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I noticed that all the problems about elastic collision have "strict mass conservation" that is, if two masses $m_1$ and $m_2$ collides and make $m_3$, $m_4$, atleast one of them is gonna equal $m_1$ and the other is gonna equal $m_2$.
Curious, I tried to prove that the objects' mass between the collision has to be con... |
I've been reading Horatiu Nastase's notes on AdS/CFT, but I was confused about a certain relationship he claimed. If we compactify supergravity on $AdS_5\times S^5$, we may expand the fields in Kaluza-Klein modes
$$\phi(x,y)=\sum_n\sum_{I_n}\phi^{I_n}_{(n)}(x)Y^{I_n}_{(n)}(y),$$
for $x\in AdS_5$, $y\in S^5$. $I_n$ is a... |
For example, What prevents my feet from sinking and blending into the ground? Or my 2 hands from blending and morphing into one when I clap them? Is it merely the density of objects? Space between atoms?
|
Is it something like "implosive compression"? Cannot find the correct term.
Explosive decompression is when the pressure rapidly drops, e.g. spaceship gets a hole and passengers cannot breathe; I'm looking for a coined term for when the pressure rapidly rises, e.g. deep sea submarine gets a hole underneath and the air ... |
I have seen similiar Questions being asked for example Why Does Change of Magnetic Flux Induce an emf?
However i am not satisfied with the answers.
It seems to me that this Question is usually answered with the equations or the pure Maths that this is a Vector identity.
However what is the visual view of this? in other... |
Does the presence of a neodymium magnet around (or in the proximity) of the iron (no connection and At a distance of 1 millimeter ) lead to the gradual weakening of magnet effect?
What if it connects?
|
Two point masses m1 and m2, separated initially by distance d, move towards each other under mutual gravitational force.
Find the time they take to collide?
The main problem I'm having is to solve the differential equation...
|
The Rashba-type SOC is usually caused by structure inversion asymmetry(SIA). I can understand that the Rashba-type SOC splits surface states because interfaces including surfaces have SIA. But I am not sure that Rashba-type SOC splits bulk bands if there is lack of inversion symmetry in the bulk. Although I know Dress... |
By the Young Tableaux construction, a triplet of $SU(2)$ (diagramatically, two boxes side by side) is supposed to be a two indices symmetric tensor.
However, one of the most known and minimal extensions of the standard model is that of adding a complex colorless scalar triplet in the $(\mathbf{1},\mathbf{3},1)$ represe... |
For example, if i have a horizontal orifice plate in a tube and i'm pushing flow through it, there will be significant turbulent mixing downstream of the orifice plate. E.g. https://www.youtube.com/watch?v=KbTnJwaVUcQ&feature=youtu.be
This turbulent mixing will reduce the static pressure of the flow i believe, resultin... |
I'm studying Friedman and Susskind's Special Relativity and Classical Field Theory.
In Lecture 6, they derive
$$m{dU_\mu\over d\tau}=eF_{\mu\nu}U^\nu,\tag{6.33}$$
but only when $\mu=1, 2, 3$. ($F_{\mu\nu}$ stands for $\partial_\mu A_\nu-\partial_\nu A_\mu$.) To prove that this equation also holds for $\mu=0$, they give... |
We have a small bob attached to an elastic rubber wire and we are given values of the wire’s Young’s modulus, length, and area. My doubt is not to know the answer specifically, just to review my process.
My thought is we have to find the time period of small oscillation of bob only up to it goes downward and comes bac... |
[edit]: I reformulated my question to first talk about general spectrum analyzer and then ask about how vision works (which is a particular case of spectrum analyzer as I explain below).
Let's assume we have a sensor that needs to analyze a spectrum of a signal $f(t)$. In theory, to find the Fourier spectrum of a signa... |
Experimentally, we determine the value of the coupling constant by measuring the scattering cross-section and compare it with the results calculated by the scattering amplitude.
However, in the expression of the scattering cross-section, it is proportional to the square of scattering amplitude, which means it is propor... |
I understand the principle of conservation of energy and momentum in classical physics. I am aware of the fact that such conservation laws arise due to fairly deep mathematical symmetries in the natural laws, such as time-invariance.
