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According to Wikipedia
In physics, work is the energy transferred to or from an object via the application of force along a displacement.
But for a gas in a closed vessel with movable massless piston, what would they do work on? Since the piston is massless, the energy will not be transferred to it, where would the e... |
Since the BRST charge operator commutes with the Hamiltonian of QCD, a physical state such as $q+\bar q$ should not be allowed to evolve into an unphysical one like $\chi+\bar\chi$, where these two are the Faddeev-Popov ghost and antighost introduced for the gauge-fixing of the theory. In other words, the amplitude of ... |
My textbook says the absolute refractive index of a medium $$n = \dfrac{c}{v}$$
where $c$ is the speed of light in vacuum and $v$ is the speed of light in the medium.
Why hasn't it been chosen the other way round i.e. $n = \dfrac{v}{c}$?
|
There is this newly discovered zeptosecond discovered by scientists. I have seen some articles calling it smallest unit of time ever measured. How can it be possible if Yoctosecond already exists which is smaller than it.
Can someone explain this?
Here are links to some of the articles:
BBC News: Zeptosecond - the smal... |
This problem (the b part) asks me to find the acceleration of the blocks but I'm quite not able to understand 2 thing
1.how the change in direction of F will cause the change of acceleration.
How to judge whether kinetic or static friction is operating
I dont want the solution for it but the basic idea of how the ch... |
What will happen to the height of the Mercury column of a barometer when the barometer is accelerated upwards assuming the value of g does not change with height?
I think the height will remain same because the weight of Mercury will increase just as weight of block increases in an upward accelerating lift and the pr... |
Could one reasonably strong person move a floating aircraft carrier?
(EDIT: World's Strongest Man? [1])
Assume perfectly calm water; no ocean waves at all.
Say, by pulling it with an attached rope, or pushing on it.
https://en.m.wikipedia.org/wiki/World%27s_Strongest_Man
|
I try to calculate the elastic constant tensor for some organic molecular crystals.
There are plenty of accounts in the literature where people do that, using atomic
resolution models and DFT, EAM, or classical empirical force fields. A popular
way of getting the result from that is by deforming/shearing the unit (or s... |
I was reading a text on "The Speed of Light in a Moving Medium"(topic in Special Relativity from Introduction to Mechanics by Kleppner and Kolenkow). They derive the expression for the speed of light in a laboratory frame that is passing through a moving medium of refractive index $n$. In the end, they found that speed... |
I see that the current before and after a Resistor is the same. I want to prove this with the Drude-Lorentz model.
The situation is like this
I put the Ammeter before the resistor and I measure k1 Ampere. I put the Ammeter after the resistor and I measure k2 Ampere.
I experience that k1=k2.
My model view is like this ... |
In studying statistical mechanics, we ran into the concept of 3-body potentials, and in general $n$-body potentials. For $N$ interacting spherical particles in a closed volume $V$ in $d$-dimensional Euclidean space $\mathbb{R}^d$.
Let $\Phi _N(r^N)$ be the N-body potential for particles with configuration $r^N=r_1,r_2,... |
Ampère's law is stated as
$$\nabla\times\vec{B}=\mu_0\vec{J}.$$
I am told this only works in steady currents and not with time varying ones.
However Maxwell's addition of $+ \mu_0\varepsilon_0 \frac{\partial\vec E}{\partial t}$ means that this works for a time varying current.
Why in the case of a steady current does t... |
I've solved many problems calculating the electric field, $E$, of a given charge distribution but I'm just musing a bit as to why this is useful. The definition of $E$ involves the force, $F$, on a test charge, $q$, and the ratio $F/q$ in the limit as $q-> 0$. So if we have an $E$ field and place a non-zero charge in i... |
Imagine a spherical planet with no atmosphere. A ball is launched radially with a velocity $v$, maintaining $\frac{v_e}{\sqrt2}<v<v_e $ and there is no other objects in the universe (Ideal two body problem.)
My question is, will this projectile orbit the planet? Note that, the projectile is launched radially.
