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What would be the displacement-time graph for a body dropped from a certain height which bounces back to the same height after hitting a surface? [closed]

For a freely falling object, displacement-time graph looks like this: When we observe the motion of a ball thrown upwards, the graph looks like this: When the ball moves upwards retardation occurs ...
Kakiaririki's user avatar
2 votes
0 answers
37 views

When is the Lagrangian a Lorentz scalar?

The Lagrangian $\mathcal{L}$ can be defined as the Legendre transform (when it exists) of the Hamiltonian $\mathcal{H}$, a non-Lorentz scalar quantity (as $\mathcal{H} =T^{00}$). My questions are, ...
Gabriel Ybarra Marcaida's user avatar
1 vote
0 answers
12 views

Connection between dispersion relation and symmetries of the Hamiltonian

I am having trouble understanding intuitively the connection between the dispersion relation and the symmetries of the Hamiltonian. For example, suppose we have a lattice and there are four sub-...
JosephSanders's user avatar
0 votes
0 answers
14 views

Magnetic Field - 2 types

i have just started studying magnetism in electrostatics, electric field exists. Is there a magnetic counterpart for this, if so then what is it, what is its unit and how do we define it ? Is this ...
Anton Bert's user avatar
1 vote
0 answers
20 views

Does electric and magnetic field from electromagnetic radiation are 2D based?

I'm getting into physics, specially in electromagnetism. When we're talking about electromagnetic radiation. Does it has a 2D shape when it's propagating through space? Does Maxwell's equations ...
Psi's user avatar
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-1 votes
1 answer
29 views

Magnetic Field Generation in a Vacuum Through Special Relativity

The way special relativity explains electromagnetism is that when electrons move, their lengths contract due to relativistic effects, even though they do not move at extremely high speeds. This ...
Gopal Kaushik's user avatar
0 votes
0 answers
18 views

Calculating Binding Energy of Th 230 nucleus

Ok this is NOT a homework question. But it’s somewhat related. Please bear with me. In calculating BE of Th 230, I used the rest mass of proton as 1.007276u and rest mass of neutron as 1.008665u (as ...
esdoublelef's user avatar
2 votes
3 answers
61 views

Wikipedia states that the relativistic Doppler effect is the same whether it is the source or the receiver that is stationary. Can this be true?

According to Wikipedia, the relativistic Doppler effect is simply the classical Doppler effect for a stationary source, $1-v/c$, times the relativistic time dilation, $1/\sqrt{1-v^2/c^2}$ (where v is ...
John Hobson's user avatar
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0 answers
27 views

Passive transformation confusion [closed]

I'm reading Group Theory by A. Zee, specifically, chapter I.3 on rotations. He used the passive transformation in analyzing a point $P$ in space. Two observers, one labeled by unprimed coordinates ...
mathemania's user avatar
0 votes
0 answers
25 views

Question regarding friction acting on a disk on a conveyor belt [closed]

I have the following problem on which i am working A horizontal conveyor belt is running at a constant speed of $v_b = 3.0\hspace{1mm}m/s$. A small disc enter the belt moving horizontally with a ...
Hhh Hhh's user avatar
2 votes
1 answer
50 views

Time evolution of state in first and second quantization

I was trying to work out the time evolution of a single particle state in second quantization and got something apparently contradicting with the first quantized picture. For a system with energy ...
Rupert's user avatar
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0 answers
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If system and block are released from rest, find the tension in string when the string is vertical [closed]

By using Work Energy Theorem, as well as Velocity of centre of mass, I succeeded in finding the velocities of both the ring as well as block. I noticed that there is going to be a vertical circular ...
Science Tard's user avatar
0 votes
1 answer
36 views

Strogatz's condition on definition of energy

In, Nonlinear Dynamics And Chaos, 2nd edition page 160, by Steven H. Strogatz, he writes Let’s be a bit more general and precise. Given a system $$\dot x =f(x),$$ a conserved quantity is a real-...
GedankenExperimentalist's user avatar
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0 answers
17 views

Calculating tension in a pressurized container [closed]

Suppose I have a pressurized spherical container made of 1 mm thick aluminum. The container has pressure P and internal volume V. How would I calculate the tension in the aluminum? The aim of this is ...
Varshil MVH Pets's user avatar
0 votes
1 answer
50 views

Why Consider Only Triplet States for Spin in $2$-Electron Systems?