Some theoretical physicists propose that time might actually be comprised of discrete ... |
Does stable mean that an isotope has a very long half life, for example xenon-124 has a half life of 1.8 x 10^22 years, or does it mean that fissure is theoretically not possible, or does it mean that the isotope has a very long half life, but the exact number is unknown?
|
I was studying the derivation of the relation between pressure ($P$) and root mean square speed ($v_{\text {RMS}}$) of an ideal gas from Fundamentals of Physics by Halliday, Resnick, Walker. (The same derivation can be found in Wikipedia page on kinetic theory of gases under "Equilibrium properties" section.)
One of th... |
Currently I'm learning how to calculate the edge effect of a material. I try to calculate edge state of a Haldane model in a zigzag graphene. Since Im writing in a second quantisation basis, each element in my hamiltonian kernel representing total hopping contribution on different site.
Considering the simplest cases: ... |
Trying to grasp this quote from Schroeder's textbook
Why are the entropy, pressure, and chemical potential "all the thermal properties?" What about $T$, $U$, $V$? This may have something to do with so-called "natural variables." Not sure.
Thoughts?
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Given a metric tensor $g_{\mu\nu}$ it is possible to calculate the geodesic equations from:
$$\dfrac{d^2x^{\mu}}{ds^2}=\Gamma^\mu_{\nu \eta}\dfrac{dx^\nu}{ds}\dfrac{dx^\eta}{ds}$$
where the $\Gamma^\mu_{\nu \eta}$ are the Christoffel symobols. How is it possible to know if there are runaway solutions in the geodesic eq... |
An answer at Chemistry.SE tells the following anecdote:
Another fill gas to avoid is sulfur hexafluoride. A tennis ball manufacturer once decided to fill tennis balls with sulfur hexafluoride, assuming this would prevent the balls from going flat as a consequence of the high molar mass of sulfur hexafluoride. But the ... |
Let $\theta$ be a fermionic quantity and $f(\theta)=f(0)+\theta\frac{\partial f}{\partial\theta}=f(0)+\frac{\partial_r f}{\partial\theta}\theta$. Under a variation $\theta\mapsto\theta+\delta\theta$ we have
$$f(\theta)\mapsto f(\theta)+\delta\theta\frac{\partial f}{\partial\theta},$$
using the first formula, or
$$f(\th... |
$SO(3)$ group is defined as linear transformations that preserve euclidean norm. Now if I identify $\phi$ (angle in $xy$ plane whose axis of rotation is $z$-axis) $0$ to $2\pi\beta$ where $\beta$ can vary from $0$ to $1$. What happens to our spherical symmetry? Will $SO(3)$ group still preserve the euclidean norm?
Acco... |
I am trying to find the frequency of the oscillations of a plunger of mass $m$ and area $A$ within a closed equilibrium at both ends. If in the equilibrium state it divides the cylinder into two equal volumes $V_1$. The gas pressure is $p_1$ and the processes are considered adiabatic.
Could you give me an idea?
|
I hope this (and not MathOverflow) is the right place to post this question. I am a math student taking a methods of mathematical physics course, in which we cover the solution theory the non-linear Schrödinger equation $$i u_t+ \frac{\Delta}{2}u=\lambda|u|^{p-1}u.$$ I understand that this PDE (or some special case of ... |
I know as a general fact that higher frequency sound dampens quicker in air so when music is heard from a distance only the bass part is audible.But I don't know what the physical reasoning behind this is. I couldn't find an answer anywhere on the internet (or they were too technical for me to understand). I would appr... |
Say I have a Lagrangian density with kinetic term $\mathcal{L}_{kin} = \phi \Box \phi$.