As far as... |
I am taking graduate quantum mechanics, and we are now discussing the WKB/semiclassical approximation. I am trying to solve a problem where I would need to find the energy spectrum of the 1D motion in the following potential,
$$V(x) = V_0\cot^{2}\left(\frac{\pi x}{d} \right),\, 0<x<a.$$
I understand the fact that I wo... |
*The angle between the line from the earth to the sun and the line from the mars to the sun RIGHT NOW.
I only found the right ascention and declination of Mars, which is measured with respect to Earth. However, I am a bit confused about the March equinox, so I am not sure how I can deduce the angle I am looking from fr... |
Is this possible or not, and how do you know?
I am taking the convention of time being from left to right.
|
I have been reading literature on fuses and came across the joule integral or $i^2t$ value many times. Often, it is referred to as energy but I am confused because shouldn't energy be $E=RI^2t$? I would appreciate if you could explain what the joule integral is and its physical meaning.
|
A point P at the exact half way of two opposite charge will have zero potential (assume potential is set zero at infinity) ,but the electric field will not be zero at point P. How to completely explain this? What is the different to $E=-\nabla\ V$ and why?
|
Hi have been following an introductory course on quantum gravity and we are covering the basics of free quantum field theory in curved spaces.
I have been introduced to how spin connections play a role in the covariant derivatives of spinorial objects but only lightly.
The issue is that the course I followed in General... |
Fermis golden rule, derived from time-dependent perturbation theory, give the rate for a quantum system, disturbed by a weak harmonic pertubation with frequency $\omega$, to transition from a state $|i\rangle$ with energy $E_i$ in a continuum of states with energy $E_f+dE=E_i\pm \hbar \omega +dE$
$$
W_{i\rightarrow f}=... |
According to this website and this website, there are two mechanisms by which sound is absorbed in air: effects of viscosity and molecular relaxation.
According to Wikipedia, Stokes's law of sound attenuation is said to describe "the attenuation of sound in a Newtonian fluid, such as water or air, due to the fluid's vi... |
In the derivation of the Hamiltonian of a Cooper Pair Box, it is stated that the junction phase difference variable $\delta$ and the charge number variable $N$ satisfy the canonical commutation relation $[\delta, N] = i$. I don't understand why this is the case, and was wondering if there was a physical explanation for... |
My understanding is that the Hartree-Fock equations can be derived from the variational theorem as follows:
The variational theorem states that for an arbitrary wavefunction $|\psi \rangle$, $\langle \psi | H | \psi \rangle \ge E_0$, where $H$ is a Hamiltonian operator. Take then a specific kind of wavefunction that ca... |
The postulates of the special theory of relativity say that there is a limiting speed - the speed of light. But this is a postulate. There are experiments confirming that the speed of light is approximately $3 * 10 ^ 8 m / s$. From what fact does the finiteness of signal propagation come from? All theories, whether it ... |
I do understand qubits entanglement, and their spins but I do not understand that at circuit level how can we entangle 2 qubits? Is it related to 2 qubits gates?
|
I'm doing work for an intro space flight class, and I have to calculate the amount of fuel I need to get sizable a space craft, around 200 thousand kg in dry mass, into a transfer orbit from the surface of Mars.
Problem is, when I plug it into the rocket equation, I get a requirements of 900 BILLION KG OF FUEL. Am I mi... |
People often like to think that given a certain probability of a dataset explaining results, like say 90%, then it implies if you "reran" events 10 times, 9 times they would return the same outcome.
