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In most basic statistical physics/condensed matter discussion the density of states is used to convert a discrete sum to a continuous integral
$$\sum_{\alpha} \mapsto \int d\epsilon \ g(\epsilon).$$
For example, a common derivation of the density of states can be done by considering the volume of a sphere in $k$-space ... |
Some Background
I was reading up on some elementary Lagrangian mechanics from David Morin's Classical Mechanics while also going through Goldstein's Classical Mechanics for further clarification. There was one recurring theme: in none of the worked-out problems was it checked whether the following constraints were met:... |
I'm a high schooler doing a question as follows:
"An electron moves from point A where the potential is 100.0 V to point B where the potential is 200.0V.The electron started from rest. Calculate the speed of the electron as it passes the point B."
The solution is to equate the work done on electron to kinetic energy ga... |
I am uncertain whether chemical potentials stay constant during chemical equilibrium.
Consider a closed container divided into two parts 1 and 2 filled with ideal gas particles. The barrier between parts 1 and 2 allows particle exchange.
The Gibbs energy for parts 1 and 2 are
$$G_1=N_1\mu_1$$
$$G_2=N_2\mu_2$$
The total... |
I'm trying to solve this problem :
Given a distribution of volumetric charge density in space:
where $r$, is the distance from the beginning of the axes: $$\rho(r)=\left\{
\begin{array}{cc}
\frac{A}{r} & r<R \\
0 & r\geq R
\end{array}
\right.$$ In addition, there exists on the surface charge density $\sigma$
on the su... |
Piece of Information 1:
This text states that since correlation and entanglement are equivalent for pure states, one could use a quantum-correlation measure as a quantifier of entanglement. For quantum correlation, one could possibly(?) use the so called correlation-function defined as
$$K=E(O_A\otimes O_B)_{\psi}-E(O_... |
Let's assume we have a floating iceberg. A book says the following:
$$mg = V_{\mathrm{tot}}\rho_{\mathrm{ice}}g = V_{\mathrm{und}}\rho_{\mathrm{w}}g$$
where $V_{\mathrm{tot}}$ is the total volume, $P_\mathrm{ice}$ is the density of ice, $V_\mathrm{und}$ is the volume under water, and $P_\mathrm{W}$ is the density of th... |
I have following question:
A particle is displaced from rest and released at time t = 0. It
performs simple harmonic motion (SHM). Which graph shows the variation
with time of the kinetic energy Ek of the particle?
I am quit confused on why the D is the correct answer. I choose C which is wrong as I believe the velo... |
I've studied and understand the differential and integral forms of Maxwell's equations, and understand the basic math and logic behind phasor notation for circuit analysis. Still, I'm confused as to the significance of Maxwell's equations in phasor form. They seem only to be functions of frequency, which from scattered... |
Let's try to solve 1 dimensional Dirac equation for a $\rm H^-$ anion. If you solve the time independent Dirac equation and allow motion of electrons only in the $x$ axis you get:
$$-\chi\frac{d\Psi_{4}(x_{1},x_{2})}{dx_{1}}-\chi\frac{d\Psi_{3}(x_{1},x_{2})}{dx_{2}}+(V(x_{1},x_{2})+m_{e}c^{2}-E)(\Psi_{2}+\Psi_{1}) = 0.... |
Suppose that the state of a system can be represented as a superposition of finite position eigenstates $|\Psi \rangle = \sum_{i}c_{i}|x_{i}\rangle$, where each $|x_{i}\rangle$ corresponds to a unique subregion $X_{i}$ of a larger region $X$ so that $\cup X_{i} = X$.
Let A be the observable corresponding to the questio... |
If I have a chamber of Alpha particles and I bombard it with electrons(of let's say 2EV)
and the electrons collide with alpha particles to form He+ Ions(which get formed in an excited state). so when the electrons come back to the ground level, photons get emitted. so what would be their energy(of photons) , will it be... |
I'm an undergrad with no direct coursework dealing with solid state physics so please forgive misunderstandings.
Say you have a well of semiconducting material surrounded by an infinite potential barrier.