I have a question regarding systems of 2 electrons and their spin properties. When the Hamiltonian of a system of 2 electrons can be written as a sum of two single-particle Hamiltonians that are ...
SimoBartz's user avatar
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-4 votes
0 answers
41 views

What is Suvrat Raju's point of view towards information paradox? Is it accepted by others? [closed]

Wondering what's the gist of his idea https://arxiv.org/abs/2012.05770 https://www.suvratraju.net/classes/black-hole-information-paradox/materials/lecture-1-introduction-and-two-point-qft-cor
Helen's user avatar
  • 1
0 votes
0 answers
27 views

Field theories where the potential solves a linear Schrodinger equation

Are there physical situations/applications where the potential solves a linear time-dependent Schrodinger equation, or where the gradient of a solution to the Schrodinger equation (after somehow ...
kieransquared's user avatar
0 votes
0 answers
23 views

Pressure at a point around the corner in a conical fask

I have gone through this two very informative links in understanding pressure. Weight of fluid in a conical container act entirely on the base? Pressure is isotropic But in a long conical flask which ...
soumyadip_poddar's user avatar
0 votes
1 answer
62 views

Do Helium-4 atoms behave like photons?

I know that the Helium-4 atom is a boson. Does this mean that, like photons, many Helium-4 atoms can be placed at the same point in space? How its possible? It includes fermions (Protons, Neutrons, ...
reza's user avatar
  • 197
0 votes
0 answers
8 views

Finding out the number of minima for a fourier expansion [migrated]

Suppose I have a Fourier series f(x) = $\sum_{n=1}^N t_n cos(nx)$ defined in the domain $(-\pi,\pi]$. we need to prove that mathematically we can ' at most' have N minima points excluding the boundary ...
ANIMESH GHOSH's user avatar
0 votes
1 answer
40 views

Calculating the expectation value of the angular momentum operator

I'm not looking for the exact answer to the question, but rather why a certain way of solving it is chosen. We agree on the answer, but why is the approach different. I'm afraid it's a sign of me not ...
Rommelaar's user avatar
0 votes
0 answers
49 views

The Sum of Squared Spin Operators [closed]

I heard someone casually saying that $S_{x}^2 +S_{y}^2 + S_{z}^2 =2$, as if it's common knowledge. Upon calculating it myself, I came to realize that since $S_{i} = \frac{\hbar}{2}\sigma_{i}$ and $\...
Lory's user avatar
  • 1,073
-1 votes
0 answers
29 views

What is the relationship between phase space and Jacobian in Nakahara Eq.1.15 (under this equation)?

In Nakahara's Geometry, topology and physics, under Eq.1.15 they give an equation \begin{align*} \det\left(\frac{\partial p_i}{\partial\dot{q}_j}\right)=\det\left(\frac{\partial^2L}{\partial\dot{q}_i\...
liZ's user avatar
  • 29
1 vote
2 answers
75 views

Can all physical quantities and units be derived from the seven base SI units? [closed]

I understood that from cesium that we derived the unit for second and procedurally with other universal constants we derived the other SI units. Can all other “physical” units be derived from the ...
Arden Tsang's user avatar
0 votes
0 answers
30 views

Momentum space representaion of an electron-phonon coubling Hamiltonian

I am facing a problem transforming the following Hamiltonian into momentum space: \begin{align}\hat{H} = -\gamma \sum_\alpha\sum_{i=1}^2 \hat{X}_{i,\alpha} \hat{c}_{i,\alpha}^+\hat{c}_{i,\alpha} +t\...
elfarhan's user avatar
1 vote
1 answer
34 views

Can siphons improve the efficiency of hydroelectric dams?