To derive the equations of motion, I could integrate by parts to obtain $\mathcal{L}_{kin}' = - (\partial_{\mu}\phi)(\partial_{\mu}\phi)$, then apply the Euler-Lagrange equations to obtain $2\Box\phi=0$. (Correct me if any of this i... |
I looked online for a really long time already for crystals which thermal neutrons can pass throw without significant change in their energy. Does anyone here know which crystals have the minimum energy attenuation coefficient for thermal neutrons? (Please contain references)
|
I believe particle accelerators move atoms at 99.999% the speed of light. If the accelerator was oriented perpendicular to the sun, a particle moving at this speed would experience sizable length contraction in the direction of the sun. I calculated the normal gravitational acceleration of the sun at the radius of ear... |
Do the numerous experiments that demonstrate a violation of Bell’s inequality also provide any data that the “communication” (I’m using that word for simplicity) between the entangled particles is superluminal but not simultaneous OR that such “communication” is indeed simultaneous?
I’ve looked at the papers of several... |
I've always thought that velocity is the quantity $\vec v=\frac {d \vec x} {dt}$ by definition. That is, velocity is a quantity whose measurement is the above operation of the quantities $\vec x$ and $t$.
Then I studied quantum mechanics and I've seen the indetermination principle:it is impossible to know position and ... |
I suspect these particles exist, but are extremely short-lived, even compared to other unstable, exotic particles...
|
I've recently started reading the book Biocentrism, by Robert Lanza and Bob Berman, which in its mind-blowing chapters, discusses the perceptions of reality, space, and time. Lanza states that:
If one could travel at lightspeed, one would find oneself everywhere in the universe at once. This indeed is what a photon of... |
I've been trying to better understand matrix product states (in order to implement them in code in the near future), so I'm considering small examples. I was wondering if I could get some clarification on how to express states as an MPS for this specific case.
In the 2 site Ising model, we have a Hamiltonian in the fo... |
Imagine two flat conducting plates (3 x 3), one as the anode and the other as the cathode, submerged into electrolytes (e.g. sea water) and a DC current is applied to this apparatus. Could current flow through this configuration now? Would the current spread out along the electric field line between the plates? And how... |
After years of solving this problem over and over again as a tutor, this is the first time I came across this question. Solving this could be useful if a future student asks this.
Let's say there's a block on an inclined plane of mass $m$, we have the following two coordinate system in which we can represent the forces... |
A finite chemical potential contributes to the Lagrangian $\mathscr{L}$ of a QFT by coupling to the associated conserved charge $\mathscr{Q}$,
\begin{align}
\mathscr{L} \rightarrow \mathscr{L} -\mu \mathscr{Q}
\end{align}
Consider the chemical potential associated to particle number, and say a scalar field $\phi$, at ... |
I am learning about a model of the human spine I saw and was doing a thought experiment with a ruler to try to understand the physics.
Suppose I have a plastic ruler that's not rigid but also not super easy to bend. Let it be totally straight. Now suppose I fix the bottom of the ruler and twist the top. The top twists ... |
For a generic $c \ge 1$ 2D CFT, I (wrongly?) expect to be able to write its torus partition function as
$$Z(\tau, \bar\tau) = \chi_0(\tau) \bar \chi_0(\bar \tau) + \sum_{(h,\bar h) \ne (0,0)}n_{h,\bar h} \chi_h(\tau) \bar \chi_{\bar h}(\bar \tau)$$ with $$\chi_0(\tau) = \frac{1-q}{\eta(\tau)}q^{-\frac{c-1}{24}} \qquad ... |
I was watching the show Snowpiercer on Netflix and it’s basically about about the last of humanity in a train that is constantly moving on tracks around the frozen earth. The earth temperature average is $-133^\circ\ C$. They say if the train stops moving (comes to a full stop) they will freeze to death within $13$ min... |
I am working on Lorentz transformations and I get a tensor of the form
$$M_{abcd}=\epsilon_{ab\mu\nu}\Lambda^\mu\hspace{0.1cm}_c\Lambda^\nu\hspace{0.1cm}_d$$
Where $\epsilon_{abμν}$ is the totally antisymmetric (pseudo-)tensor of Levi-Civita.
Is it posible to interchange contracted indices so that I can get
$$M_{abdc}=... |
In special relativity we can define the proper distance between two events as the length of a rod that connects the two events in the rest frame of the rod. However, this seems to require the ability to define a global inertial frame unlike the proper time which can be measured by free-falling between two events.