If there is no voltage applied, the valence band is full and the conduction band is empty. Solving the Schrödinger ... |
In the free field theory, we an decompose the field with creation and annihilation operators $a^{\dagger}_k$ and $a_k$. $a_k$ acts on some state $|0\rangle$ and outputs $0$. We call that state the vacuum state—a state with no particles. $a^{\dagger}_k$ in contrast acts on the vacuum stays and creates a particle. We c... |
Reference: the rotation speed of galaxies in a galaxy cluster:
Is the dark matter associated with each galaxy in a cluster, sufficient to explain the rotation speed of galaxies in the cluster, or extra additional dark matter in the cluster in the intergalactic space is required to explain the galaxy rotation speed in ... |
This question is part of the International Physics Tournament 2023. The entire problem statement reads : How accurately can you determine the number of matchsticks in a matchbox from the sound it makes when you shake it ? Can the same methods be applied to a box containing chewing gums ?
I, along with my friends have ... |
Imagine the Earth faced the imminent crisis from climate change as the planet warmed by 1.5C. As a last ditch attempt to buy more time, humanity finally decided to do whatever it takes to stop the ongoing crisis. In order to cool the planet temporarily, it was decided to block the most direct rays of the Sun for the sh... |
Before two black holes merge, their individual event horizons must be perfectly spherical due to the No Hair theorem. If they weren't they'd be betraying information about the inside. After merging, the now larger event horizon is also perfectly spherical. However, there is no way I can come up with that gets from befo... |
As a photon orbits close around a Kerr black hole in an elliptical orbit that reaches into its ergosphere, the frequency of the light ray should increase due to frame-dragging. Given that:
$$
v = f \lambda_0
$$
And the equation for the angular speed of an object in the ergosphere of a black hole is:
$$
\omega=\frac{2Mr... |
It is well-known that we can use Born first approximation to calculate the differential cross section. To be precise, firstly we modify the potential as Yukawa potential
$$V(r)=\dfrac{\alpha e^{-r/a}}{r}, $$
and plug it into the Born approximation formula
$$f(\theta,\phi)=-\dfrac{\mu}{2\pi\hbar^2}\int{\rm d}^3x_1V(\vec... |
I encountered a type of problem in optics where we have to shift an object in front of mirror or lens but there has been an element of confusion in it. When we shift something like 'd' distance away or closer to the mirror to some existing distance like 40 cm, and we use the mirror formula should we ideally include the... |
How is the electric field same at any point from the planar sheet with uniform charge density which is enclosed by a gaussian surface as shown below
Now I can understand the formula derivation by using equation of flux by
$$E \cdot 2A = \frac{q}{\epsilon_{0}}$$
and with $\sigma = \frac{q}{A}$ one arrives at
$$E=\frac{... |
I am reading a paper in which the following relations is used :
The momentum space volume element can be written as $$d^3p_1 d^3 p_2 =4 \pi p_1 E_1 dE_1 4 \pi p_2 E_2 dE_2 \frac{d (cos \theta)}{2}$$
where $p_1$ and $p_2$ are the three-momenta and $E_1$ , $E_2$ are the energies of the colliding particles in the cosmic c... |
$$\rm ^9Be (\alpha, n) {}^{12}C$$
What does this notation mean in a nuclear reaction?
|
I am a new learner in compressible aerodynamics. When studying the shock tube, I struggle to derive the relationship between $M_{s}$ and $M_{R}$ after the shock is reflected from the end wall. How does this formula form step by step?
$$ \frac{M_{R}}{M_{R}^{2} - 1} = \frac{M_{s}}{M_{s}^{2} - 1} \sqrt{1 + \frac{2 \left( ... |
I would like to mention that I am a mathematician and not a physicist, so I apologize in advance if my question seems obvious.
Considering any linear PDE, it is common to understand the behavior of the solution by taking the Fourier transform of the equation. For instance, one can think about a linear Schrödinger equat... |
So imagine we are doing kinetic gas theory with spheres. To model the collisions however, we consider the potential used over here.
We choose the regularized potential as
$$ V_{\varepsilon}~=~\frac{(x_1-x_2)^2}{\varepsilon}\theta(|x_1 - x_2| - d).$$
where $V_{\varepsilon}$ is a family potentials of ${\varepsilon}$ as ... |
Consider a static current density $j_z(x,y)$ flowing out of an infinite 2D plane with $\mu=1$.