From a classical view this is not the correct interpretation since the results leading up to the event in question have a... |
When we are studying the Einstein solid, it is said that each solid has $N$ number of oscillators, but my doubt is what does it means. Are oscillators atoms? Or degree of freedom of each atoms? For example, an atom has four oscillators, what does it means?
|
Consider a situation where there's two springs, basically like this
Except vertically. Turn the picture 90 degrees (I couldn't find a good picture quickly). So the top spring has spring constant $k_1$, bottom one $k_2$, both have natural length $l$, the total length in the picture is $2l$. Let's say we pull it down by... |
I was reviewing my quantum mechanics notes, and I was confused on what this expression meant:
$$
|{\psi}\rangle = \sum_{i}|{\omega_i}\rangle\langle{\omega_i}|{\psi}\rangle
$$
I understand that it's creating a sum of $n\times n$ matrices, where each matrix contains a single 1 and the rest zeros, and when the product is ... |
In deriving the Josephson Effect, the ansatz wavefunction is given as $\sqrt{n} \exp{(i\delta)}$ which leads to the Josephson Relations. It seems that this wavefunction is used because $<\psi|\psi>$ should give the particle density. My question then, is that this ansatz wavefunction doesn't seem to be limited to superc... |
The Lagrangian in general relativity is written in the following form:
$$
\begin {aligned}
\mathcal {L} & = \frac {1} {2} g ^ {\mu \nu} \nabla_{\mu} \phi \nabla_{\nu} \phi-V (\phi) \\
& = R + \frac {16 \pi G} {c ^ {4}} \mathcal {L} _ {\mathcal {M}}
\end {aligned}
$$
with $g^{\mu\nu}: $ the metric
$ \phi: $ non-gravitat... |
While studying black-body radiation, I saw that most of the textbooks and videos I watched mentioned that there was a contradiction between the classical model of black body radiation and experimental data, which created the ultraviolet catastrophe. They all said that the classical model predicted continous increase i... |
For a three qubit-chain in a connected state barrier tunneling captured in the Hamiltonian below with J=1, U=3.
How do I fin J' when sites 1 and 3 decouple from each other?
|
It is said that most of theories, the even elements of the superalgebra correspond to bosons and odd elements to fermions (but this is not always true; for example, the BRST supersymmetry is the other way around)..
Why BRST supersymmetry is the other way around: odd elements of the superalgebra correspond to bosons a... |
Mercury is 15 329 km in circumference. Pluto is 7 232 km in circumference. Callisto is 15 144 km in circumference.
So why is it that Mercury is considered a planet and Pluto was once considered a planet, but Callisto is not considered a planet?
|
This follows a comment to split to a 2nd question Superalgebra and BRST supersymmetry 1: odd vs even
It is said that most of theories, the even elements of the superalgebra correspond to bosons and odd elements to fermions (but this is not always true; for example, the BRST supersymmetry is the other way around)..
Is ... |
Into the following part below, I don't understand what is precisely a "four-dimensional volume form" implied in the integral below:
For comparison, the Lagrangian defining general relativity is
$$
S=\int d^{4} x \sqrt{-g}\left(\frac{R}{16 \pi G}+\mathcal{L}_{\mathrm{M}}\right)
$$
where $g$ is the determinant of the met... |
The path integral with antiperiodic fermions (Neveu-Schwarz spin structure) on a circle of circumference $\beta$, in a theory with Hamiltonian $H$, has partition function
$$ \rm{Tr} \exp(−\beta H)$$
The path integral with periodic fermions (Ramond spin structure) has partition function
$$
\rm{Tr} (−1)^F \exp(−\beta H).... |
I am trying to understand some concepts related to scattering in QED, so I would phrase my question in similar context.
After calculating the scattering amplitude $\mathcal{M}$ for a process, we take its square for finding differential cross-section. But it seems that we need to trace over all the matrices involved in ... |
Concerning the Feynman-Hellmann theorem can someone point me on how solve this:
If $H E = E |E\rangle$ and assuming $H$ is depending on a variable $\lambda$ eg., $H = H(\lambda)$ then
$\langle \frac{\partial H (\lambda)}{ \partial \lambda} \rangle = \frac{\partial E (\lambda)}{ \partial \lambda}$.
