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I am reading about the solutions to the wave equation through a separation of variables (time and position): $H(x,t)= A(x)B(t)$.
But since the solutions we are seeking are solutions with constant frequency then the temporal part takes the form $B(t)=e^{-i\omega t}$.
My doubt is why the temporal part must have this expo... |
Where can I find a formula to calculate the magnetic force two cylindrical/disk magnets exert on each other that have their axes aligned (there is no lateral displacement). I found formulas in papers (https://www.sciencedirect.com/science/article/abs/pii/S030488530900746X?via%3Dihub) and on wikipedia (https://en.wikipe... |
Can anyone explain me the meaning of this line?
"Velocity of matter wave depends on velocity of particle generating it"
|
You know how antennas work and create EM waves...They oscillate charges which create EM waves
Well I'm not satisfied with that explanation so it would be great if you could use maxwells equation to explain why this happens-
Why accelerating charges release electromagnetic waves?
why electric and magnetic field detach... |
I'm having trouble coming to any meaningful answers in this question,
It seems to me like all of the variables given can be put generally in terms of T. I can't seem to figure out any kind of equation of state that seems to give a meaningful answer. Can anyone get anything out of this question? Cheers.
|
What would happen to capacitance and other quantities like Voltage if I initially take a Parallel Plate capacitor with each plate having equal charge "$q$" and then connect it to a constant voltage supply (battery)?
I know Capacitance is a geometrical quantity and the battery doesn't supply any net charge to capacitor ... |
I am studying robotics and I am studying how to send acceleration inputs to control a unicycle robot.
I have seen that I can send the unicycle linear and angular accelerations since they are the derivatives of linear and angular velocity.
But now, I would like to send different types of accelerations, such as inertial ... |
As we know, water becomes ice at $0^°$C.
After becoming ice, if we lower the temperature further ($<0^°$C), then does the density of ice increase further?
If yes, in that case, does the volume decrease?
|
There's interesting statement about amplitude of Goldstone bosons:
I wanna to understand simple argument for statement of vanishing of amplitudes in the single scalar soft limit. In principle, it is obvious that this have direct relation to symmetry of model. But technically I can't find argument for this.
So, how to ... |
Looking at the QED-Lagrangian
$$\mathcal L = -\bar\psi(\not\!p + e\not\!\!A + m)\psi -\frac14 F_{\mu\nu} F^{\mu\nu} $$
I was wondering: While $\bar\psi\not\!\!A\psi$ describes the interaction between the electron field (or rather generally, a charged fermion) and the photon field (a neutral boson), the $\bar\psi\not\!p... |
Why a non-reversible weight lifting machine cannot lift higher that a reversible one is related to my current post, but everyone in that thread seems to have understood how Feynman's simple machine works visually. I haven't.
Figure 4.1:
And the excerpt from the Feynman Lectures on Physics Chapter 4.2:
A very simple w... |
Spring Force = $F_s$
Charge Force = $F$
If the system is balanced
Based on Newton's Law
On the horizontal line
Is it
$2F_s = F$
Or $F_s = F$ ?
|
if it took a very certain amount of energy to excite an atom, how come when it de-excites it emits a photon of lower energy?
I know that's what scintillators do, I Just want to know the microscopic process behind it.
|
There seem to be several different ways in which mass manifests itself, in particular with reference to fundamental particles:
Gravitational mass.
Inertial mass.
The coupling to the Higgs field.
The energy and lifetime of virtual particles.
Values for the mass of the fundamental particles are shown on the table in th... |
I am talking about bluetooth headphones which have magnetic ear buds. We know same poles repel and opposite poles attract each other.
My question is:
Why bluetooth ear buds which have magnet inside them always attract but never repel?
|
I came across a question in my Textbook which I am unsure about.
