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Can anyone suggest which piechoelectric material is the cheapest

can anyone suggest which piechoelectric material is the cheapest. Or maybe there are similar materials that have the ability to respond to pressure? Please excuse my english))
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0 answers
3 views

Question about a problem involving electrostatics

I need help with the following problem: An uncharged ball of mass m = 1 g hangs on a thin inextensible thread of length L = 10 cm in air. A second ball with charge Q = 2 · 10−8 C is brought into the ...
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0 answers
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When deriving the analytic representation of Fock states , why doesn't the $\hat{P}$ operator act on the ground state?

Starting with \begin{align*} |n \rangle=\frac{1}{\sqrt{n!}}(\hat{a}^{\dagger})^{n}|0\rangle \end{align*} and \begin{equation} \psi_{0}(x)=\left(\frac{m\omega}{\pi\hbar}\right) ^{\frac{1}{4}}\...
1 vote
0 answers
11 views

Measurement of the spin of the EPR pair in two orthogonal directions and how did Einstein tackle this?

Let us consider two types of measurement in the EPR experiment. In Bohm's description of this experiment, the state of the electron-positron (called the EPR pair) is given by $$ |{\rm EPR} \rangle =\...
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0 answers
6 views

Magnetostatics: Compute internal magnetic field of a paramagnetic fluid

I have a question about calculating the internal magnetic field of a paramagnetic fluid. Assume that I apply an external magnetic field in the $x$ direction, equal to $H_{ext.,x}$ = 1 amp/m, on a ...
1 vote
1 answer
15 views

What does volume parameter for a real gas equation mean for a fluid flowing in a pipe?

I want to understand what the volume means in a $(p,v,T)=0 \ $, for a system of real gases flowing in a pipe. Will it be that since the fluid is flowing, $V$, will be the local volume in a given ...
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1 vote
1 answer
29 views

Tension in moving chain

Suppose I have a chain in equilibrium position (a catenary). The only force acting on it is gravity. Now, say that I move this chain in such a way that every point traces this catenary. Basically, the ...
1 vote
0 answers
26 views

Can QFT not be done with only tree diagrams?

Here's the methodology: We first write out the equation of motion for $\phi(x,t)$ in the Heisenberg picture. This is identical to classical field equation. Now, we solve the equations perturbatively, ...
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0 votes
1 answer
23 views

Does Plasma Contain Fire?

I've always seen plasma as (in a dumbed down state) a combination of electricity and fire. I know the electricity part is correct (I hope) but I don't know about the fire part. Could someone confirm ...
0 votes
1 answer
18 views

Why is the conductor oscillating? [closed]

Hi, what I am wondering is that why does the conductor oscillate? I picked B because the way the answers were set sort of leads you to pick it(Its correct according to the answer sheet). But I feel ...
1 vote
0 answers
23 views

How do you show that the analytic wavefunction of the energy eigenstates of the quantum harmonic oscillator contains Hermite polynomials? [closed]

Starting with \begin{align*} |n \rangle=\frac{1}{\sqrt{n!}}(\hat{a}^{\dagger})^{n}|0\rangle \end{align*} and \begin{equation} \psi_{0}(x)=\left(\frac{m\omega}{\pi\hbar}\right) ^{\frac{1}{4}}\...
1 vote
0 answers
20 views

Point Particle Energy Momentum Tensor from Lagrangian Density

Given the Lagrangian density of a point particle $$\mathscr{L} = - m \int \sqrt{-g_{\alpha \beta}\dot{z}^{\alpha}\dot{z}^{\beta}} \delta^{(4)}(x,z) d\lambda$$ we could derive the energy momentum ...
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0 answers
17 views

Confusion about a boundary condition (steady heat conduction)

Given a composite material composed of two materials each having different thermal conductivities and heat flux vectors. This leads us to write the two properties as position dependent. One thing I ...
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0 answers
12 views

Momentum Operator in Anti de Sitter spacetime

Im studying the dirac equation in two dimensional anti de sitter space with metric \begin{align*} g_{\mu\nu}= -\frac{L^2}{\cos^2(\theta)}\left( \begin{array}{rr} 1 & 0 \\ 0 & -1 \end{array}\...
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1 vote
1 answer
51 views

How objects are kept free falling in the LISA experiment?

I'm watching a video about the LISA experiment, which will be used to detect gravitational waves. In there 3 space stations will be launched and will follow the Earth in its revolution around the Sun. ...
0 votes
1 answer
12 views

Relationship between net torque and net force in constrained systems

If the movement of the rigid body is "constrained", let's say a ladder leaning against a wall, would net torque $= 0$ always imply net force $= 0$? In most physics questions, torque and ...
0 votes
0 answers
31 views

Spacetime curvature due presence of mass [closed]

We can calculate the spacetime curvature due the mass of Earth using the formula: $$ \frac{1}{R_c{}^2} = \frac{2GM}{c^2R^3} $$ where $R_c$ is the curvature radius. Now beyond the arithmetic result (...
4 votes
0 answers
22 views

How to efficiently get the largest probabilities / amplitudes of a quantum state stored as an MPS?