$j_z(x,y)$ should be physical such as $0<j_z(x,y)<M$ and $\lim_{\sqrt{x^2+y^2} \rightarrow \infty}j_z(x,y) = 0$.
The total magnetic energy can thus be calculated.
There are cases of $j_z(x,y)$ where the energy is infinite, su... |
I was solving a question of electrostatics and it was Friction as a method of charging is used for whom ? I answered both insulator and conductor because friction causes production of heat which in turn causes loss of electrons from one body which are then gained by other body but answer was insulators only. Why is my ... |
This is a very silly question and I really don't know the answer to it but curious to know.
Everytime I see the pics of suset on beaches the sun appear to go all the way down to the surface of the sea (as shown in the picture) but when I see sunset in my region , the sun disappears well above the horizon.
Why does t... |
Statement of my problem is that :
A solid dielectric cylinder of dielectric constant $k$ is placed in a uniform electric
field $ E_0 \hat{z} $ perpendicular to its length. Obtain an expression for the potential inside
and outside the cylinder.
What bothering me is that there isn't $z$ symmetry in the question and I h... |
In second quantization, the time-independent Hamiltonian for free fermions is written as
$$\mathcal{H}_0=\sum_\sigma\int\mathrm d^3 \mathbf r\; \Psi^\dagger_\sigma(\mathbf r) \frac{\hat{P}^2}{2m } \Psi^\dagger(\mathbf r) $$
In the presence of an electromagnetic field given by $A_\mu=(\phi(\mathbf r),\mathbf A (\mathbf ... |
A Homogenously charged cylinder of length L with Radius R and charged Q is presented. I am asked to find the dipole moment, the charge density is not given and only this Q value is given. I know the value must be zero due to the symmetry of the problem and that p the dipole moment is a vector quantity as such then you ... |
About a year ago I read a paper stating that a Dense Plasma Focus (DPF) could operate at ambient air pressure. But I can't find the paper anymore and what I've found in online journals seems conflicting and sparse.
Can someone in plasma Physics explain:
Is this possible?
What are the obstacles to this?
Why are plasma f... |
During a discussion on thermodynamics of ideal and real gases. A colleague, who is actually my prof, recently, claimed that during compression, work done on a van der Waals gas is lower due to intermolecular attractions, that the gas molecules are attracting each other, overall being attracted towards the 'inward' dire... |
For an object with temperature $T_1$ in an environment with uniform temperature $T_2$, the formula for rate of heat transfer by radiation is
$$P=\sigma eA(T_2^4-T_1^4)$$
where A is referred to as the surface area of the object.
However, for instance, if I have a cube lying on the ground, will the bottom face of the cub... |
Consider the following equation :
$$\Lambda^{-1}\Lambda^T \Lambda=A$$
Here $\Lambda$ are my lorentz transformations such that $\Lambda^T \eta \Lambda=\eta$. $A$ is some matrix.
I know that in terms of components, $\Lambda \equiv \Lambda ^\mu \space_\nu$.
Similarly, $\Lambda^{-1} \equiv (\Lambda^{-1}) ^\mu \space_\nu = ... |
I want to prove that the potential of a localised charge distribution:
$$\phi=\iiint_V\frac{\rho(\vec r')d\tau '}{4\pi\epsilon_{0}|\vec r-\vec r'|}$$ is indeed a solution to Poission's equation:
$\nabla^2\phi=-\frac{\rho}{\epsilon_{0}}$
Caveat: Without using the Dirac delta function.
If I have to specify a reason, I st... |
The efficiency of any heat engine doing work $W = |Q_{in}| - |Q_{out}|$ is given by:
$N = |W|/|Q_{in}|$
The reasoning for this given in my textbook is along the lines of:
The purpose of any heat engine is to transform as much of the
extracted energy into work as possible. We measure its success in
doing so by its ther... |
I understand the basics of how to evaluate tensor products. For example:
$$\sigma_z \otimes I =
\begin{pmatrix}
1 & 0 & 0 & 0\\
0 & 1 & 0 & 0\\
0 & 0 & -1 & 0\\
0 & 0 & 0 & -1\\
\end{pmatrix}$$
where $\sigma_z$ is the pauli z matrix and $I$ is the 2x2 identity.