Two polarising filters are aligned to transmit vertically polarised light. They are held in front of a source of horizontally polarised light. The filter closest to the light source is rotated by 45 degrees. The intensity of the light passing through the... |
Why commercial airplanes use long, slender wings? Isn't it to maximize lift, we make the plane's wings as wide as possible?
|
Recently I read about the Poiseuille's equation which relates the flow rate of a viscous fluid to coefficient of viscosity ($\nu$), pressure per unit length($\frac{P}{l}$) and radius of the tube ($r$) in which the fluid is flowing. The equation is
$$\frac{V}{t}=\frac{πPr^4}{8\nu l},$$
where $V$ denotes volume of the fl... |
note: This may be a homework question but I am not asking anyone to give me the answers as I already have them: Im only looking for an explanation for what's actually going on.
Question: once the capacitors are charged, the switch is moved to position Y. State what happens to the p.d across Capacitor P and Q
TO some e... |
Recently saw some interesting optical effects inside/under the ice on the frozen pool which I never noticed before. Looks pretty much like thin-film interference patterns to me. A quick search did not yield any relevant results, so I'm looking for an explanation for these optical patterns.
|
I had a doubt regarding this after going through a problem.
A thin plate $A$ of mass $m$ is affixed on the upper end of a spring, lower end of which is affixed to the ground. In equilibrium, the spring is compressed by an amount $x$. Another thin plate $B$ of mass $2m$ dropped from a height $3x$ above plate $A$ hits pl... |
I have 2 different expressions for the relativistic energy of a body and I'm trying to link them both:
The first one is given by
$$E=\sqrt{(mc^2)^2+(pc)^2},$$
with $m$ the mass and $p$ the momentum.
The second one is given by the mass energy $mc^2$ together with the kinetic energy $T$:
$$E = mc^2 + T.$$
I also have tha... |
On exercise 4.6 from Klepper's Book "Intro do mechanics" there is a plane on a landing lane. It has its engine off but is braking with force $F_b$. Also, it is attachted to a sandbag that does friction $f_s$. It asks how far the plane goes.
I found a solution for this exercise that says that momentum is conserved. But ... |
Suppose we would like to anti-symmetrize a tensor
$$T^{\mu_1, \mu_2,\ldots, \mu_n} = G^{[\mu_1, \mu_2,\ldots, \mu_r]} H^{[\mu_{r+1},\ldots, \mu_n]},$$
where $G$ and $H$ are anti-symmetric. One could do this iteratively by applying the anti-symmetrizer
$$\Lambda_{1,2,\cdots, n} = \frac{1}{n}\left(1-\sum_{i=1}^{n-1} P_{i... |
Background: I am an electronics (device level) student who suddenly wished to understand semiconductor stuff from basics (at solid state level, without any background in that).
What I understood: From this video, F. Bloch said that in a crystal there is some periodicity of arrangement of atoms, hence a periodicity in p... |
I've seen this data set in a few places.
Found here: https://lco.global/spacebook/light/redshift/
Do the measurements from SH0ES and Planck that cause the Hubble tension alter this table?
I can find the H_0 from each of this studies, and I can assume the Planck measurement applies to a range of > 13 billion years, but... |
in one of our Particle Physics exercises, we're supposed to calculate the pseudorapidity of a particle produced at a hadron collider with a three-momentum $\vec p = \left( p_x, p_y, p_z\right) = \left( 30, 40, 50\right)$ GeV. As a hint, we're given that
$\theta$ can be obtained by $\frac{p_T}{p_z}$
which confuses me.... |
For a universe with a constant expansion rate, i.e. the Hubble constant $H_0$ is a constant, the Hubble law is
$$v=H_0d$$
where $v$ is relative velocity between two galaxies and $d$ is the separation between them.
I read that the age of the universe is given by $$\frac{d}{v}={1\over H_0}$$
which is the Hubble time $t_... |
In my student book they separate these two and indicate that sparks need high voltage to occur while arcs need low voltage with normal or low pressure and electric arcs CAN come with heat and bright light. But when I search on the web many people said that arc is just a hotter version of spark. So what is the differenc... |
I am not a physicist. I have only rudimentary notions about the following.
I looked for similar questions on SE but I did not find any. I also tried search engines but results relate to angular velocity which has nothing to do with my question.