And states of $H$ are... |
Book: General Relativity by Robert Wald (pgs: 342-343)
He starts out by suggesting that observers in general relativity correspond to orthonormal basis fields on the manifold, which I am OK with. However, on pg 343 he seems to suggest that a non-orthonormal basis doesn't correspond to any "physically realizable family ... |
How can we divide the whole matrix into submatrices that we can write effective Hamiltonian on the Heisenberg model Based on Fundamentals of the Physics of Solids book (Volume I) written by Jen˝o Sólyom, in chapter 14, page 464, (14.2.5) equation?
$H_{eff} = E_s + (1/2) (E_t - E_s ) S_{total} ^2$
$S_{total} = S_1 + ... |
I dont understand the second graph below. If I understand the first one right, it represents the potential energy between two atoms. So if we bring them closer together or separate them past the equilibrium we need to add energy.
But what does this graph below describe and what are those "zoomed in" lines of the grap... |
In Sean Carroll's Spacetime and Geometry book, pg. 22, it was stated that a (1,1) tensor acts as a map from vectors to vectors:
$${T^\mu}_\nu: V^\nu\rightarrow {T^\mu}_\nu V^\nu.$$
I tried showing this myself by considering the action of the $(1,1)$ tensor $T$ on a vector $V$:
$$T(0,V)={T^\mu}_\nu e_\mu\otimes e^\nu(0,... |
I'm confusing with a problem.
Consider an ideal inductor with a shorted circuit and no resistance and having a current through it. we know this current is constant while the inductor has no resistance because of its formula
The magnetic field of this inductor produces a force on a nearby iron block and pull it.
this ac... |
I am concerned about the accuracy of some information in a science textbook which I would like to clarify please. When white light is shone through a blue filter, only blue light will pass through. When the emergent blue light is passed through a red filter, no light gets through, because there is no blue light left. ... |
From Maxwell's curl equations, obtain the particular differential equations for the case of
$\vec{J} = J_z(y,t)\hat{z}$.
The solution provided for this question shows something like this:
$\begin{vmatrix}
\vec{a_x}&\vec{a_y}&\vec{a_z}\\
0&\frac{\partial}{\partial y}&0\\
{E_x}&{E_y}&{E_z}\\
\end{vmatrix} = -\frac{\parti... |
We can practically consider that the microscopic interactions are symmetric with respect to time(as we can neglect weak force for many cases which is the only interaction that can violate $T$ symmetry). So I thought that the asymmetry might be due to the irreversibility of quantum measurements. But this is only applica... |
Dear fellow physics lovers,
After having spent some significant time to understand the Lorentz Transformations the following is the most simple and complete single sentence definition of it that I have been able to think of.
A Lorentz Transform (also known as a Lorentz Boost) are a Set of Linear Equations that Transfor... |
I don’t know much about General Theory Of Relativity but I have heard that it does not consider gravitational fields like Newtonian Mechanics.
If an object were to be free falling, then according to general relativity that object would be in an inertial frame and everything around it will be accelerating at g rate.
So,... |
(1)In measuring time period of a pendulum, it is advised to measure the time between consecutive passage through the mean position in the same direction. This is said to result in better accuracy than measuring time between consecutive passage through an extreme position.
EXPLANATION: The speed near the extreme positi... |
My doubt stems from the question attached.
If some kinetic energy gets converted into spring potential energy, shouldn't the velocity of be reduced and subsequently momentum?
I also considered the second block to move due to the spring but then the spring would still have some potential energy and thus the velocity i... |
Hey I'm trying to build a toy model of gravitational radiation for fun from M theory.
I need some general help with selecting thru the ideas I have.
My first "model" is to make a M2 brane with gravitational charge on each brane. The string tension would then be my gravitational potential. Using dualities and the symmet... |
The emissivity of a gray body is constant but is considered to be less than 1. Since the black hole is considered near perfect black body but not a perfect black body its emissivity will be less than one hence can it be considered as a gray body?
|
A permanent cylindrical magnet with diameter $D$ and length $L$ possesses an uniform magnetization $\mathbf{M}$ going in the $z$-direction in a cylindrical coordinate system. The magnet is placed with its centre in the origin, with its length going along the $z$-axis.