My question arises when applying this math to two qubits.... |
I was wondering how does one go about solving for the spin (1/2) eigenstates in an arbitrary direction?
Let me specify my question. I had seen previously (such as Spin operator in an arbitrary direction) how to calculate such a problem when we are given the unit vector in spherical coordinates: ̂=(sincos,sinsin,cos) (w... |
If I understand correctly, if I were to work on an InP (100) wafer substrate, that would mean that the circular plane facing me would be the (100) plane of the crystal lattice. Now, I'm interested in studying electro-optical effects of InP. Let us take the Pockels effect for example. Let $\eta=\epsilon^{-1}/\epsilon_0$... |
I recently did an experiment to investigate the emf induced in a coil by letting a magnet fall through a coil. The voltage was measured by a voltage sensor, and then plotted against time on a Capstone program. The area under the curve was calculated by the program to give the magnetic flux.
Experimental Setup:
a 2500-... |
Carbon bicycle frames have the unusual property that they are superior to aluminum frames in high-frequency absorption. A cyclist on a carbon-frame bike will feel tarmac chatter far less than on an aluminum-frame bike.
Yet carbon frames are also famously solid. A carbon-frame bike will remains solid underneath a cyclis... |
I am no physics major nor math major to this but merely an amateur cosmology enthusiast, so in my previous inquiries I wasn't able to find anything on the premise that if all black holes obviously have different masses (which we know they do, as all objects do), and we know that each black hole's gravitational pull exc... |
The conventional way of explaining Kohn-Luttinger (KL) superconductivity (superconducting instability of electrons even when the interaction between them is purely repulsive) is by Friedel oscillations. The explanation goes something like this in 3d (three spatial dimensions):
The screened repulsive potential of a char... |
If I place one solenoid inside of the other, both of them in the same direction and same amount of loops, will the inductance be doubled or will it be zero?
|
lets say I suck water of a tube then put that tube in a lower tank why does water keeps flowing even when there is a component of gravity up.
my guess is that by bernullis law I add up some speed in the lower part of the tube then there is lower pressure there.then the air will flow towars lower pressure.
|
I was working on an experiment using the Geiger counter to determine the range of beta particles through different materials. The range is to be determined experimentally and compared to the theoretical prediction. What I cant quite figure out is how do I account for the particles absorbed in air and the entrance of th... |
What is the longest detectable (by today's technology) EM wavelength? and is there a limit of the energy that those with longer wavelengths that we cannot detect can carry? can there be a galactic or "Intergalactic space" scale standing EM waves? e.g. a standing wave between the BHs at the centers of the Milky-way and ... |
I want to remove moisture from common polymers used for 3d printing (PLA, ABS, PETG, Nylon) by placing them in a sealed chamber with desiccant (silica gel or molecular sieves).
A small fridge would be perfect for that application as they are airtight and cheaply available.
I wonder what would be an effect of powering t... |
In the paper "Experimental Verification of the Greenhouse Effect", the authors (Hermann Harde, Michael Schnell (2022)) describe an experimental setup that they say demonstrates the atmospheric greenhouse effect.
(NOTE: Some commenters point out that downvotes may be due to flaws in the experiment that they say leads to... |
I have read this question Different signatures of the metric in Einstein field equations (and related posts) on the invariance of Einstein field equations under metric signature change.
However, there is still something not clear to me.
In Carroll's book (which uses (- + + + )), the first-order Ricci scalar is (eq. (7.... |
I am studying the black body curve currently and am confused about the unit for irradiance. Why is it watts per unit area per unit wavelength working out to be power per unit volume? More specifically why is wavelength included here?
|
I am currently reading a physics paper in which the authors have complexified an ordinary differential equation (ODE). They mention the following statement in the paper:
"These branch points reflect the fact that two linearly independent solutions of the wave equation will mix when they are transported around a non-tr... |
In the standard derivation of the adiabatic approximation (see Sakurai in Modern Quantum Mechanics, Wikipedia) a differential equation for the coefficients is reached as
$$
i\hbar \dot{c}_m(t) + i\hbar \sum_n c_n(t) \langle m(t)|\dot{n}(t)\rangle = c_m(t)E_m(t) \tag{1}
$$
Now in order to find the inner product $\langle... |
In competitive swimming, swimmers are allowed to swim first 15 meters completely submerged, and it seems that they can swim much faster that way than if they swim on the surface.