As far as I know, the energy of a particle at rest $E = mc^2$. When the par... |
I need to know why we can't use the $ \int\vec{E}.d\vec{S}$ as the electrical flux. But we try to define electrical flux density vector $ \vec{D}=\epsilon_{0}\vec{E}$ and then try to use $ \int\vec{D}.d\vec{S}$.
In Sadiku Elements of electromagnetic he has just mentioned
The flux due to the electric field E can be ca... |
If I were asked to give an example of an axiomatic mathematical theory, I'd be able to answer: set theory, probability theory, maybe group theory (assuming the elements of the definition of a group can be considered as axioms).
But it seems more difficult to give an example of an axiomatic physical theory.
I'm not nece... |
I have been struggling in the past weeks to understand how should I setup a laser interferometer for my experiment. I am not a physicist, and I am quite new to optics.
I have a Cassegrain telescope with a primary mirror M1 and a secondary mirror M2 and I want to monitor the relative displacements and tilts between M1 a... |
I have a follow-up question to my own question: In there, I wrote that at a hadron collider, $$\theta = \frac{p_T}{p_z}.$$ Why does this Eq. actually hold, i.e. how can we derive it? From this thread, I found this nice picture:
Do we then say that $\tan\left( \theta \right) \approx \theta$ for small angles $\theta$?
|
I find it best to start this question with a thought experiment. We have a rocket ship and Earth. For our purposes, Earth has no acceleration or velocity and begins at the origin. The rocket ship accelerates away from Earth with a constant acceleration $a$. This rocket ship begins at the origin ($x'_0=0$) with 0 veloci... |
Suppose that we have a quantum particle with defined momentum $p=\hbar k$, this means that the particle is in an eigenstates of the momentum operator $|k \rangle$. We can now ask: what is the wavefunction $\langle x | k \rangle =\psi _k(x)$ of this particle? It turns out that this is:
$$\psi _k(x)=\frac{1}{\sqrt{2\pi}}... |
I seem to be having a doubt with the potential energy of a simple pendulum. If potential energery is defined as $-\int F(x)dx $ and the net force on the pendulum is $-mg\sin(\theta)$, then wouldn't the potential energy be $-mg\cos(\theta)$? But shouldn't it be $-mgl\cos(\theta)$?
|
Using the usual notation for rectangular (Cartesian), cylindrical, and spherical coordinates, which of the following expressions represent a plane wave propagating in free space?
$$e^{-jk_0R\sin(\theta)} $$
$$e^{-jk_0R\cos(\theta)} $$
$$e^{-jk_0R}$$
$$ e^{-jk_0r}$$
where $j$ is the imaginary unit, and $k_0$ is the wav... |
I'm an undergraduate who visited a course on differential manifolds and now I have the task to reformulate the maxwell equations in terms of differential forms. The most obvious question that arises first is: On what manifold are the forms defined?
Unfortunately, it seems to be difficult to get good answers. Some peopl... |
Can anyone provide me with a complete mathematical proof about why an observer frame cannot surpass the vacuum speed of light?
I have looked for answers in Quora and FB groups but no one is really convincing. In fact the majority assume that the constancy of vacuum speed of light in all referentials without any proof,... |
I solved a question in electricity using the Gauss law, but comparing with others revealed the possibility that my answer is incorrect.
We have a Sphere with radius $R$ and Charge density $\rho$. The center of the sphere is located in the origin. Now inside of that sphere, there's a smaller sphere, with 0 density (no c... |
I'm trying to model the propagation of a dipole source and I need to know what is the directivity function (i.e. the polar pattern function) which describes it. I've read in an article that a dipole can be described with this formula:
where the last exponential represent the Green's function right? So what is here th... |
Vast areas of desert sand are being shone on upon by the sun. Now that's some ENERGY!
Using this proposed apparatus:
Sunlight over large area is concentrated on steam chamber, where water turns into vapor.
The high temperatures of the gases in the steam chamber will push on the loose piston, compressing the air above ... |
While studying the 3+1 Formalism of General Relativity, the slices of constant $t$ confuse me on what the physical essence is.
