# All Questions

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### How to calculate the function giving the angle of an oscillating axle?

Suppose we have a rod of length $r > 0$ and we attach to one end of it an object of mass $m > 0$. Also, we attach the second end to a static location. Finally, we are given a friction ...
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### Are Transmission values for absorptive light filters proportional to Intensity?

Mostly filter rates are given in percent, but if I imagine that for example 10 photons hit an absorption filter with 50%, molecules are excited there and in the end only 5 get through while the other ...
11 views

### Two space crafts A and B travel towards each other at 90% of the speed of light. What does A observe on B and B on A?

This is an extention to the "twin paradox". Suppose that two space crafts A and B travel towards each other at 90% of the speed of light. There is an observer C on earth. We know that from C'...
6 views

### Why is the electric field time independent in the induction equation of the magnetohydrodynamics?

Why does the induction equation of the magnetohydrodynamics assume the electric field $E$ is time $t$ independent or $\frac{\partial E}{\partial t}=0$?
14 views

### Depletion Region of PN junction

In the depletion region of the PN junction diode, charge carriers are negligible but there is charge density. How?
1 vote
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### Trying to derive chiral anomaly in 2D from Feynman diagrams in position space

Trying to understand the Chiral anomaly, I decided to explore the simplest example of a holomorphic fermion in 2D in a background electromagnetic field $A\text{d}z+\bar{A}\text{d}\bar{z}$. The ...
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### SOLID STATE (FCC LATTICE STRUCTURE) [closed]

How many atoms per mm2 surface area are there in (110) plane for lead which has FCC structure. The radius of atom is 0.74nm. I'm not able to proceed
31 views

### Different Bernoulli equation from $F=dp/dt$ [closed]

If any part of the question needs clarifying, there might be explanation in the post-script and of course ask if needed. I understand how the Bernoulli equation is derived for incompressible fluid in ...
18 views

### Consider an infinite solenoid in wich a sinusoidal current flows, is the potential energy stored inside the solenoid a conservative energy?

If it is not, could you still add this energy term in a Lagrangian ?
32 views

### Is my conceptual general theory model of The Universe as fundamentally micro-particulate possibly viable? [closed]

Suppose that at creation material particle mass was around 2 x 10^-87 and there were several types. That a large amount of material was expelled at below c, but then things got going and following ...
70 views

### How to know which states are entangled from a state vector?

consider the following state vector of three qubits $$(1/2)|000⟩+(1/2)|011⟩+(1/2)|101⟩+(1/2)|110⟩.$$ how to know which qubits are entangled with respect to their basis states, in other words, how do ...
103 views

### What kind of coordinate change is needed to make gravity disappear?

I understand that the Christoffel symbols associated with the metric will vanish locally once you perform the appropiate change of coordinates. These new coordinates correspond to an observer in free-...
103 views

### Superposition and Electrons

I was watching the following video here. It discusses the electron spin quantum number $m_s$. It then discusses that an electron may be classified as having spin up or spin down. From what I ...
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### Analyzing the angular frequency of an oscillating charged mass [closed]

A small puck of mass m carries a negative electrical charge –q. It slides on a frictionless horizontal surface, which is a distance a above a postiive charge +Q, as shown, so that the equilibrium ...
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### Difference in spin angular momentum

In chemistry, I learnt that the spin angular moment of a single unpaired electron in an atom can be calculated by $\frac{\sqrt{3} h} {4\pi}$, but while studying radioactivity, I studied that the spin ...
28 views

### Expressing a specific motion from the point of view of a different rotating coordinate system [closed]

Simplified problem presentation I am trying to describe a specific motion from a point of view of a moving coordinate system. To make easier the comprehension I created this childish animation, where ...
1 vote
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### QM from the uncertainty principle?

In a book Quantum Mechanics with Applications (1970) by D.B. Beard and G.B. Beard, the authors wrote on page 34: "By methods beyond the scope of this text, one could state the uncertainty ...
38 views

### Relationship between volume and temperature of an ideal gas

I am self-studying thermodynamics, and was reading up Carnot heat engine (Yunus Cengel - thermodynamics book). So, the experiment in the textbook is set up such that, we have an adiabatic piston-...
1 vote
92 views

### The Work-Energy Theorem in Non-Inertial Frames: A Critical Analysis and Misconceptions

It is evident from these queries and responses that the Work Energy Theorem holds true in non-inertial frames (with work performed by pseudo force included in the equation). Is work-energy theorem ...
25 views

### Minimising losses in an optical resonant cavity

I am doing a question and I am asked to calculate the radius of curvature of two identical mirrors at either end of an optical cavity in order to minimise the losses in the cavity. Is the correct ...
26 views

### Determine number of objects in box by shaking

Given a container filled with identical objects, how could I find the number of objects in the container accurately purely by analyzing the sound produced on shaking? More specifically, which acoustic ...
39 views

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### Is the electric flux from the antenna able to exist without connecting electric charge?

https://en.wikipedia.org/wiki/Radio_wave#/media/File:Dipole_xmting_antenna_animation_4_408x318x150ms.gif According to above figure, the electric flux is in the close loop state like a balloon and is ...
975 views

### Ground state of the Heisenberg XXX model with a coupling?

I have a one-dimensional Heisenberg chain with a Magnetic field with $N$ sites with $J>0$ \begin{equation} \mathcal{H} = -J \sum_{i = 1}^{N-1} \vec{S_i}\cdot \vec{S_{i+1}}- \sum_{i = 1}^N \vec{H}\...
1 vote
24 views

### Will a persistent supercurrent in a superconducting aluminum ring decay if the ring is connected to a non-superconducting aluminum wire?

Will a persistent supercurrent in a superconducting (SC) aluminum ring decay, if we connect the SC aluminum ring to an aluminum wire and the remote end of the wire is located in a separate chamber ...
48 views

Can then resultant vector pass through the vectors being added? Does the order in which place vectors according to head to tail rule matter? let's suppose that vectors A and B are pointing east while ...
42 views

### Where does the force that resists changes to an objects geodesic path in empty space come from?

assuming an object is free of a gravitational field and following its geodesic. Applying a force would be changing the 4 vector momentum of the object relative to the frame the object was in before ...
36 views

### Why don't they use golf ball dimples on cars? [duplicate]

Just watched an episode of mythbusters where they proved that a car got better fuel economy with golf ball dimples. So why don't they use that on cars?
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### Newton's second law - local laws and non-local laws

What are local laws? I was reading this line in a book... Newtons second law is a local law. This means that it applies to a particle at a particular instant without taking into consideration any ...
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### How does changing the mass of a block affect its speed after collision? [closed]

I'm doing a physics IA investigating how mass of a block affects it's velocity after collision when initial momentum is constant. I did this by using a pendulum setup with a constant release angle (...
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### How does QED describe the electromagnetic scattering between two neutral fermions?

Fermions with no electric charge may carry magnetic moments e.g., the neutron. Since particles with magnetic magnetic moments interact, they're expected to scatter off each other electromagnetically. ...
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### With respect to [closed]

e-mc^2. What is light in between. What type of essence is it before it becomes energy? How does it appear or does it, like an event horizon, suddenly change over?