Problem
Given the expression for the magnetic fiel... |
a mass of 10kg is maintained at 1m above the ground for 25s. What is the work done during this time interval?
i know this formula :
$ W = F * d * cos(a)$
but I don't find a formula with the time and i'm sure that if the time was 50s it will be more of work.
|
I am a bit confused about laser cooling an atom in all three dimensions. I think I have understood the one-dimensional case: The atom absorbs doppler-shifted laser light and the momentum in this direction is reduced by the photon's momentum $p_{\gamma}$. When the excited state decays, the atom re-emits the photon in a ... |
The symbols for Volt and for voltage are both $V$. Usually, the meaning of $V$ is clear enough from context to avoid confusion. However, I find a bit odd when both $V$ appear in the same formula. For example:
$$V=I \cdot R={10A} \cdot {5 \Omega}=50V$$
Is there an international standard how to write that more clearly?
I... |
I'm reading Merzbacher's Quantum Mechanics and he states the above (for analytic $F$).
To prove this, I could come up with the following, but am not sure if the last step is quite correct.
We have
\begin{align}
F(i\nabla_{\mathbf k'}, \mathbf k)\Big|_{\mathbf k}\left\{ \phi(\mathbf k') \right\}
&= \frac{1}{\left(2\pi\r... |
Is it just the spectrum of emitted photons that is broadened by e.g. finite lifetime or Doppler effects, or is it actually the electronic energy spectrum?
In my head it would only make sense if it is actually the energy spectrum itself.
|
This is from Zee's book on General Relativity. This is from Book 1, Part 1.6, on he bottom of page 89 as a "fun exercise".
Using
$$g_{\mu\nu}=\delta_{\mu\nu}+B_{\mu\nu,\lambda\sigma}x^\lambda x^\sigma+...$$
$$x^\mu=x'^\mu+M^\mu_{\nu\lambda\sigma}x'^\nu x'^\lambda x'^\sigma+...$$
I'm supposed to be able to find the cur... |
I have given the cyclic shift operator $X(x) \in \mathbf{R}^{d \times d}$, the generalized pauli operator, for a qudit system. This operator is defined by the action it takes on an arbitary ket vector $\left| j \rangle \right. \in \mathbf{R}^d$ with: $$X(x) \left| j \rangle \right. = \left| x \oplus j \rangle \right..$... |
Is it possible to combine Einstein's $E = m{c}^{2}$ and Max Planck's $E = hv$ and conclude mass is equivalent to frequency? If no, where exactly is the problem in concluding the same?
|
Physically, elastic materials are materials which return to their original state upon complete removal of applied mechanical loads under isothermal conditions.
In the book "Mechanics of Laminated Composite Plates and Shells 2nd Edition" by JN Reddy", the author defines
Materials for which the constitutive behavior is... |
I had some confusion about the idea of cutting the path integral to define states in quantum field theory. There are two versions which I have seen:
We do the path integral with an unspecified 'final' b.c. This would define a state at the cut.
We do the path integral with both b.c specified and then integrate over t... |
In the old theory of the strong force, where the strong force was thought to be conveyed by massive mesons (pions), as one can read here:
The discovery of the neutron in 1932 revealed that atomic nuclei were made of protons and neutrons, held together by an attractive force. By 1935 the nuclear force was conceived to ... |
I used Einstein's light box experiment in this. A description of the scenario, a box with a photon emitter is in space, out of reach from any gravitational field, I am floating in space watching the box as an inertial observer. The photon emitter emits a light beam, and the recoil causes the box to move in the opposite... |
If a tangential force is applied to a spinning disk, then the tangential velocity of a particle will also change. This means that angular speed should also increase. However, force is perpendicular to the angular velocity vector, so shouldn't angular speed value remain the same?
|
I have read this question:
Why did the universe not collapse to a black hole shortly after the big bang?
where Lubos Motl says:
This matter has no center - it is almost uniform throughout space - and has high enough velocity (away from itself) that the density eventually gets diluted.