For example (and I've made another question related to that, after that started studing 3+1 GR book) in simulations where a Black Hole - Neutron Star merger is happening, the $t$ parametere is ... |
I recently watched PBS spacetime's video series on the black hole information paradox. Where they first discussed the no hair conjecture and then later also the true destruction of information by Hawking radiation.
This led me to wonder, if information is apparentely unavailable to the outside universe after it has ent... |
So I learned recently that star systems are relatively flat due to the conservation of angular momentum.
On how large a scale does this degree of flattening apply. i.e will the universe eventually flatten out, or galaxy clusters, or is it just star systems. At a guess, it depends on the validity of this statement:
Give... |
I have a quick question:
I want to calculate how much more likely we expect the process $\pi^{+} \rightarrow e^{+}\nu_{e}$ to be in comparison to $\pi^{+} \rightarrow \mu^{+}\nu_{\mu}$.
I know that in nature, the process $\pi^{+} \rightarrow \mu^{+}\nu_{\mu}$ occurs almost exclusively.
For this, I tried to use Fermi's ... |
I'm stuck on the problem given in Exercise 10.3.5 on R.Shankar's Quantum Mechanics book. The chapter name is "Systems with N degrees of freedom".
Consider the exchange operator whose action on the $\Omega $ basis is
$$P_{12}|\omega_1,\omega_2\rangle=|\omega_2,\omega_1\rangle$$
i.e. exchange the labels.
I'm trying to pr... |
This is a stupid yet interesting question. The best way I discovered till now is wrap it up in a sweater, and put it under bed. However that way I couldn’t access the snooze button later. I tried blocking the sound opening but, nothing happened. Any ideas?
|
Is there any rigorous way to show that it is impossible to have any inertial reference frame with the speed of light apart from the blow up of the Lorentz factor?
|
Situation
I've taken a course on QFT, covering canonical quantization (of the scalar, EM and Spinor fields), Feynman diagrams and rules, etc. --- it was your basic one-semester introduction to QFT.
I've also had an introduction to the Path integral formulation and was shown how to do basic calculations in it, but I did... |
Here's a question that has been nagging at me:
Suppose I've got a sum of two stationary states from the particle in the box:
$\Psi(x,t)=c_1\psi_1(x)e^{-iE_1t/\hbar}+c_2\psi_2(x)e^{-iE_2t/\hbar}$
The probability density is $\Psi^*(x,t)\Psi(x,t)$
Which works out to $\lvert{c_1}\rvert\psi_1^*(x)\psi_1(x)+\lvert{c_2}\rvert... |
If I have two masses connected together, it's pretty simple to calculate the CoG of the system.
But if the two masses are connected with a hinge?
My question arrives from the motorcycle world. I'm a dirt biker and, when I'm cornering, I don't touch the seat but I have to put all my body weight on the footpeg. I always ... |
I wonder if the problem in the image can be solved with the Wigner-Eckart (W-E) theorem. These elements have to vanish.
I tried introducing the identity operator in between $r$ and $p$ to then use the W-E theorem for the new matrix elements. I was hoping that the selection rules for each of the Clebsch-Gordan coefficie... |
In the collision between the red disk (mass $m_1$) and the green disk (mass $m_2$) as shown bellow, why the force that mass 1 makes on mass 2, $\mathbf{F}_{12}$, is along the line connecting the point of contact and the center of the ball (green arrow)?
Is this always true? Is there a simple explanation for this?
|
I was reading that the relation
$dt=\frac{dz}{H(z)(1+z)} $
between time and redshift (H is the Hubble constant) holds.
I don't understand this. I thought the relation between time and redshift is
$z=H(t-t_0)\Rightarrow dz=H dt$
What am I doing wrong?
|
so we all know that the Faraday Cage prevents most EM radiation from entering the Faraday Cage. But what about, if we place radiation within the Faraday Cage - can it escape outside? I sort of recall working in class on a lab and finding that yes, it does escape - because the charges go to the outer surface - but I am ... |
The following infinitesimal transformation of phase space coordinates (for infinitesimal $\epsilon$) is apparently canonical (preserving Hamilton's equations and Poisson brackets):
$$ q_i' = q_i + \epsilon \frac{\partial g}{\partial p_i} $$
$$ p_i' = p_i - \epsilon \frac{\partial g}{\partial q_i} $$
where $g$ is the ge... |
I'm trying to understand the electric displacement field $\mathbf{D}$ for a lossy material with conductivity $\sigma$ and permittivity $\epsilon$.
