# All Questions

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### Basic rotational kinetics problem

We wrap a light, nonstretching cable around a 9.00kg solid cylinder with diameter of 26.0cm . The cylinder rotates with negligible friction about a stationary horizontal axis. We tie the free end ...
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### Are continuous mathematical models of discrete physical phenomena messy because of a disconnect between “continuous” and “discontinuous”?

A copy of my question on Mathematics: Examples from statistical mechanics and continuum mechanics abound: a discrete phenomenon (e.g. kinetic energy of molecules) is "averaged" out over the ...
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### Find normal force [on hold]

The information is in the picture. I have to find the normal force on the 5.0kg block, but I do not know how. Can anyone give me the formula or any tips to find the normal force on the 5.0kg block? ...
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### Using the boundary states, is there a precise way to write down a planar open string multi-loop amplitude as a closed string tree amplitude?

The only explicit computation I have seen is the planar 1-loop one, but there should be a way to write the multi-loop case in terms of boundary states as well.
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### Physics of foreskin, cylinder or ellipsoid?

I asked this question over at Math, but it was deleted. I am having an argument with some of my friends. For the sake of this question let's accept that the foreskin can be expanded with tension and ...
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### Large-N critical NLSM

Is this in general true that the large-N critical NLSM on a manifold $M$ is the same as the theory of $N$ non-interacting conformally coupled scalars on $M$? Or in otherwords - will the Lagrange ...
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### Relating Schrödinger's Wave Equation and Heisenberg Uncertainty Principle

A homework question that I don't conceptually understand: A quantum particle of mass M is trapped inside an infinite, one-dimensional square well of width $L$. If we were to solve Schrodinger's wave ...
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### Are leptons, baryons and energy the only products of radioactive decay?

I recently visited my child's elementary school to speak to a science classroom about rocks and minerals. While trying to explain what a crystal is, I got sloppy and mis-spoke that an atom was the ...