I've seen several explanations on the Internet, some mention surface tension near the water-air boundary, some mention more turbulence, some ... |
So, suppose I'm considering a Hamiltonian similar to the form
$$\hat{H} = e^{iGx}\frac{\partial^2}{\partial x^2}$$
Wolfram alpha gives me an (ugly) solution to this simple MWE Hamiltonian, but I wonder in general if
There exists a recipe to solve this type of system. Or, other theorems about the existence or character... |
I'm slightly confused as to the physical reasons for why in the metal and n-semiconductor contact shown below it is known that electrons will tend to flow from the semiconductor to the metal rather than vice-versa.
The explanation (as I understand it) for why electrons initially flow from semiconductor to metal before... |
So I have a solid disk:
m = 2.98 kg
r = 0.2 m
and an axis in the - and + z direction (in unit vector form, the k dimension)
And I have to find the Moment of Inertia of the disk if the axis is at point (0.5, 0), assuming the center of the disk is at the origin.
How would I go about solving this?
Thank you!
P.S. How woul... |
I am not in physics but rather in computer science. I am trying to understand MPM modelling.
Right now I am trying to understand what the Piola-Kirchoff stress tensor is/measures.
My current understanding is this. Given a body configuration $\Omega_0(X)$ at time 0 and some deformation of it $\Omega_t(X)$ induced b a ma... |
I have to compute the contravariant metric tensor with off-diagonal terms, such as $g_{0i}\neq 0$. I started with the condition $$g_{\mu\nu}g^{\nu\lambda}=\delta^\lambda_\mu$$
but I don't know how to proceed. I can write
$$
\left\{
\begin{array}{ll}
g_{00}g^{00}+g_{0i}g^{i0}=1\\
g_{i0}g^{0j}+g_{ik}g^{kj}=\delta^j_i\\
\... |
Okay, I know a momentum eigenstate is not realizable in practice since it's not normalizable. But say we ignore the normalizability constraint, and just apply the rest of the theory. My question is, if we start with a two-electron system in momentum eigenstate $<\vec p_1, \vec p_2>$ with no external field, then accor... |
The typical argument goes that light rotates because there's no reason that it wouldn't. More precisely,
magnetization defines an axis $\to$ the dielectric tensor could be different along that axis.
non isotropic dielectric tensor $\to$ light polarization rotates
(2) follows from Maxwells equation's, however I find... |
So, there is a projectile moving across at some initial velocity and sometime during its path it splits into two fragments with their respective angle from the horizontal.
I was told to apply the conservation of momentum to find the final velocities of the two fragments.
My problems are:
That I don't understand why sho... |
I was trying to calculate the velocity of the earth around the suns orbit using the conservation of mechanical energy hence:
$$\frac{GMm}{R} = \frac{mv^2}{2}$$
$$\sqrt{\frac{2GM}{R}} = v$$
why is the last equation wrong?
and what would be the correct way to find it?
update already find the correct way but I still dont ... |
Usually, when physicists talk about singularities in Einstein's theory of relativity, they say that these cannot exist and that they are only mathematical artifacts that indicate that is likey that another, more fundamental quantum gravity theory (like loop quantum gravity or string theory) will be able to explain what... |
According to this post,
$$\mu_i = g_i + RT \ln \frac{N_i}{N_1+N_2}$$
It shows that chemical potential indeed do vary with composition. I have trouble understanding how this equation is derived.
I started from Sakur-Tetrode equation and the definition for Gibbs energy $G=U+PV-TS$ and I got the following for the ideal ga... |
Assuming that there is some observer "O" at location 0, and there are two events A and B, with B occurring 1m farther from A. Both A and B are equipped with two synchronized clocks reading exactly the same time.