Most textbooks I've looked at only consider perfect dielectrics when discussing $\mathbf{D}$.
However, the first two sentences of the Wikipedia article on $\mathbf{D}$ state... |
Consider the following Lagrangian (density)
$$
\mathcal{L} = (\mu/2) (\partial_t q)^2 - (Y/2) (\partial_x q)^2 -\alpha(\partial_x{}^2 q)^2
$$
$\mu, Y, \alpha, q$ are respectively mass/unit length, Young modulus, coupling, and position coordinate. Context: first foray into field theory via Goldstein chapter 13
In an ef... |
In the first paragraph of chapter 2 in this paper, the authors say that an effective volume is reduced to an effective area, when the thin target approximation is valid.
What is the thin target approximation, and why this approximation is valid when the interaction length of the particle is much longer than the thickne... |
In solid states physics, there is an approximation that goes as follows:
$$k_0|\vec{r}-\vec{R}|\approx k_0 \left(r-\frac{\vec{r}}{r} \cdot \vec{R}\right)$$
where $r$ is the norm of $\vec{r}$ and it is assumed that $r\gg R$.
I tried to start the derivation by writing out terms in $x,y,z$ but it became a mess and I was n... |
The Aharonov-Bohm effect is often presented via a region in space where the magnetic field $\textbf B=0$, but the vector potential $\textbf A \neq 0$. Usually, this is motivated via an infinitely long solenoid, which is said to have a vanishing magnetic field outside the coil.
However, if the solenoid becomes infinitel... |
I have a capacitor (C) connected to a battery of emf 100V. Hence potential drop across my capacitor is 100V. Now I introduce a dielectric between the plates of capacitor which increases the capacitance to C'. My book says that placing a dielectric inside the capacitor reduces the potential difference between the plates... |
Question 2. For nonrelativistic free particle $E=\frac{p^{2}}{2m}$ and using the de Broglie relations the corresponding dispersive relation becomes $$\omega(k)=\frac{\hbar k^{2}}{2m}$$
Then following the relativistic free particle energy relation $E=\sqrt{p^{2}c^{2}+m^{2}c^{4}}$ and then using the de Broglie relations ... |
My book defines Electrode Potential for a Galvanic Cell as follows:
A potential difference that develops between the electrode and the electrolyte is called Electrode Potential
$$E= V_{electrode} - V_{electrolyte}\tag1$$
It further defines cell potential as:
The potential difference between the two electrodes of a g... |
I know this will sound dumb for the people who are here but I need to learn eventually
when can I use $pv=RT$ and when to use $pV=nRT$
|
I've read that the cause of
Nuclear fission and nuclear fusion lies in the fact that Nuclear Binding Energy confers stability to a nucleus. This is why too heavy or too light nuclei resort to these processes to attain stability, and become nuclei with intermediate atomic weight. Two questions come to my mind here
is i... |
Lets say I have ice of mass $m_i$ and initial temperature $T_i$ and specific heat $s_i$ . And I have water of mass $m_w$ and initial temperature $T_w$ and specific heat $s_w$ . I have put both this water and ice in a copper container with mass $m_{cu}$ , specific heat $s_{cu}$ and initial temperature $T_w$ . What will ... |
A body is moving with a constant speed on a circular path. What happens to its Kinetic energy?
Kinetic energy is dependent on velocity but Kinetic energy on the whole is a scalar so direction does not matter. I am in doubt as to the answer of this question.
Any help would be appreciated.
|
The de Broglie relations connecting the wave-particle dual nature as generalised from photons to all matter particles are given by $$E=\hbar\omega$$ and $$p=\hbar k$$ (Characterizing a single plane wave with wave parameters $\omega$ and $k$ .)
