>A friend offered me a brain teaser to which the solution involves a $195$ pound man juggling two $3$-pound balls to traverse a bridge having a maximum capacity of only $200$ pounds. He explained that since the man only ever holds one $3$-pound object at a time, the maximum combined weight at any given moment is only... | g957 | [
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<p>According to the Wikipedia article on <a href="https://en.wikipedia.org/wiki/GNSS_positioning_calculation" rel="nofollow">GNSS positioning calculation</a>, GNSS-based positioning needs $t_\text{satellite}−t_\text{receiver}$ for a series of satellites, along with the satellite positions. This is an element of <a hre... | g11645 | [
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<p>Given that the plane $y=0$ separates the vacuum ($y>0$) from the optical medium ($y<0$), I would like to calculate the trajectory of a light ray starting at the point $(x_1,y_1)$ and ending in $(x_2,y_2)$ where $x_2>x_1$ and $y_1>0>y_2$. Specifically, I would like to find the point $(x,0)$ at which th... | g11646 | [
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... |
<p>I have a telescope with focal length 1200mm. My camera has 5184x3456 pixels with size 4.3um. This combination should give me a resolution of 0.74"/pixel and thus a field of view of 1.06° x 0.71°.</p>
<p>Given this FOV and some specified center coordinates for RA and DEC, what equations will give me the max/min righ... | g11647 | [
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<p>My professor told us that the fringes formed by interference will always be countable or finite. But I am just wondering, if, it is possible to have infinite fringes? Is there such a case? I am thinking that if the slit is placed too far from the screen, an infinite number of bright fringes will form. Or, in two-sli... | g11648 | [
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0.00... |
<p><img src="http://i.stack.imgur.com/8dRQE.png" alt="enter image description here"></p>
<p>Now normally (if it was a block not rotating) all you would have to do is use $w^2 = k/m$ and $E= \frac12k(A\cos(2wt+\theta))^2 + \frac12m(Aw\sin(wt+\theta))^2$ or in other words the translational kinetic and spring potential. ... | g11649 | [
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0.001... |
<p>I have found a document refering to the following two equations </p>
<p>\begin{align*}
&\frac{\partial^2 a\left(x,t\right)}{\partial t^2}+2u\left(x,t\right)\frac{\partial^2 a\left(x,t\right)}{\partial x \partial t}+\left[u^2\left(x,t\right)-a^2\left(x,t\right)\right]\frac{\partial^2 a\left(x,t\right)}{\partial ... | g11650 | [
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0.00923... |
<p>I wonder how to determine the directions, in which the collision debris is launched when 2 asteroids collide.
I am aware of: m1*v1 + m2*v2 = m*v = m3*v3 + m4*v4 + m5*v5 + ...
and this works just fine for the masses and valocity, however I find it difficult to determine the boundaries of the directions and under what... | g11651 | [
0.0201338529586792,
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0.12798061966896057,
-0.059... |
<p>If we take the double slit experiment as a way of demonstrating the wave-particle duality, which types of particles would show an interference pattern?</p>
<p>For example, I know that electrons show such a pattern. But do protons, too? What about atoms? Where is the boundary between "wavey particles" and "classical... | g11652 | [
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0.008681... |
<p>I'm trying to write down the equations of motion for a <a href="http://en.wikipedia.org/wiki/Tetherball" rel="nofollow">tetherball</a> moving around a pole while the string is getting shorter. </p>
<p><strong>--- MAJOR EDIT ---</strong></p>
<p>I started with Lagrange:</p>
<p>$$
x(t)=l(t) \sin (\theta) \cos (\phi)... | g11653 | [
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0... |
<p>I have a question about Landau's theory of quantum phase transition. In his model, the free energy is assumed to be </p>
<p>\begin{equation}
F = f_0 + \alpha (T-T_c) \Delta^2 + \beta \Delta^4
\end{equation}</p>
<p>The ground state of the system depends strongly on the sign of $T-T_c$. In this way, we find that th... | g11654 | [
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<p>Is there an accepted analogy / conceptual aid for the Higgs field?</p>
<p>In Physics there are many accepted conceptual aids such as<br>
* Schrödinger's cat<br>
* Maxwell's Demon<br>
* I'm sure I'm missing many, but you get the idea </p>
<p>Is there an accepted/standard aid for the Higgs?<br>
I saw a ... | g183 | [
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<p>With present day materials and technology what is the physical size of a one milli Tesla magnet? How much "power" it has to attract pieces of iron? Please compare it with the objects we have around. What difference in size and "power" it gets each order of magnitude that I go up? What is a weak magnet what is a powe... | g11655 | [
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<p>I am stuck with understanding the following construction. I am breaking it up into segments which I think can be separately answered. </p>
<p>This is related to an <a href="http://physics.stackexchange.com/questions/6084/dimensional-reduction-from-31-to-21-for-caln-2-vector-superfield">earlier question of mine</a>.... | g11656 | [
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<p>Consider a rectangular slab of permanently magnetized material. The slab's dimensions are $L_x$, $L_y$, and $L_z$, and the slab is uniformly magnetized in the $\hat{x}$-direction. The slab is not accelerating or spinning. Does the slab generate an electric field?</p>
<p>In a frame where the magnet is stationary, we... | g11657 | [
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-0.02753... |
<p>I am a bio-chemist by profession and recently written an essay for a book which is related to the subject of cosmology. This is not my area of expertise. Is there a cosmologist out there who will be kind enough to review this 8 page essay for me to check it for accuracy, or perhaps give me criticism or even suggesti... | g11658 | [