Suppose we have built a hydroelectric dam where the water inlet is 100m above the outlet. We can now use the gravitational potential of the water to spin a turbine. However, suppose we install a ...
orlp's user avatar
  • 162
0 votes
0 answers
25 views

How will Newton's rings look using a Concave-convex lens?

I want to examine lenses that are concave-convex (one for each side) using the Newton's rings method. I'm trying to build the theoretical model for this, but I'm quite sure that the rays of light will ...
Omer Wasserman's user avatar
0 votes
0 answers
16 views

Polarization analyzer [closed]

My understanding is that the entanglement between two photons is not broken by a polarization analyzer. One will emerge from the Y projector and one will emerge from the X projector. Is this correct?
Richard Coppack's user avatar
0 votes
1 answer
32 views

Calculating a Feynman diagram with the helicity basis

In the book by Peskin and Schroeder, they calculate the leading order diagram for the process $e^- e^+ \to \mu^- \mu^+$ (see page 136 for the labelling of the momenta). They do this in two ways: using ...
Jesse's user avatar
  • 291
2 votes
0 answers
18 views

BTZ black hole as a quotient of AdS space

I am trying to understand this paper 1 and trying to reproduce some calculations and had some questions about that. In section 3.2, page 12, eq. 3.9, the authors are writing normal geodesics of an ...
Goodfellow's user avatar
0 votes
0 answers
23 views

Where can I find the derivation of the law of mass action for liquids?

I already asked this in chemistry and all they gave me was a link to the historical derivation. https://chemistry.stackexchange.com/q/68195/ But this derivation relies on the Maxwell-Botlzmann ...
0 votes
1 answer
38 views

What would be the outcome of an experiment wherein the spin of a qubit is measured in two or more orthogonal directions simultaneously?

Out of curiosity, I am seeing the Leonard Susskind’s Theoretical Minimum lecture series on YouTube and have just started watching the second lecture. As I understand so far, the qubit can have a spin ...
Kapil Jhindal's user avatar
0 votes
0 answers
12 views

How would I calculate plasma density profile for a plasma in a magnetic field?

I want to find the density profile of a xenon gas plasma at a given pressure. My current approach is to model the plasma as a fluid and use the continuity equation below: $\frac{\partial n(\vec{r},t)}{...
MXVG's user avatar
  • 1
0 votes
0 answers
30 views

Triangle diagrams with axial currents at all vertices [closed]

I have problem with this exercise. We are considering Abelian anomaly and in particular axial currents anomalies. Consider the amplitude $ \langle 0 |T{j^\lambda_5(0)j^\mu_5(x_1)j^\nu_5(x_2)}| 0 \...
Franca's user avatar
  • 7
1 vote
0 answers
17 views

Local linearization of general Fokker-Planck equation with spurious drift?

The most general Fokker-Planck equation for a probability density $f$ over $2d$-dimensional phase space is $\partial_t f = Lf$ for the differential operator $$L f = -\partial_i(u_i f) + \frac{1}{2} \...
Jess Riedel's user avatar
  • 3,664
-6 votes
0 answers
59 views

Has anyone thought about the idea that our reality is only operating in a certain "speed range"? [closed]

I am not a physicist so I hope that this is the right place to ask. The other night after reading some of The Grand Design I was dreaming about a unified string theory type of universe where there is ...
Aleks's user avatar
  • 1
1 vote
0 answers
57 views

Energy eigenvalue of hydrogen-like atoms using Laplace-Runge-Lenz vector

I have a basic question about a few calculations involving the quantum mechanical Laplace-Runge-Lenz vector. In classical mechanics there is the Laplace-Runge-Lenz vector, which for a hydrogen-like ...
Jonathan Huang's user avatar
1 vote
2 answers
93 views

