0
votes
1answer
36 views

How do we find the cone angles of the conic sections that are the Newtonian orbits?

In planetary motion, when the eccentricity of a conic section and its semi-latus rectum are known, how do we find out the cone's semi-vertical angle and angle of cutting of the cone by plane?
0
votes
1answer
31 views

Reference for passive scalar

I would like to learn about turbulence of a scalar advected by a random velocity field. I know that this problem can be solved analytically and that the statistics of the scalar field are ...
0
votes
0answers
26 views

What is the work-function of a monolayer metal on a substrate with charge redistribution at the interface?

The work-function on subsrate/metal with nm thick (or above) metal layer generally reveal the intrinsic work-funtion of bulk metal. But what if there is a monolayer thick metal, and there is charge ...
0
votes
0answers
19 views

At the speed of light [duplicate]

Is it possible to accelerate a body to the speed of light?Why is is said that at the speed of light,the mass of a body would be converted to energy?
0
votes
1answer
42 views

What is the dimension of the solution for Laplace's equation between two cylinders?

Calculate the $\phi$, satisfying $\nabla^2 \phi=0$ between the two cylinders $r=a$, on which $\phi=0$, and $r=b>a$, on which $\phi=V$. I calculate it and found the solution is ...
0
votes
0answers
51 views

How does one find the phonon frequencies for a 1D anharmonic interaction potential?

Suppose there is a one-dimensional crystal with an anharmonic interaction potential between particles (e.g. $U = ax^2+bx^3$ where $x = d-a$ with $d$ as the distance between two particles and $a$ as ...
0
votes
0answers
39 views

Scattering Amplitude Not Invariant under Little Group?

I am trying to make sense of scattering amplitude recently. In some literature people say that if some number of massless particles collide together, one can theoretically express the scattering ...
0
votes
0answers
23 views

Formula for computing macrostates

I'm trying to figure out how to arrange 3 particles across 5 energy level from 0E to 4E and obtained 5 macrostates (this could be wrong). While it is possible to do so for small number of n particles, ...
0
votes
2answers
38 views

What theories or formulas are involved with velocity

What theories or formulas are involved or can be added as background information in an experiment that sees a small toy car roll freely down an incline where the surface area is altered to cause more ...
0
votes
2answers
53 views

Why are magnets made in only a few shapes?

Additionally, why are all magnets solid? For example, why can't a magnet be made in the shape of a PVC pipe (very long tube)?
0
votes
0answers
47 views

Question about DC & AC Generators

Main question: moving a alternating magnetic field past a coil can create AC, if the same pole is moved past repeatedly does this still generate the same amount as the AC version would? or is the ...
0
votes
1answer
20 views

the different settling speed of two solid particles in fluid

In a container full of fluid A, which can be water or oil, I have two solid particles, both of which are of the same material. These two particles are of different size. One is bigger than the other ...
0
votes
0answers
50 views

Free particle scattering in 2D using polar coordinates

The free particle hamiltonian commutes with the angular momentum operator L and Lz, so we can use a spherical wave basis instead of the regular plane-wave basis |k>, using spherical Bessel function ...
0
votes
0answers
40 views

What is the largest atom with a reliable configuration-interaction (CI) calculation?

The simplest approximation for calculating the ground state of an atom is the Hartree-Fock approximation. To get accurate result for the ground state energy, one has to do configuration-interaction ...
0
votes
0answers
37 views

Compression in a sphere due to a sectoral load?

I wish to know the net compression in a solid and hollow sphere when a radially perpendicular load is applied on a sector of its circumphery. Ex: on 2(pi)r/8 of the circumference. thanks
0
votes
0answers
61 views

Kähler Potential of Calabi-Yau volume

At tree level, the Kähler potential is given by (neglecting complex structure) $K = -\ln(-\mathrm{i}(\tau - \bar{\tau})) - 2\ln(V_{CY})$ where $V_{CY} = \frac{1}{6} \kappa_{abc}t^at^bt^c$ ia the the ...
0
votes
0answers
28 views

Functions of the form $F(x-ct)$ written as superposition?