In ot... |
I feel like this is a silly question but I am having trouble wrapping my head around it. Lets use Andromeda as an example, since it has its own observable universe (slightly shifted from ours but with the same radius) does that mean that it would have that sliver of space and energy/mass within it acting on it but not ... |
[Edit] Not sure why this was closed. The answers there do not answer my question, and are not even correct...
Imagine a charge sitting in space. It causes an electric field everywhere, with magnitude $\propto r_{old}^{-2}$
But now let's say we move the charge a little. This will change the electric field everywhere ... |
In some sense, describing the strong force using an $SU(3)$ Yang-Mills theory makes perfect sense: Yang-Mills theories describe massless bosons, of which the gluon is clearly a member, while the two most common hadrons were observed (in deep inelastic scattering) to consist of three components, motivating an $SU(3)$ sy... |
Suppose that we have "spins" $\sigma_1,\dots,\sigma_N$, with $\sigma_i\in\{1,\dots,q\}$, for $i=1,\dots,N$, and that our Hamiltonian is
$$
H = -\frac{J}{N} \sum_\stackrel{i,j=1}{i\ne j}^N \delta(\sigma_i,\sigma_j) - h \sum_{i=1}^N \delta(\sigma_i,1),
$$
in which $\delta$ is a Kronecker delta: $\delta(\sigma_i,\sigma_... |
I apologize for asking a question similar to this before, where in particular I asked for a derivation of Fr = Iα from the presuppositions of F = MA and the conservation of angular momentum. However, all the derivations just presupposed that a sum of mini-torques equals the actual torque, the actual torque being the “r... |
The book says:
"The string should be perfectly flexible, if we like to neglect the effects of different velocities of the different parts of the string during the oscillation."
Can anyone explain what actually is going on over here? I mean how does the different velocities of different parts of the string affect the ... |
A transverse sinusoidal wave on a string moves from left to right. A snapshot of the wave is shown. Consider the red point on the figure being pointed to by the red arrow. Which way is this red dot moving at this instant?
I thought it's moving up. But the answer is moving down. I don't quite understand. Could anyone ex... |
Let $\phi$ be a real-valued scalar field in $N$-dimensional spacetime with coordinates $(t,\vec x)$, and consder the equation of motion
$$
(\partial_t^2-\nabla^2)\phi(t,\vec x)+V'\big(\phi(t,\vec x)\big)=0
\tag{1}
$$
where $\nabla$ is the gradient with respect to the spatial coordinates $\vec x$, and where $V'$ is the... |
I am trying to understand why the hypothesis of configuration interaction methods is valid, i.e. I want to understand why one would think that an $N$-body wave function would be in the span of antisymmetric functions that are simultaneous eigenvectors of each operator that commutes with the hamiltonian (this is the fun... |
Gravitational waves, like the electromagnetic waves, are also transverse. By transversality of the EM waves, we mean that ${\vec E}\cdot\vec{k}={\vec B}\cdot\vec{k}=0$ i.e., the accompanying electric and the magnetic field (which are two $3$-vectors) vibrate in a plane perpendicular to the direction of propagation spec... |
The derivation:
Let, there is $m$ mole of gas, $p$ amount of pressure, $v$ amount of volume, $T$ amount of temperature, and $U$ amount of internal energy. Now, $dQ$ amount of heat is supplied to this gas so that its internal energy changes by $dU$ and external work done by the gas be $dW$. Also, if the volume of the c... |
In an ideal battery, the battery forces are equal in magnitude to the electric forces (the ones that are present when battery is not connected externally) and thus we conclude that E.M.F. ($\varepsilon$) of an ideal battery equals the potential difference between its terminals when terminals are not connected external... |
For a long solenoid, when the formula describes solenoid length, is it referring to the length of the wire wrapped around the magnetic core or the length of the core?