1 Would the two events be simultaneous from observer O's reference frame?
2 Are events simultaneous being in... |
So I know that complex potential is just $Ω=Φ+iΨ$
$Φ$ is the potential function which associates a scalar value to every point on the field. Lines where $Φ$ is constant are the equipotential lines. In the real world, the scalar values to each point are temperature values at every point in a map while the equipotential ... |
I learned from a lecture that $G^{<}=-f(\epsilon)(G^r-G^a)$ is a type of fluctuation-dissipation theorem. However as far as I know the fluctuation-dissipation theorem is stated as $S(\omega)=2\hbar(1+n(\omega))\chi''(\omega)$ where $S$ is a correlation function, $\chi''$ is the imaginary part of response function and $... |
As stated, aren't the two formula indicating the same things as current is essentially what is in a wire?
|
At LHC, some analyses search for resonant HH production, from an unknown particle labelled $X$. They typically make the limit on cross-section of resonant HH production as a function of the spin of the unknown particle $X$ : spin $0$ and spin $2$. They overlap the theoretical cross-section of the model with a given spi... |
Why does boat/airplane propellers are designed so differently then of a turbine/pump propellers? (blade spacing, pitch, blade shape and width, etc) although both just push fluids backwards
|
Say that there is some spherical object which is soft enough to deform and flatten out significantly under its own weight when placed on a hard surface (like depicted in the image below)
What would the force required be to roll this kind of object along a flat ideal surface at a certain speed be, and if there even is ... |
Interaction-free measurements are based on the idea that even if interaction is not happening the chance that it may happen may change the result of the experience. such as in the Elitzur–Vaidman bomb tester, the existence of the bomb can be measured even if there wasn't any interaction with the bomb.
And also I rea... |
In the paper Tachyon motion in a black hole gravitational field by V. M. Lipunov he writes:
(…) Circular orbits for tachyons begin at the distance of $ 3/2~r_g $, i.e., at the distance of the innermost unstable orbit of ordinary particles. Note that the innermost unstable circular orbit for a tachyon is located at the... |
A well known fact about antenna broadcast and reception is that the AC current in the antenna dictates the direction it will broadcast EM waves. So for instance a vertical antenna will not broadcast along the direction of the axis of the antenna. (Ie no waves or few waves will be emitted vertical and directly above the... |
Let us have the equation as;
$A_{{\mu}{\nu}}$$B_{\mu}$=$C_{{\mu}{\nu}}$ , $\mu$ and $\nu$ are free indices.
Is the above equation a valid tensor equation? If not then what correction should be made to make the above equation a valid tensor equation?
|
I am trying to understand the link between the wavefunction and probability density. I can understand the probability density $\rho$ would be some function of the wavefunction, but I am unable to understand why it would be specifically $\rho = \psi^{*}\psi=|\psi|^{2}$. Why not some other functional form, say $\rho=|\ps... |
Hi I studied the phase transition using the text book statistical physics of field, Kardar.
But I can't understand the process (1.28) to (1.30).
Does anyone can help me?
|
I have a question about applying the variational principle to obtain the geodesic equation for null geodesics. Specifically, I am unsure about the justification for the choice of the Lagrangian. I will briefly explain taught to derive the geodesic equation for timeline geodesics.
The metric for a given spacetime geomet... |
Which is the physical interpretation that in Dirac's equation the wavefunction is a spinor?
|
I'm trying to derive the BZ Lagrangian (density) from the Dirac Hamiltonian density and some questions popped up.
BZ Lagrangian is
$$\mathcal{L} = \frac{i}{2}(\dot{\bar{\psi}}\psi - \bar{\psi}\dot{\psi}) + p_\mu(\dot{x}^\mu - \bar{\psi}\gamma^\mu\psi)\tag{1}$$
where the four-potential $A_\mu$ is set to zero for simplic... |
I am studying photoelectric effect and it is known that if the irradiated light on metal surface has a lower frequency than that of work function the electrons do not eacape, no matter how intense the light is. However, I imagined a thought experiment where work function is W=hυ and light consisting of photon with a fr... |
Are elementary particles distorted when hit by gravitational waves?
