# All Questions

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### Conventional flux in centrifuge?

The molecules are sedimentated in centrifuge, which is rotating with angular velocity $\omega$. The chemical potential of molecule (considering potential associated with centrifuge force) is: ...
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### Number of States and Required Info for Bits vs Qubits

So with classical bits, if you have 2 bits, there are 4 possible outcomes that are possible. To determine these states, you only need 2 pieces of info, the state of each bit. With 3 bits, you can have ...
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### Electrolysis of Paramagnetic Ferrous Chloride in Water

I'm trying to settle a bit of a debate between a friend and myself over the cause of an effect observed when dissolving Ferrous Chloride, Iron(III) Chloride, in water and supplying an electrical ...
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### Tensor raising and lowering

Just a quick question. I know: $V^{a}V_{a} = 1$ But wondered on the following: $V^{a}_{ab}$ Is it $1*V_{b} = V_{b}$ Or would I have to re-label V as it wouldn't be the same component?? Thanks!
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### Friction Force and Applied Force for Acceleration

A person needs to move a 565 N object. The coefficient of static friction for the surface it's sitting on is 0.63. How much force is required to accelerate the object at an initial rate of 0.4 m/s2? ...
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### Problem with commutator

My area is mathematics; however, told me about a problem that can solve with simple math, it says: Using $[\hat{J_{z}},\hat{O}]$, show that $\langle\alpha,j,m|\hat{O}|\beta,j',m'\rangle$ can be ...
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### “Voyager: Lightning on Jupiter”: what's a sound source for this?

NASA created an official Soundcloud channel with a various sounds from missions. There are a Voyager: Lightning on Jupiter sound. Is there are ay information on how's this sound is produced (and ...
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### Why is the voltage negative?

What I don't understand is why the the two voltage sources are subtracted when working out the emf for part a, The graph does not show the orientation of the solar panel so I thought I was to ...
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### can there be an object which reflects( not illuminates ) electromagnetic waves in the non visible region?

can there be an object which reflects( not illuminates ) electromagnetic waves in the non visible region? If so then will it be appeared to us(humans who can see visible region only) transparent or ...
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### Calculate rotational duration of magnetic levitation inside a vacuum chamber?

Background Numerous examples show rotating pyrolytic graphite (or similar diamagnetic material) that can be moved using a laser. Problem The problem has the following objects: An N52 grade ...
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### What mechanism is responsible for the creation of these dunes on Comet 67P/Churyumov-Gerasimenko?

What mechanism is responsible for the creation of these dunes on Comet 67P/Churyumov-Gerasimenko? The following high resolution picture from ESA's Rosetta mission shows the dunes: At a distance ...
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### Alternating Current/Electromototive Force equaling 0?

All alternating current diagrams are drawn as sinusoidal waves that intercept with x axis. Given our usual sine wave that equals to 0 at 180° it would mean the alternating current would equal to 0. If ...
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### How does independence of the basic bras affect the choice of numbers used to represent a ket?

On page 54 of Dirac's book, The Principles of Quantum Mechanics, he states: Take an orthogonal representation with basic bras $\langle\lambda_1\lambda_2...\lambda_u|$, labelled by parameters ...
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### Extracting times of hits from a composite detector response

I have a detector that registers a sequence of "hits" over a period of time. Each hit produces a signal that has the approximate form ...
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### Sum of static and dynamic pressure in a tube constant?

The sum of static pressure and dynamic pressure is said to be constant along a streamline. Except for energy conservation reasons I don't understand why that is. Static pressure is proportional to ...
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### Principle of electrical machine by vk R mehta complete ebook needed [on hold]

I need the ebook for my exam on Wednesday(expecially dc generator and dc motor chapter)
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### Tensor Notation Puzzle

I have hesitated to ask this question for fear of someone tagging it as a duplicate. It comes close to what others might have asked but I am looking for particular answers to this puzzle. Using ...
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### Can we harvest energy from constant gripping?

Gripping things hard needs energy even though nothing really moves. So I think we could harvest energy from this action, but I know that any type of energy harvesting requires moving parts. So can ...
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### what is variable mass of earth or center of mass? [on hold]

If we say the human being follow the law of conservation of mass. I agree then billon year ago the earth mass was in its bength which has came above so that means either mass along with its related ...
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There seems to be some different standards on the indexes of the tetrad. I am wondering which is the standard, which is correct, and which is an abuse of notation. In Sean Carroll's notes and in ...
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### Water escaping from a pendulum bob, how is time period affected? [on hold]

well the question is: A hollow pendulum Bob filled with water has a small hole at bottom, through which water escapes at a constant rate. How is the time period(T) affected as the water flows out? I ...
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### What are the advantages of Magnetocardiography?

I am reading the book Bioelectromagnetism by Malmivuo: Difference between the bioelectric and biomagnetic measurements lies in the sensitivity distributions of these methods. Diverse technical ...
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### Is electricity constant in standard ECG device? [on hold]

I am reading the book Bioelectromagnetism by Malmivuo et al. I am thinking if you need to use Maxwell equations in electromagnetism of ECG device. I am not sure if you need to change the current ...
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### What is the physical meaning of anti-commutator in quantum mechanics?

I gained a lot of physical intuition about commutators by reading this topic. What is the physical meaning of commutators in quantum mechanics? I have similar questions about the anti-commutators. ...