Now this and none of the other (... |
Maxwell equations allows us to calculate the electromagnetic fields based on the motion of charged particles. On the other hand, to see how particles are affected by those fields, you add the Lorentz force, which is an approximation at low speeds, so it is modified relativistically.
The modification is $d\vec{p}/dt=q(... |
I was thinking... We could calculate the power of a runner by using the equation $P = fv$, supposing his velocity constant. But so raise me a question: What makes possible to run is the friction, so there is one force pointing acting on him in forward direction since he is pushing the floor back. Now, if he is at const... |
In cases of two- or three-dimensional space, why doesn't the Lorentz factor of a component of 3-space momentum depend on only the corresponding component of velocity? That is, why isn't there, for example, $$p_y=\frac{mv_y}{\sqrt{1-\frac{v_y^2}{c^2}}}?$$
I think I've studied only the introduction to SR, so ideally I ne... |
Suppose we have an electric field $\mathbf{E}$ given by
$$\mathbf{E}(r,t)=(\vec{E_1}e^{i \mathbf{k}_1 \cdot \mathbf{r}}+\vec{E_2}e^{i\mathbf{k}_2 \cdot \mathbf{r}})e^{i\omega t}$$
with $c|k_1|=c|k_2|=\omega$
Is this electric field unpolarized?
|
So I'm reading Sean Carroll's old blog post:
But to a modern physicist, this seems like a misguided quest. First,
because renormalization theory teaches us that $\alpha$ isn’t really a number at all; it’s a function. In particular, it’s a function of the total amount of momentum involved in the interaction you are con... |
$$\Delta H=\Delta (U+PV)$$
But in Ideal gas
$PV=mRT$ and $U$ is also a function of Temperature. So if throttling is an Isoenthalpic process and for an ideal gas, it's Isothermal then how do we explain the drop in Pressure?
|
I've been reading a technical report about inertial navigation.
The image is described as "conventional mechanical gyroscope".
It is then explained with "A conventional gyroscope consists of a spinning wheel mounted on two gimbals which allow it to rotate in all three axes".
I don't understand how this is supposed to ... |
The main sequence evolution of a solitary star depends most of all on its initial mass. Other factors influencing its evolution are the initial metallicity, rotation and magnetism.
Question: how does the initial sun-like metallicity affect the evolution while the star is on the main sequence,
(i) in a star of $1M_\odot... |
Let's consider a single charged elementary particle (i.e. NO internal structure, such as the electron) in its rest frame. Does it produce a magnetic field because of its spin? Would a neutral elementary particle with non-zero spin at rest produce any magnetic field? If yes, what expression should the magnetic field ha... |
I am having trouble solving this. The problem is the following:
Suppose a semisphere of radius $a$ (with its center of mass at $h = \frac{3}{8}a$) of mass $m$ located on a sliding surface. A massless, non-extensible string of length $b$ (b<a$) is attached to the edge of the semisphere. What's the tension of the rope i... |
I found the following result in a book:
but I do not understand what is the meaning of the magnitude of the curl of a vectorial field? and how is this related with the amount of spatial oscillations.
|
Am I correct in understanding that in string theory before the birth of the universe, fundamental strings did not interact with each other, and when the strings began to interact, space-time appeared?
|
Considering the Jordan-Brans-Dicke action:
$$S=\int d^4x\sqrt{-g}\left(\phi R+\frac\omega\phi(\partial\phi)^2+\mathfrak{L_{m}}(\psi)\right).$$
I was trying to get the metric field equations by varying the metric and got this:
$$ -\frac{1}{2}g_{\mu\nu}R+R_{\mu\nu}+\frac{\omega}{\phi^2}[-\frac{1}{2}g_{\mu\nu}(\partial\ph... |
I have been thinking recently about geothermal power and thermoelectric generators. Specifically, I am pondering a design involving a loop of two different metals, about two miles long, placed in a hole drilled into the earth. This would cause the Seebeck Effect between the junctions of the two metals.