Are these relations true for a time dependent potential $V(x,t)$ And if yes... |
My text book says "electrons of the same spin in degenerate orbitals tend to exchange their positions and this leads to stability". Firstly, why should the electrons exchange their positions? I read somewhere that the electrons would want to exchange their positions in order to get a greater area of movement and conseq... |
The gif below is the exact experiment I did.
I blew some air into the left arm and when the liquid in the right arm reached the maximum, the right arm was closed.
Keeping the right closed, I closed the left end too and then opened the right end.
When the left end was open, it was under atmospheric pressure which is ... |
I am looking for a precise definition of complementary principle. It is rather briefly mentioned in the textbook, and I feel that authors have deliberately avoided defining it precisely. I'm a math major, perhaps I didn't get the point. The most understandable description so far I found in wikipedia:
"The complementar... |
I would like to prove that Noether charge $Q$ is a generator of the same symmetry as the one that due to the Noether's theorem led to the current $j^\mu$ and charge $Q$ in classical field theory (I have found a lot of proves in case of classical mechanics), i.e. I would like to prove
$$\delta_\epsilon\phi = \{\phi, Q_\... |
I have a combined microwave oven/grill (Ikea Granslos) that broke down recently. It looks like this:
There is a wire shelf in the middle that I've always assumed to be compatible with both baking and microwave modes. However recently the microwave's magnetron stopped working and I had the oven serviced. The technician... |
I'd like to know the kinetic energy stored in a moving door (pushed open) of unknown mass.
If the hinges were frictionless, I'd use a weight attached to a string and a pulley to determine the energy by measuring the resulting increase in potential energy of the weight (i.e. measure the height when the door is stopped).... |
Take a one-dimensional plane wave $\exp(i(kx-\omega t))$. How can I show that its phase is a $Lorentz \ Invariant$? How to derive the form of $4-wavevector$?
|
$$\Gamma^{\mu}_{\mu v} = \frac{\partial_{v}(|g|)^{0.5}}{(|g|)^{0.5}}$$
I am trying to show this equality, but I'm only getting through:
$ \Gamma^{\mu}_{\mu v} = 0.5*[g^{\mu\mu}(\partial_{v} g_{\mu \mu}) + g^{\mu v}(\partial_{\mu} g_{vv})] $
I would appreciate any tip to go on
|
I believe it's named $\omega_1$ (correct me if I'm wrong) equal to $\gamma B_1/2$. The fact that it's equal to $\gamma B_1/2$ allows me to see how it works mathematically after a quick calculation, but what actually is the physical meaning of the Rabi Frequency $\omega_1$ for an RF field applied to an NMR setup? And ho... |
I read the following statement:
There is matter and energy in the universe, and their mutual gravitational attraction will slow down the expansion of the universe, leading to a monotonically decreasing expansion rate $H(t)$ (the Hubble constant) -- a decelerating universe.
Why does gravitational attraction slow down ... |
In this picture it is clear that there is a larger no. Of clouds near the sun as compared to a distance farther. Moreover the clouds seem to form vortex rings around sun.
why is there more density near the clouds , is it just an optical illusion. If yes then what's the reason if no then why ?.
I'm not sure if thi... |
you know amperes circuital law? Well in that equation there's a dot product between the magnetic field B and a length element dl...why is that? I mean its not like the magnetic field can be at an angle to the length element. Its always parallel to the length element so $\cos(0)=1 $ which means the dot term is not neede... |
According to thermodynamics every adiabatic system and (with no external energy added) will reach thermodynamic equilibrium or an ergodic state (2 law of thermodynamics entropy can not decrease in a closed system). State at which Temperature (or mean kinetic energy of the particles) will be same everywhere. So the answ... |
For example, neutrinos have an extremely small mass and are expected to be in relativistic motion. Why is that so?
|
If I calculate the temperature of the Sun by replacing the effective frequency of the Sun (598 THz) in Planck's curve for Blackbody radiation, the result will be 10170 K. Still, in Wien's displacement law, the result will be 5778 K, is there an answer for this problem?
|
How could light from a TV screen refract when viewed through a helmet's transparent visor?
|
I am looking for a concrete example of a transparent matter and wave length of a radiation at which the refractive index of the matter is less than 1 (if they exist, of course).