In this section of the Wikipedia article on the wave equation they do the following: $$\int^{\infty}_{-\infty}s_+(\omega)e^{-i(kx+\omega t)}d\omega +\int^{\infty}_{-\infty}s_-(\omega)e^{i(kx-\omega ...
0
votes
0answers
29 views

Q: Any standard terminology for “gold standard” Monte Carlo solutions

The "standard" way in our field to compute scattering statistics in wave propagation problems is via a "deterministic" wave prop code operating in a Monte Carlo context where we iterate over many ...
0
votes
1answer
59 views

Why the electrons flow from higher potential to lower potential?

We know that every thing moves from a higher potential to lower potential. In fact we also studied in our textbooks that a charge travels from higher potential ie. Positive side to lower potential ie. ...
0
votes
1answer
35 views

How can we know that a particular charge is positive or negative?

Suppose I am provided with a positive is charged....and someone tells me to find which type of charge is present in it? Then how can we detect that the body is positively or negatively charged? Is ...
0
votes
1answer
57 views

Where does this hyperbolic tangent in Nakahara's text come from?

I don't see why the term with $\tanh$ appears in the equation 1.164 The textbook is the second edition of Geometry, Topology and Physics
0
votes
0answers
43 views

Why are the azimuthal quantum number $\ell$ and magnetic quantum number $m$ integers? [duplicate]

Why are the azimuthal quantum number $\ell$ and magnetic quantum number $m$ integers?
0
votes
0answers
43 views

The Lie algebra of the Lorentz group is $su(2) \oplus su(2)$. Is there a similar relation for the algebra of the Poincare group?

It can be shown easily, by introducing new generators from the usual ones that we can think of the Lie algebra of the Lorentz group as being built up by two copies of the $SU(2)$ Lie algebra: $$ ...
0
votes
0answers
62 views

Unitary evolution operator

Assume we have a system in a state $\psi$ that is a superposition of eigenvectors of some observable $A$. Now we make a measurement of the observable $A$; the state after the measurement $\phi$ is a ...
0
votes
1answer
78 views

The general equation for a wave packet derivation? [closed]

On Wikipedia it gives the general equation for a wave packet (and therefore for a wave?) to be: $$u(x,t)=\frac{1}{\sqrt{2\pi}}\int^{\infty}_{-\infty}A(k)e^{i(kx-\omega t)} dk$$ I have been trying to ...
0
votes
0answers
60 views

Construction of free energy based on Landau theory

Consider an Ising model system where the total energy is $E = −J \sum_{<ij>} S_iS_j $, $S_i = \pm 1$ and $< ij >$ implies sum over nearest neighbours. For $J < 0$ the ground state of ...
0
votes
0answers
30 views

Infinite force between two point charges as $r$ approaches 0 [duplicate]

According to coulombs law the Force experienced by two point charges increases with the inverse square of their separation. This would imply that at distances approaching 0, the Force approaches ...
0
votes
1answer
44 views

Do/May pure electromagnetic waves ( Non dual natured ) exist?

The light as well as all matter 'particles' show dual nature. But my question is if according to the Maxwell equations, Electromagnetic waves are valid events, can they actually exist in pure wave ...
0
votes
2answers
406 views

How does temperature relate to the kinetic energy of molecules?

In ideal gas model, temperature is the measure of average kinetic energy of the gas molecules. If by some means the gas particles are accelerated to a very high speed in one direction, KE certainly ...
0
votes
0answers
13 views

Why is forward brillouin scattering difficult to observe?

Generally we talk of only the backward Brillouin scattering. And I just know forward scattering is difficult to observe? Why is it so? Does it have something to do with phonon life time? Is it ...
0
votes
2answers
65 views

Why doesn't current induced by changes in flux affect the flux, while current induced by a battery does?

Faraday's law states $V=-\frac{\mathrm{d}F}{\mathrm{d}t}$, where $F$ is flux. Since $V=IR$ for passive circuits, $I = V/R = -\frac{1}{R}\frac{\mathrm{d}F}{\mathrm{d}t}.$ But by the Biot-Savart law, ...
0
votes
1answer
37 views

Counting the number of microstates that there are for a given configuration. How to prove this result?

I'm doing some statistical physics and I came across a result which I'm not sure how to derive. Any help? The answer turns out to be: Can anyone help with this derivation? Thank you :D
0
votes
2answers
84 views

How is the work done by a system turned into internal energy according to the first law of thermodynamics?