Reading the See... |
I want to understand why there is freedom in choosing entries of an eigenvectors on some instances. I will take up a particular Hamiltonian to explain this.
$$H=H_0 \left[ {\begin{array}{ccc}
1 & 0 & 0 \\
0 & 0 & -i \\
0 & i & 0
\end{array} } \right]$$
This Hamiltonian has $H_0,H_0,-H_0$ as its eigenvalues... |
It has occurred to me I don't know if there is a general rule about this or not.
If I have an expression like:
$$\int \sqrt{g_{ij}\frac{dx^i}{dt}\frac{dx^j}{dt}} dt$$
I take the summation inside the square root (i.e. before performing the square root).
But is this a general rule ? If I see $\sqrt{a_{ij}}$ am I always ... |
When we consider rotation matrix along $z$ axis and take the infinitesimal value the parameter (rotation angle), we get corresponding generator of the rotation.It has the form shown in the equation.
$$J_3=\begin{pmatrix}
0 &-i & 0 \\
i & 0 & 0 \\
0 & 0 & 0
\end{pmatrix}$$
Now we say by taking exponential I.e. $e^{iJ_{3... |
In string theory, do fundamental gravitational strings interact with each other constantly, or can they interact and then cease to interact?
|
According to General Relativity and its experimental tests, a clock far above Earth ticks faster than it does on the surface of Earth. Because near the surface of the Earth space-time curvature is deeper. But I don't get why.
|
In wiki and open stax it is said that Newton’s Third Law includes the fact that Newton's Third Law involves the concept of direction in its statement but in this answer it is said that the direction aspect is not given in the statement of third law and requires extra experimental ideas.
The particular reason I'm concer... |
Imagine a region in space that has a changing magnetic field through it. Two imaginary closed loops are "placed" in that region such that the two loops intersect with each other at different angles. This setup would mean that if you placed wires where the loops are, a current on different paths would flow in a differen... |
I would like to find a ressource where the binding energies of the outer electrons of larger atoms are listed.
I'm discussing Neodymium lasers and I think it would be nice to have a graphic with all the different energy levels that will be used during the lasing process.
I would ideally have a nice picture similar to t... |
I have looked at the questions on this stack exchange and did not find a single convincing answer. Please absolutely remember the mathematical definition of only 4 things as you read this. Probability density, probability current, and the transmission and reflection coefficients. In this case the potential energy will ... |
When pouring something on ice, like deicing salt or vinegar, to make it melt at a lower temperature, does the energy required to melt it change (in a significant way)?
Edit: I am only interested in the energy required for the phase change (i.e. melting), not the energy required to reach 0,1 °C (or something like that)... |
Imagine you have a point A and a point B. Does it takes the same amount of joules to travel from A to B no matter how you do it (if in neutral conditions e.g. no wind)? For example, walking, riding a bike, taking the plane (the plane needs gas), climbing a mountain and using a hang-glider (going up the mountain takes e... |
I am building a model rocket. I want it to end up in a specific position. If I am taking into account the acceleration, starting position, end position, mass, and wind speed, how do I find the angle I have to point the rocket at in order to make it end up in that specific position?
Edit: Let me try to put this into per... |
There is a paper (PhysRevB.95.014435) in which the dispersion relation for some Heisenberg model on the honeycomb lattice is derived from the Landau-Lifshitz equation:
\begin{align}
\frac{d S_i}{dt} = - S_i \times \mathcal H_{\rm eff}
\end{align}
Their attempt from Eq. 2 to Eq.4 is pretty simple and I'll try the same ... |
This is my first time learning Young tableau, and I am struggling with a specific rule.
I am reading it from this lecture note.
The rule I am confused about is the very last point at the end of page 2. I have pasted a screenshot of it here for easy reference. Could someone explain a bit more why the tableau shown in th... |
In field theory, I've seen a free theory described as
A field with the specific Lagrangian density ${\cal L}=|\partial\phi|^2+m^2\phi^2$
A field whose equation of motion yields a linear set of solutions
A field with non-interacting i.e. free normal modes
The first seems too specific, the second seems too general, and... |
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