If they are, how much can they be distorted near a black hole merger? Can that distortion somehow break the particle? In that case, what are the emitted particles?
|
I saw this video on YouTube about using rotating liquid metal as parabolic mirrors to make reflecting telescopes.
In the video apart from the standard equation of the curve the liquid makes, the focal length of the mirror so formed was given as
$$f=\frac{g}{2\omega^2}
\\g=acceleration \, due\,to \,gravity\\\omega=angul... |
When you grow a sandwich-structured semiconductor, like the one on the image below, you create a quantum well due to different materials having different bandgaps and band offsets. The energy difference between confinement levels of electrons and holes (green lines) is measured with photoluminescence setup.
The photol... |
While I was watching some videos about rocket and its engines, I saw that the principle behind it is Newton's Third Law, because while the gas is exhausted from the rocket it has a reaction force putting the rocket up.
So the reaction force produced by the gas exhaust could be written as this:
$$ F_{rocket} = F_{gas} $... |
According to the formula, intensity $I = \frac{\left( dN dt \right) \left( h c \right)}{\lambda A}$, with $\lambda$ being the wavelength and $A$ the area. When wavelength increase, KE decrease, assuming constant intensity, so why when a photon has lesser KE, the number of incident photons per unit time $\frac{dN}{dt}$ ... |
Please kindly advise why the parameters $\gamma$ and $\beta$ are both zero for classical Newtonian mechanics (see attached screenshot of Wikipedia (the page about Binet's equation)) instead of $\gamma = -1$, $\beta = 0$ such that it complies with the ordinary $F = - \frac{G M m}{r^{2}}$ equation. Is it coming from any ... |
I am trying to find a rigorous proof that the Kruskal-Szekeres extension is maximal. The Kruskal-Szekeres extension of the well-known Schwarzschild solution is given by the Lorentzian manifold $(M_{KS}, g_{KS})$ where $M_{KS} := \{ (T,X) \in \mathbb{R}^2 | T^2 - X^2 < 1 \} \times S^2$, with $S^2$ being the unit two-sph... |
Can someone explain to me, how Steel tensile strength works?
Lets take "S355" for an example.
S355 means, its tensile strength is 355 N/mm2. Which means when i place 355N worth of load to an 1mm2 area, it will deform/go to state which steel doent withstand the force anymore also even break.
So basically this is maximum... |
In a well-lit room, a light source shines light on the objects in the room, some of which reflects back off the objects. We can make the light source brighter by causing it to emit more photons, which means more photons are hitting the objects and also reflecting off the objects and thus they appear brighter as well.
T... |
Hello fellow physics enthusiasts! I recently came across with a generalization of Lami's theorem for four coplanar, concurrent and non-collinear forces in static equilibrium. I was wondering if anyone could suggest some potential applications or real-world scenarios where Theorem 1 could be useful? Additionally, I'm cu... |
I am currently reading Reif's Fundamentals of Statistical and Thermal Physics and I am unfortunately rather baffled at the end of Chapter 2 which Reif wraps up with a discussion of quasi-static processes. At the bottom of page 75, a quasi-static process with respect to some system $A$ is defined as (I paraphrase)
a pr... |
What would hypothetically happen if, for example, exactly 1 Cl- were added to the entire universe? I study chemistry and it is always the case that we keep the charges on the left and right in reactions and have to balance them accordingly. I used to wonder what would happen to ions that change into the gaseous state i... |
In PRL 104, 087401 (2010) (PDF), the authors provide an alternative way to formulate dispersive photonic media.
Here I would like to take lossless dielectrics with Lorentz dispersion $\epsilon\left(\omega\right)=1+\frac{\omega_p^2}{-\omega^2+\omega_0^2}$ as an example. I also let $\epsilon_0=\mu_0=1$ for simplicity and... |
I've read about the overall average distance between stars in the milky way, and I've read that one of the best explanations for spirals arms is that they are density waves - that is, they are indeed denser than the spaces between them.
Do any estimates exist for how much denser stars are distributed in arms, or how mu... |
If I am given:
the distance of two points
the (constant) force being enacted on the object moving between those two points
how can I figure out:
the time it would take the object to reach the other point under the forces influence on its position, with zero relative velocity at the destination (essentially that the ... |
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