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| bio | website | |
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| location | ||
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| visits | member for | 9 months |
| seen | 8 hours ago | |
| stats | profile views | 64 |
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Mar 12 |
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How is Gauss' Law (integral form) arrived at from Coulomb's Law, and how is the differential form arrived at from that? Thank you, Qmechanic. |
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Mar 12 |
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How is Gauss' Law (integral form) arrived at from Coulomb's Law, and how is the differential form arrived at from that? I intuit equation (2), but why cube $\delta(\mathbf{r}-\mathbf{r_i})$? |
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Mar 12 |
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Proof that flux through a surface is independent of the inner objects' arrangement @joshphysics Thank you; yes I do. It's finally clicked where that derivation fits in to the derivation of Gauss' Law. Thank you all for the patience! |
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Mar 11 |
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Proof that flux through a surface is independent of the inner objects' arrangement I'm happy that the divergence theorem holds for general surfaces, but not $\nabla \cdot \mathbf{g}= - \rho G 4 \pi$ that needs to be put into the divergence theorem to get Gauss' Law. |
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Mar 11 |
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Proof that flux through a surface is independent of the inner objects' arrangement @joshphysics I hope it's clearer now, and yes, that was what I was looking for. |
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Mar 11 |
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Proof that flux through a surface is independent of the inner objects' arrangement Sorry about that, Poisson's equation was more of a sidenote rather than the main part of the question: I was referring to its use in the proof of Gauss' law. |
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Mar 10 |
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Can an orbit be calculated using two points and transit time? Counterexample: you can come up with an ellipse or a parabola that passes through two points in the same times. |
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Mar 9 |
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Relation between satellites' potential energy and quantum mechanical confinement energy? I got the equation from Cheng and Warner's (excellent but) fairly non-rigorous introduction to QM, so your answer's much appreciated. Thank you! |
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Mar 9 |
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Relation between satellites' potential energy and quantum mechanical confinement energy? I did guess that it was probably integer multiples of $\hbar$ (although, yes, it's not true unless $l^2+l$ is a perfect square). |
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Mar 4 |
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Does a ball thrown in the air really stop at its apex, and if it does, wouldn't that violate the uncertainty principle? Experts only ever state this as an approximation. |
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Feb 2 |
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Why does 'proper length' exist as a notion? Thanks for the edit. It reminded me that there's no smooth transition between proper length and time. The discontinuity itself is enough to abandon dreams of unification. |
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Jan 22 |
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Shape of a string/chain/cable/rope? I think I understand now- I made a mistake having the integral within the integral. |
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Jan 22 |
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Shape of a string/chain/cable/rope? And also I'm getting stuck on differentiating $\int_0^l ds$ with respect to $\dot{h}$. |
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Jan 22 |
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Shape of a string/chain/cable/rope? @nervxxx, as a sanity check, is $\lambda= \frac{g \rho}{l}$ correct? |
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Jan 19 |
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How much effect does the Bernoulli effect have on lift? Thank you! Maybe include that in the answer? |
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Jan 18 |
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How much effect does the Bernoulli effect have on lift? @MikeDunlavey: I think I didn't say it correctly or coherently there, but is it possible to compare the magnitudes of the lift produced due to the difference in pressure, meaning the force on the underside to be > the force on the top (Bernoulli), and the lift produced by the angle of attack causing the downward motion of the outgoing air, thus lifting the plane? I'd have thought that it is, as are separate phenomena (as there is no 'larger thing'), even if fundamentally caused by the same thing. |
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Jan 18 |
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How much effect does the Bernoulli effect have on lift? The second link seems to imply that conservation of momentum and Bernoulli are a facet of (or different ways of looking at) a larger thing (that thing is not the sum of them, as I understand, as they aren't cumulative). What is this larger thing? |
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Jan 17 |
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Shape of a string/chain/cable/rope? @nervxxx, I was thinking of a bog-standard piece of string, so it's not large enough to experience the effects of a varying gravitational field. I wasn't getting stuck on anything particular; I just wanted to know whether I was correct up to here (I'll edit or comment if I hit a roadblock again). |
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Jan 5 |
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Application of Heisenberg's uncertainty principle $k$ is varying with respect to $n$, right? And isn't $k=\frac{\pi n}{L}$, so why is its variance equal to itself? |
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Jan 5 |
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Application of Heisenberg's uncertainty principle Unless the variance of $k$ is linear wrt $k$, then it just seems to be missing a factor of $2$. |