|
I am currently studying the textbook Infrared and Raman Spectroscopy: Principles and Spectral Interpretation, second edition, by Peter J. Larkin. Section 9. Selecting the Raman Excitation Wavelength, says the following:
Fluorescence involves excitation of a fluorophore within an absorption band, followed by nonradiati... |
When defining the Wigner characteristic function of a state represented by the density matrix $\rho$, I have seen various sources [including https://arxiv.org/abs/1110.3234] first define the Weyl operator
$$D_\xi = \exp(i\mathbf{x}^T\Omega\xi)$$
and then use this operator to present the characteristic function as
$$\ch... |
Imagine a situation where a long masless stick is inserted through a ring, and fix one of the ends of the stick. Then, the system is given an impulsive force such that it starts rotating with an initial velocity $\omega_0$, the ring will start moving outwards, and thus, the system will experience a negative torque. I w... |
I’m working on a research project wherein we are trying to solve a problem very similar to VLBI delay. We have two radio receivers, and we know their locations. We also know at what time one receiver detected a signal, and the coordinates of it’s beam-pointing center. We want to determine at what time the second receiv... |
I am facing a conceptual difficulty while reading about black-hole(BH) horizons. Consider for simplicity a Schwarzchild(SW) BH, with a null hypersurface $\zeta$ denoting its horizon at $r=2M$ and let $g_{\alpha\beta}$ denote the metric. Finally suppose $K^{\alpha}$ is a Killing vector for this space. Then, we know that... |
The eigenstate of the annihilation operator $a$ is given by the state $a\mid \alpha \rangle = \alpha \mid \alpha \rangle$. In the Fock state basis, we can expand this state as
$$\mid \alpha \rangle = e^{-\frac{1}{2}\vert \alpha\vert^2}\sum_{n=0}^\infty \frac{\alpha^n}{\sqrt{n!}}\mid n \rangle$$
I am bit confused about ... |
How do we know that the human eye is most sensitive to a light of wavelength of $555$ $nm$ and power of $1/683$ watt? How are experiments performed for obtaining this result? What's so special about the number $683$?
|
I am currently looking into the Stefan-Boltzmann Law, and I am constantly seeing different quantities used. In some books I see "Intensity" and in others I see "Radiance", "Energy desnity" or "Radiancy". Could anyone help me understand why different terms are used and what they mean? Thank you.
|
I read this article which is on how Feynman thought of the difference between physics and mathematics.
Feynman's point is that physics is to understand nature while mathematics is to make their own world. But I'm quite confused with the word 'understanding'.
This answer points out that physics is not to identify the tr... |
I was looking for an intuitive explanation as to why the Doppler effect happens. I haven't found any, but this is what I thought:
-Waves emitted travel at a constant speed
-The source emits a wave
-If the source remained still, then in a given time, there would a large distance between the emitted wavefront and the sta... |
In the second minimum (the 3rd step) there is a smaller decrease in light intensity. For this to happen, wouldn't you need to be looking at the plane of orbit from above rather than directly along the plane of orbit? Because if a person was looking directly along the plane, then it would just be a full eclipse of the ... |
I am currently studying the textbook Principles of Optics: Electromagnetic Theory of Propagation, Interference and Diffraction of Light, 7th edition, by Max Born and Emil Wolf. Page 5, chapter 1.1.3 Boundary conditions at a surface of discontinuity, says the following as a note at the bottom of the page:
$^*$ For late... |
We know unlike charges attract and like charges repel.
The magnitude of this force of attraction or repulsion decreases as the distance between the charges increase.
As a result the force exerted due to the potential difference on the electrons decreases as it moves away from the negative terminal in any circuit. Thus ... |
I am currently studying the textbook Principles of Optics: Electromagnetic Theory of Propagation, Interference and Diffraction of Light, 7th edition, by Max Born and Emil Wolf. Page 5, chapter 1.1.3 Boundary conditions at a surface of discontinuity, says the following:
Instead of the volume charge density $\rho$ the c... |
Since 2019, the meter, kilogram, ampere, and kelvin, are defined by setting exact numerical values for the speed of light $c$, the Planck constant $h$, the elementary charge $e$, and the Boltzmann constant $k_B$.
The second still remains as being defined to be the duration of 9,192,631,770 periods of the caesium-133 at... |
Just wondering, why is it that blue light will refract less than red light, i.e. why does the fact that blue light has a shorter wavelength mean that it will refract less at a boundary?