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<p>Needles to say I am a visitor here. I do not belong to the science world;)</p>
<p>But I have read both of these things before:</p>
<ol>
<li>Apple falls to the ground because curved spacetime pushes it there (same force as keeps moon in orbit)</li>
<li>Apple 'falls' to ground because the ground is rushing up to mee... | g11659 | [
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-0.033248595893383026,
0.04100361466407776,
0.... |
<p>Most of us have seen microwave ovens with metal racks or shelves, which challenges the common notion that you can't (safely) put metal in a microwave oven. What's going on here? Is it a matter of these shelves being made of a specific metal (if so what are the properties that allow it to be used in a microwave ove... | g369 | [
0.029605692252516747,
0.058322738856077194,
0.017255498096346855,
0.00600854167714715,
0.049507495015859604,
0.03418521210551262,
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0.02773910015821457,
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0.011081875301897526,
0.02834673970937729,
0.07781665027141571,
-0.04460183531045914,
0.0248819... |
<p>I've been trying to compute the moment of inertia of a uniform hollow sphere (thin walled) wrt the centre, but I'm not quite sure what was wrong with my initial attempt (I've come to the correct answer now with a different method). Ok, here was my first method:</p>
<p>Consider a uniform hollow sphere of radius $R$ ... | g11660 | [
0.055204663425683975,
-0.05146295577287674,
0.0016136151971295476,
-0.04299505054950714,
0.029363209381699562,
0.006545370910316706,
0.07211058586835861,
0.0038643754087388515,
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0.044124361127614975,
-0.052699025720357895,
0.030952516943216324,
-0.010813805274665356,
... |
<p>How did Fresnel explained the phenomenon of rectilinear propagation of light using concept of half period zones?</p> | g11661 | [
0.05022343248128891,
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-0.0021034858655184507,
0.00551873492076993,
0.018772924318909645,
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0.06943878531455994,
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0.022582370787858963,
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0.030590420588850975,
0.06074235960841179,
0.082... |
<blockquote>
<p>Consider an unormalized wavefunction of a rotor at $t = 0$, a combination of $n=0$ and $n=2$ states:</p>
<p>$$\psi(\phi) = 3 - 2 \cos (2\phi).$$</p>
<p>Find the probability distribution in angle.</p>
</blockquote>
<p>The book simply takes probability as</p>
<p>$$\lvert\psi(\phi)\rvert^2 = ... | g11662 | [
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0.0033390293829143047,
0.0414670892059803,
0.053593337535858154,
0.05725563317537308,
0.044338658452034,
0.007585975807160139,
0.0466148778796196,
0.006105563137680292,
0.004910201765596867,
-0.0158913005143404,
-0.014800... |
<p>Let foo be some unit of distance and bar be some unit of time which have been chosen so that the speed of light c = 1 foo/bar. Position several observers along a line each separated by one foo, and place light sources some distance apart amongst the observers, initially off. All observers and light sources are sta... | g11663 | [
0.017351960763335228,
0.014079277403652668,
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0.052877333015203476,
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-0.02125776745378971,
0.024903500452637672,
-0.016218068078160286,
0.03300357982516289,
0.00... |
<p>Are there any quantum properties that would enable isotope fractionation?</p>
<p>For example, atoms with odd versus even numbers of neutrons are fermions and bosons, respectively. Has any work been done using the distinct properties of fermions and bosons to isolate isotopes?</p> | g11664 | [
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0.023462556302547455,
0.030407177284359932,
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0.03584064543247223,
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0.05016282945871353,
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<p>As I understand it, the value of a 4-vector $x$ in another reference frame ($x'$) with the same orientation can be derived using the Lorentz boost matrix $\bf{\lambda}$ by $x'=\lambda x$. More explicitly,
$$\begin{bmatrix}
x'_0\\
x'_1\\
x'_2\\
x'_3\\
\end{bmatrix}
=
\begin{bmatrix}
\lambda_{00}&\lambda_{01}&... | g11665 | [
0.001179036102257669,
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0.0867454931139946,
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0.012166659347712994,
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0.07221029698848724,
0.019735019654035568,
0.0086... |
<p>I want to move to Sprite Kit framework offered by apple which has physics integrated right into it. The back bone of the physics engine is famous Box2D. Sprite Kit has made it pretty easy by wrapping C++ inside Objective-C but unfortunately some features lack in Sprite Kit. One them is GetReactionForce function, th... | g11666 | [
0.007385691627860069,
0.016603387892246246,
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0.015427703969180584,
0.011749944649636745,
0.051796168088912964,
-0... |
<p>Suppose we built a enormous torus shaped space station that encompasses and leaves about 330 kilometers between it and the earth. So it's radius is about 6,371 kilometers . Obviously, this structure will have to spin very quickly to not collapse. So let's say it's going 28,000 kilometers per hour so people in the sp... | g11667 | [
0.04748496040701866,
0.01200565043836832,
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0.060512855648994446,
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0.059821225702762604,
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0.031059816479682922,
-0.031242458149790764,
0.07257618010044098,
-0.011... |
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