Validity of $\mbox{d}H/\mbox{d}t=\partial H/\partial t$ for dissipative systems

It' well known that in Hamiltonian formalism one has $$ \frac{\mbox{d}H}{\mbox{d}t} = \frac{\partial H}{\partial t}.\tag{*} $$ One proof can be found here. Therefore, the total change of energy during ...
Luessiaw's user avatar
  • 685
1 vote
1 answer
30 views

Cause of Coordinate Acceleration in Free Fall [duplicate]

So I understand that objects in free fall are in an inertial frame, at rest in terms of relativity. However, from a person on the surface of earth, a falling apple is accelerating constantly until it ...
Marco Chacon's user avatar
-1 votes
0 answers
42 views

What kind of law can accurately describe atomic nuclei? [closed]

I understand that atomic nuclei are much too dense to behave as an ideal gas. Are they degenerate? I would assume so (similar to neutron stars), but couldn't find any laws that would accurately ...
Joe Peters's user avatar
0 votes
2 answers
43 views

Is simple sound transmission in matter normally 100% efficient or is there "leakage" to heat even when there is no damage or destruction of medium

Specifically I was wondering for instance in a perfect gas or real gas or water or steel does the medium absorb some sound as perhaps thermal energy, or can it always travel without losses through the ...
Bryan Major's user avatar
1 vote
1 answer
44 views

Relative acceleration, mechanics

Consider a system of two objects with mass $M, m$ as presented below. Assume that there's no friction between both the surface, M and between M, m. I'm asked to find the acceleration of m, M using ...
X4J's user avatar
  • 111
-1 votes
0 answers
22 views

How to find resonant frequency of this spherical mass? [closed]

how to find resonant frequency of this spherical mass in the diagram above? and also, the resonance frequency of mass on an elastic beam with viscoelastic contact with the beam
Hassan's user avatar
  • 1
5 votes
2 answers
267 views

Relation between energy and time

I would like help in understanding something that has been causing me a lot of trouble recently. Why is energy always related to time in physics. Whether it is in the 4-momentum, the energy-time ...
Lucas's user avatar
  • 147
1 vote
0 answers
17 views

Is X-Ray-Emission-Containing Phosphorescence possible or is it limited to Immediate-Emission XRF?

This was a random thought that I wanted to follow up on. I know some materials can take in and kick out X-Rays in XRF (Though most x-ray scintillators tend to emit mostly visible light, not x-rays). ...
Mister SirCode's user avatar
3 votes
0 answers
43 views

Do optimal Lieb-Thirring constants have physical meaning?

In their proof of stability of matter Lieb and Thirring used a particular set of inequalities. Namely, if $H=-\Delta+V(x)$ is a Schrödinger operator, then the sum of (powers of the absolute value of) ...
Severin Schraven's user avatar
-1 votes
1 answer
63 views

Can you calculate the radius of a hypothetical singular surface inside a black hole from observing changes to its linear momentum?

Say there is a ball of unknown radius surrounded by a bubble. The ball represents a hypothetical singular surface inside a black hole and the bubble represents the event horizon. If you threw marbles ...
user414142's user avatar
1 vote
2 answers
66 views

Charging a capacitor without closing a circuit

It might sound absurd but is it possible to charge a capacitor solely by connecting the positive terminal of a battery to one plate of the capacitor and the negative terminal of another identical ...
Nightwing's user avatar
  • 417
4 votes
2 answers
335 views

Spring potential energy, conversion

I have a physics problem in my book, where a spring is compressed and a ball is laying in the end of the spring. When the spring is released the ball will reach a certain speed. In the solution it ...
Ryan Johansson's user avatar
0 votes
0 answers
45 views

Kramer's degeneracy and ambiguity in time-reversal operator

To my understanding, time reversal symmetry can be represented by an anti-linear operator $T=U\mathcal{K}$, where $U$ is a unitary operator and $\mathcal{K}$ represents complex conjugation. This ...
TopoLynch's user avatar
  • 503

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