I read somewhere that the wavelength decreases of light as it enters an optically denser material, which seems logical given that freq... |
If we apply $F=ma$, there is no net force and as such there is no acceleration in the center of mass. But due to the friction acting, there is a torque which gives rise to an angular acceleration of the object ($τ=Iα$) and as a result you can find a tangential acceleration on the object. How come the same object has t... |
Suppose that we are in the Weak Field Condition, that is:
$$g_{\mu\nu}=\eta _{\mu\nu}+h_{\mu\nu}$$
where $\eta _{\mu\nu}$ is the metric tensor of flat space time (Minkowski spacetime) and $h_{\mu\nu}$ is a perturbation such that:
$$|h_{\mu\nu}|<<1$$
Perfect. But now I would like to find the tensor $g^{\mu\nu}$; by defi... |
Given that a wave-function $\psi$ can be written as the superposition of plane waves where $\mathbf k$ is the wave vector (3D) and $g({\mathbf k})$ is a complex fn, must be sufficiently regular to allow differentiation inside the integral.
Now, the author states that,
any square-integrable function can be written in t... |
Suppose that we are dealing with the following matrix:
$$A=\begin{bmatrix}a_{00} & a_{01} \\ a_{10} & a_{11}\end{bmatrix}$$
but I don't want to use matrix notation, insted I want to use tensor notation, so I write this matrix as:
$$A^{\mu}_{\nu}$$
Question is: $A^0_1$ is equal to $a_{01}$ or $a_{10}$? And from which co... |
Assume a Chern-Simons theory on a 3-mfld of the form $\Sigma_g \times S^1$, where $\Sigma_g$ is a Riemann surface of genus $g$. In his paper, Witten shows that one can use the Verlinde formula to get the dimension of the Hilbert space associated to $\Sigma_g$, which equals the partition function of the theory. Furtherm... |
We all know we have 4 fundamental forces, and among them we can combine 3 forces but not gravity as in Standard model and some other. But force is something we can measure, as Einstein told us in general relativity so gravity in reality doesn't count as force, so why we tried to combine it with other forces because in ... |
Consider, for example, the third excited state of an infinite square well:
Now consider the following potential:
If we wanted to sketch the rough shape of the third excited eigenfunction of this potential, we shouldn't have to go through the full set of calculations, but we should be able to deduce what it will look ... |
I am working on black hole quasi normal mode, in particular I am working on the time domain tecnique for the calculation of QNM. I am studying this paper by Carsten Gundlach, Richard Price, Jorge Pullin, the one that introduced the time domain tecnique for the study of black hole perturbations.
I have been strugglin on... |
We know if a object has escape velocity (EV) it reaches space (ignore atmosphere friction), but at what angle. if an object travels parallel to earth surface with EV, will it escape curvature and reach space. If it travel horizontal and after reaching EV, it make slighlty an angle, will it reach space
Thank ... |
For an irreversible sudden expansion from $V$ to $2V$, no heat is added during the expansion. However, the entropy changes by $N\log2$. I'm not sure how there can be a change in entropy without any heat added, since $dS = \frac{dQ}{T} = 0$. Of course, integration can yield $\Delta S = C$, where $C$ is a constant, but I... |
Considering the incident optical wave $E_i=e^{ikx}$ and reflect optical wave $E_r=e^{-ikx+i\pi}$,where $\pi$ corresponding the half wave loss.The superposition of incident wave and reflect wave is $E=i2sin(kx)$.but generally we only conside the real part of E as the real existence of optical. it seems no optics existen... |
Since the earth moves around the sun in an elliptical orbit and the sun is located at one of the foci, hence the distance between the earth and the sun continuously changes, so why doesn't the force of gravitation change throughout the year as the masses of the bodies obviously remain the same?
|
If we look at crystallisation as a tiling problem, i.e. filling the space with a given set of tiles of arbitrary shape. Then the time that it takes to solve this problem has to be bounded below by the computational complexity of the tiling problem (of this kind) itself. Infact, maybe we can atribute amorphous ice forma... |
Why is the EMF of a battery always more than the voltage when current flows through the battery? Most answers say that because there is internal resistance in the battery there is a voltage drop, but isn't it true that when electrons are moved from low potential to higher potential within the battery they gain energy b... |
I would like to estimate the magnitude of a radio signal received from a transmitter by first principles:
Transmitter antenna length $L=1$ m
Transmitter antenna cross-sectional area $A=1\hbox{ cm}^2$
Number of electrons per unit volume in antenna $n_e=10^{28}$
Radiation resistance of antenna $R_R=10\ \Omega$
Power radi... |
I think I have found a way to easily understand time-like and space-like paths with the contect of a little linear algebra. My question is: is my understanding, below, correct?