I have several questions about the first law of thermodynamics: When we have a force over a piston of a recipient with an ideal gas inside and that piston moves, we have work associated with that. ...
0
votes
0answers
77 views

Variation on the “Hole through the Earth” problem

In the news recently was the announcement that the answer to the classic Newtonian mechanics question of the time it takes for a body to fall all the way through the Earth was corrected to account for ...
0
votes
3answers
123 views

The correct integral for Newton's shell theorem

I am trying to prove Newton's Shell Theorem, and the natural integral I think of to use does not seem to give the right answer, so I am trying to find my mistake. For simplicity, I will work in one ...
0
votes
0answers
19 views

How does the phase of an alternating current change when flowing through a multi-layered material?

I have questions regarding the properties of the alternating electrical current in the following imaginary experiment: There is an AC (sinusoidal wave with frequency $f = 5\ \mathrm{Hz}$). I would ...
0
votes
0answers
15 views

Magnetic anisotropy

Magnetic anisotropy is a prerequisite for hysteresis in ferromagnets: without it, a ferromagnet is superparamagnetic. Is this correct? I think even magnetically isotropic material can have hysteresis ...
0
votes
0answers
14 views

Rotating conical singularities in three dimensional gravity

A conical singularity in three dimensional flat space is usually desrcibed by the metric $ds^2=-dt^2+dr^2+r^2\gamma^2d\phi^2$ In three dimensional gravity with a negative cosmological constant, we ...
0
votes
0answers
13 views

Ionic relaxations in DFT

I have just started learning DFT for a research project and I have a question about allowing ionic/geometric relaxations. My understanding of the Kohn-Sham equation is that the self-consistency loop ...
0
votes
0answers
56 views

How many quantum fields are there?

I'm just an aficionado, but my understanding is that in QFT, the photon is an excitation of the electromagnetic field, the electron is an excitation of the electron field, and so on. Is there a ...
0
votes
3answers
85 views

Event Horizon of Black Hole

What actually does happen to an object after it crosses the Event Horizon of a BH? Does it- lose the properties of matter and become a new, undiscovered type of matter? does it become negative ...
0
votes
0answers
69 views

Are there any good books about Grand Unified Theories?

I'm starting to get a little desperate, because I can't find any introductory treatments of Grand Unified Theories (GUT). So far the only books I found are Mohapatra Unification and Supersymmetry ...
0
votes
2answers
42 views

What the wave function looks of a particle in the infinite square well looks like after collapse for measurements of position and energy

Consider a particle in a the infinite square well from x=0 to x=L. At t=to, I make a measurement of position and get x=L/2. What is the resulting wave function at t=to? My understanding, from reading, ...
0
votes
1answer
25 views

plasma and infinite acceleration

I am trying to set up a simulation of particles (they are not any particular kinds of particles, they are just points that repel each other). All the particles repel each other through the inverse ...
0
votes
0answers
66 views

Total Energy of Inverted Pendulum

I have to find the total energy $V$ of an inverted pendulum (rod). The following parameters and their values are given: Mass $m$ and length $l$ of the pendulum $\theta$ as the angle of the ...
0
votes
0answers
43 views

Physical interpretation of legendre transformations in thermodynamics

I have found this question(Physical meaning of Legendre transformation) and I have some questions regarding the transformations in thermodynamics, In thermodynamics we have: $$H= U+PV $$ $$F=U-TS ...
0
votes
3answers
56 views

How does $p=fv$ hold when $v=0$ and an engine is working?

Standard high school equations: Work = Force x Distance Power = Work / Time = Force x Distance / Time = Force x Velocity When a space rocket takes ...
0
votes
0answers
43 views

Another universe in the other side of a black hole? [duplicate]

A common notion is that there is another universe in the other side of a black hole, past the singularity point....is this true? does it have any scientific support?
0
votes
0answers
30 views

XRD of Graphene Foam

At what 2$\theta$ values Graphene Foam shows the peaks in XRD ? I got two peaks at 2$\theta$ values 14.7 degree and 17.2 degree..
0
votes
2answers
89 views

Approximating energy loss caused by drag force

We know the usual aerodynamic drag equation is given by: $$F_d = -bv^2$$ Where $b$ here is just some constants combination related to the property of the fluid and the material passing through. My ...

15 30 50 per page