# All Questions

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### Poisson equation solver with specific boundary condition

I want to solve 2d Poisson equation with this Boundary conditions below $$u(-5,y) = 0 , \\ \frac{\partial u(x,y)}{ \partial x} = 0 \,\,{\rm at}\,\, x = -5\\ u(x,-5) = u(x,5)$$ Now my question is ...
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### What could be the use cases of optics in a computer algebra system? [on hold]

I am working on optics module in sympy. As of now I've only implemented Transverse wave, Medium and some functions for ...
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### The physical definition of work seems paradoxical

So this is possibly a misunderstanding of the meaning of work, but all the Physics texts, sites, and wiki that I've read don't clear this up for me: In the simplest case with the simplest statement, ...
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### What are quasars?

I was taught that apart from stars, the other self illuminating objects in the universe are quasars. What are quasars? It seems the definition of a quasar is an active galaxy? What is that and how ...
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### Is it possible to go to graduate school in physics with a different undergrad degree? [on hold]

Specifically, a major in mathematics or applied math, while self studying the undergraduate physics curriculum, as I also want to major in computational biology. A triple major would make it difficult ...
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### Why does a minor vertical vibration cause my coffee to spill?

When I walk my kid sometimes I put a cut of coffee in a cupholder attached to the stroller. When I push the stroller over a brick pavement it seems to vibrate vertically. That is enough for the coffee ...
81 views

### Action and Action integral: Different kinds of variational principles

What are the difference between: the action $\int_{t_{1}}^{t_{2}}(L+H) dt$ that we use in the principle of least action, and the action integral $\int_{t_{1}}^{t_{2}}L dt$ that we use in ...
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### Basics of Current Electricity

I have certain questions which confuse me a great deal. I want to have a very basic and clear idea about some concepts. Here it goes: 1) I am really confused on how a battery actually works. The very ...
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### Introductory derivations of Heisenberg uncertainty principle

I'm not an expert when it comes to quantum mechanics, so correct me wherever I'm wrong, but: I've always been a little bit bothered by introductory derivations of the Heisenberg uncertainty relations ...
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### Why does blowing on hot coffee cool it down?

And will it cool off faster if you blow across the top of the cup or directly into the coffee? Does it have to do with the fact that when you blow across the top of the cup the velocity of the air ...
9 views

### How to survive a lightning strike [migrated]

Is this really a plausible way to survive a lightning strike ?
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### Calculate Power requred to rotate a certain disk at a specific RPM in different conditions [on hold]

I have two acrylic disks with $x$ radius and $y$ thickness. I want to rotate that disk at certain RPM using a Motor. I know the weight of the disk. the weight of the Disks are virtually uniformly ...