When I learned General Relativity, one source of some confusion was how to find the actual time or distance from a metric. In particular, suita... |
What is the energy required to hold a mass in place? To lift 1kg 1m at sea level I must use 9.8 J. but if I simply grab onto a 1 kg mass that is on a table and the table is removed. I am now using energy to hold it in place. But since the mass is not moving there is no work and therefore supposedly no energy, but obv... |
!
When I see pictures like this and when my teacher explained to me how electrons flow inside a wire I imagined electrons to be moving inside the conductor where there are the atoms or jumping on the inner surface of it not in the empty space in the wire
But the thing is I then learned that the more the diameter of the... |
For architectural purposes, this question is vital.
If I were to construct an insulated cylinder $10\ m$ in height and $1\ m$ in radius and fill it with some fluid, and leave it for some hours, would the top of the cylinder be a higher temperature than the bottom?
I know pockets of hot air rise, but does their temperat... |
This question might be stupid, but when I compute $\bar{B}$ in the Lagrangian, I have to multiply 3x3 $B$ matrix with 4x4 $\gamma_0$ matrix (Dirac's conjugation) which are incompatible in size. What is wrong here? Is it because of the Trace being taken? (Sp = spur = trace)
|
Suppose that I am going to host a big party one month from now, and I have various liters of cold beverages that will need to be refrigerated by the time of the party. I have a fridge at home (which is on and being used under a normal everyday home fridge usage pattern); however, there is enough free space in it for th... |
Problem
In performing non-dimensionalization, I often get confused about the functional form of the dependence of one quantity on other variables. As a basic example, imagine a physical variable $\phi(x)$; one can obtain the dimensionless form by dividing this by a constant $\phi_0$, i.e. $\phi^*(x) = \phi(x)/\phi_0$.... |
I have read some texts that axiomatize special relativity in first-order logic, but I haven't yet found any for general relativity. Can someone direct me to such a text?
|
I've been reading Flip Taneda's 'quantum diaries' articles, and he references the famous fact that the W boson (weak force) only interacts with left-handed electrons and right-handed positron.
BUT... Does the antimatter-W interact with the right-handed electron and left-handed positron?
|
Some physical systems are analyzed using QM or QFT, whereas others are analyzed using classical physics.
Question: How can one refine this qualitative distinction to yield some kind of quantitative measure of the "degree of quantumness" or conversely the "degree of classicality" of a physical system?
Notes:
Part of th... |
A canonical equation of motion has form:
\begin{equation}
\dot{p}_i = -\frac{\partial H}{\partial q_i} = \left\{ p,H\right\}, \quad \dot{q}_i = \frac{\partial H}{\partial p_i} = \left\{q,H\right\}.\tag{1}
\end{equation}
For a classical particle in external potential field the view of Hamiltonian $H(q,p) = \frac{p^2... |
To what I understand, the following is a valid way to introduce the angular momentum $\mathbf L$ in the Lagrangian system of a rigid body. We can consider the extended configuration space to be $M\times \mathbb{R}=SO(3)\times \mathbb R$. For a left invariant Riemannian metric $g$ in $SO(3)$ we can define the Lagrangian... |
Is at point S current entering is not equal to current leaving? I am confused over this concept. Like we have net current zero when we consider a point outside toroid, shown in first diagram - current entering equals current leaving. So why don't currents cancel when we consider a point between radii a and b- of radiu... |
I am trying to understand why Taylor says in his Classical Mechanics text, "we can always subtract a constant from the potential without effecting any physics."
I assume "doesn't effect any physics" means the equations of motion are unaltered — as is the result of adding a total time derivative to a Lagrangian.
How are... |
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