There are several similar questions around, e.g. Medium with refractive index less than unity? however I have not found an answer to my questi... |
I am interested in the following question: What are all objects that are invariant under Lorentz transformations? And, once a list is provided, how to justify that these are indeed ALL such objects?
Here is a paper in which it is shown that "up to multiplication by a scalar, the Minkowski metric tensor is the only seco... |
Q:If we know that the acceleration vectors of all points of the rigid body are equal to each other at all points of time, can we conclude that the body is undergoing pure translational motion?
I recently learnt that both the necessary and sufficient condition for a Rigid body to be in pure translational motion is that,... |
Given a plane wave with the electric field component $$ \tilde{E}_{in} = E_0(-\hat{x} \cos \theta + \hat{z}\sin \theta)\exp [ i \frac{\omega}{c}(x \sin \theta + z \cos \theta) - i \omega t]$$
I've calculated the reflection on a metallic plane and it yielded
$$ \tilde{E}_{ref} = E_0(\hat{x} \cos \theta + \hat{z}\sin \th... |
I did the Foucault pendulum experiment today. I used a 45 pound weight hung on about 12 or 15 feet of inelastic cord. I understand that a great and highly precise experiment will show one full rotation of the plane of oscillation in about 24 hours, but my pendulum was rotating at a rate that appears to be too fast.
... |
The low-energy effective description of a given QFT is an expansion of the form
$$
\mathcal L_\mathrm{IR}\sim\sum_{n,m} \lambda_{n,m}\phi^n\partial^ m\phi
$$
where we include all terms that are compatible with the symmetries of the original UV theory.
The usual narrative is that $\mathcal L_\mathrm{IR}$ captures all th... |
Can we use the work-energy theorem for a liquid in a container which is accelerated and where the liquid is static with respect to the container to find the pressure at different points? I tried but I didn't get the correct answer, can someone please tell me how we can use the work-energy theorem here?
|
A negative pion breaks down into a muon and a muon antineutrino.
What do the traces of the pion decay look like in a bubble chamber with a vertical, static homogeneous magnetic field?
My ideas:
The B-field deflects the pion on a circular path.
But my question is: How does the radius change after the pion has decayed?
B... |
Is there a good reason why we can use uniform circular motion to get the equations for a mass on a spring, without invoking calculus?
This relationship is often used to find the equations for the spring in non-calculus physics, because obviously there is no way for those students to solve the differential equations, bu... |
In my book , some sites and even on this question, I read that the change in entropy of a system in a reversible process is directly proportional to the heat added and inversely proportional to the temperature at which the heat is added.
And thus
$$∆S =\frac{KQ_{rev}}{T}$$
But I want to know why don't we have a proport... |
In Ta Pei Cheng's GR book, the comoving coordinate system is defined as
$$t=\text{the proper time of each fluid element}$$
$$x^i=\text{the spatial coordinates carried by each fluid element}$$
The comoving observer flows with a fluid element. The comoving coordinate time can be synchronized over the whole system.
I have... |
The problem:
The standard derivation of the Rayleigh-Jeans law, in a cubic reflective cavity with a small blackbody in it, would have you believe that the cavity has an energy density of $kT$ for every frequency that creates a perfect standing wave.
This doesn't make any sense since this would mean that the blackbody i... |
Assume we have 2 sets of non-interacting fermions which I show by $\psi^{\pm}$ and $\chi^{\pm}$ where we have $\left< \psi^{+}(z) \psi^{-}(0) \right>=\frac{1}{z}$ and similar for $\chi$. Now we bosonise the fermions by setting $\psi^{\pm}=e^{\pm i X}$ and $\chi^{\pm}=e^{\pm i Y}$ where $X$ and $Y$ are free bosons. I ca... |
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