# All Questions

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### Why is it useful to study spatially inhomogeneous spacetimes? [on hold]

There are many scholars who have dedicated their efforts towards finding solutions to the Einstein Field Equations that are spatially inhomogeneous. Current cosmological observations indicate that on ...
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### What do you actually mean by DC voltage again and AC voltage gain? [migrated]

What do you actually mean by DC voltage gain and AC voltage gain? I know their formulas but I do not understand what they actually are? That is, basically I do not understand what is their ...
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### What do you actually mean by DC current gain and a AC current gain in transistors [duplicate]

What do you actually mean by DC current again and AC current gain? I know there for formulas but I did not understand what actually they are , what is the significance. So basically I do not ...
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### How actually sign reversal of output signal and the input signal takes place in case of amplification of transistor? [migrated]

How actually sign reversal of output signal and the input signal takes place in case of amplification of transistor? I am a class 12 student so make me understand accordingly.
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### How do we know that supermassive black holes formed in the early universe?

Could they have existed from the very beginning? Could they be leftover fragments of the cosmic egg?
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### Why does small change in Base current causes a larger change in collector current in case of transistors? [on hold]

Why does small change in the base current causes larger change in the collector current. That is say if I increase the base current buy a small amount why the collector current increases by a very ...
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### In causal dynamical triangulation, what equation(s) give the distribution of angles of the triangles?

I know very little about this topic, but going on what I learned in my one semester of QM, there has to be some Schrodinger-like equation they are using to get the distribution of angles of triangles ...
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### What is beam confinement?

In the context of the propagation of an electromagnetic wave and optical vortex solitons, I came across the term "beam confinement". Particularly, beam confinement requires the amplitude of the ...
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### Mutual or same set of eigenfunctions if two operators commute

If two operators commute, do they have "a mutual set of eigenfunctions", or "the same set of eigenfunctions"? My quantum chemistry book uses these as if they are interchangeable, but they do not seem ...
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### Formulae for Elastic Hysteresis of rubber

Being a school student, I'm pretty sure we don't need to explicitly learn any formulae helping us evaluate the energy dissipated by mechanical internal energy in a hysteresis loop. But I was wondering ...
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### To what height does the ball rebound and what is the velocity of the struck block after impact? [on hold]

Here is the problem. I have tried it four different times, and I will show my most recent work. [![enter image description here][3]][3]
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### What happens if an object stops orbiting the sun? [on hold]

What would happen if an object (like a space ship) was to stop its orbit around the sun. would time slow down with that object (the same way time sped up for the characters in that great film ...
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### Air flow speed and penetration abilities

As I understand, two fans with the same diameter and with the same rotor speed(usually measured in RPM) can have different air pressure(usually measured in mmH2O) and air speed(usually measured in ...
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### Modeling Fluid Flow

I could really use some assistance. How would I go about trying to use Maple in order to model flow of a fluid through objects? For a rough example, such as entering an enterance of a maze and exiting ...
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### General Solution to Linear Schrodinger equation

I am trying to find a solution to $$\displaystyle \left[-\frac{1}{2}\nabla^2 - \frac{2}{r} + C(r)\right]\phi(r) = E\phi(r)$$ where $C(r)$ is a known function of r. I am just looking for some help on ...
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### How bicycle gear works?

Based on the concept of the moment of inertia, my book gives the following relationship between the size of gear and amount of torque supplied to the drive wheel: Because it [outermost gear] had ...
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### Volume integral of pressure interpretation

If you have a fluid with with pressure field $p$ what is the physical significance of the the volume integral of the pressure $\int_V p dV$?