Let's say, that we have the following pure, superposition state $$ |\psi \rangle = \frac{1}{\sqrt{2}}|000001 \rangle + \frac{1}{2}|101101 \rangle + \frac{1}{2}|100100 \rangle $$ stored in the MPS form....
0 votes
0 answers
32 views

Is it possible that space-time needs minimal energy to bend?

In the photoelectric effect, a metal does not emit electrons until the energy of the beam irradiated to it is more than its minimum energy value. I was thinking, is it possible that space-time also ...
1 vote
1 answer
17 views

Fast solution for a nonlinear system of 3 equations of degree 3? [closed]

I have a nonlinear system of 3 equations with 27 constants and 3 unknowns x, y, z ...
1 vote
0 answers
21 views

How would a newtons cradle work with varying velocities

I've recently learnt that during elastic collisions between bodies of equal masses, the velocities are exchanged, which is how a Newtons cradle works. However, I was wondering what would happen if ...
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1 vote
0 answers
32 views

What is the relation between time and temperature for Universe?

I am trying to pass cosmology subject in my university and have to calculate temperatures in different moments of history, for example $10^{-30}s,10^{-20}s$ after big bang. I assumed that for ...
1 vote
1 answer
72 views

Why does small work done mean $dw=f.ds$ and why not $dw=df.ds$ and why not $dw=s.df$?

Work, power and energy questions. Why does small work done mean: $$dw=f.ds$$ and why not: $$dw=df.ds$$ and why not: $$dw=s.df \ \ ?$$
2 votes
0 answers
34 views

Why am I conducting electricity when using two laptops?

I've recently started using two laptops, often when I use it, they're both used side by side both plugged into the same extension lead. The Mac has a metal body and the other laptop has a plastic body ...
0 votes
0 answers
10 views

Measurement of Einstein's-View-Of-Gravity from GNSS Data [closed]

I am a newbie. Is it possible to measure Einstein's-View-Of-Gravity from GNSS Data? Please advise. Thanks.
1 vote
1 answer
49 views

Blue glow around astronaut

What is causing the apparent blue tinge around the astronaut and instrument in these images taken from Apollo 12? Source: NASA archive (Images AS12-46-6826, AS12-46-6816, AS12-46-6847)
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0 answers
16 views

If we oscillate antenna [closed]

If we oscillate reciever antenna with an omega frequency, will it create (recieve) a current with it's own frequency?
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0 votes
0 answers
17 views

Why electric potential is separable?

In Electrostatics, if we consider a region without charges the electrostatic potential $V$ obeys Laplace's Equation $\nabla^2 V = 0$. We can tackle this with separation of variables. In cartesian ...
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0 answers
10 views

Can a static electric charge stably levitate using the superposition of electric potentials?

According to Earnshaw's theorem for electrostatic fields a charge cannot be kept in stable equilibrium by purely electrostatic fields. The mathematical proof for this is usually as follows: if the ...
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-1 votes
0 answers
24 views

Would two non-colliding objects traveling at speeds greater than half the speed of light, in opposite directions, would see each other as tachyons? [duplicate]

Lets say ship A and B are both traveling at the speeds "c/2 < speed < c", in opposite directions but not on a collision path. At the time the two ships pass each other, would ship B ...
0 votes
0 answers
14 views

About $F_5$; equations of motions and Lagrangian

Recently, I heard that there exists some physical system that we know its equations of motion but not knowing Lagrangians. One particular example is M-theory. For example, the self-dual form $F_5$ is ...
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-1 votes
0 answers
30 views

Why I am not getting answer with my method? [closed]

I have seen the solution to this problem. But I am curious to know why my method is not leading me to the answer. Kindly check my method. Question My method ...
0 votes
0 answers
15 views

Experimentally verifiable predictions of noncommutative geometry?

My very limited understanding of noncommutative geometry (NCG) is that it generalizes the concept of manifolds in such a way that the algebraic properties of differential forms are retained without ...
0 votes
2 answers
16 views

Question regarding understanding Dipole Moment

I am trying to understand the meaning of the term Dipole Moment,every definition or physical explanation involves some kind of hand wavy explanations ,I would like some concrete intuitive explanation ...
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0 votes
0 answers
29 views

Which way do excited electrons prefer, to go directly onto ground state or to go through intermediate energy level?

Do excited electrons prefer to go directly onto the ground state or to go through an intermediate energy level? (I know it depends on the probability weather electrons take a direct way to the ground ...
1 vote
0 answers
14 views

Electric fields affecting recombination of virtual particle pairs

Besides the Schwinger effect, whereby a strong enough electric field can cause the creation of virtual particle pairs in the quantum vacuum, I have also read that a suitable electric field is able to ...
1 vote
0 answers
24 views

Disgreement with Birrell's and Davies' book on QFT in curved space

In B&D (Birrel and Davies) and more specifically, at the end of Chapter two, the authors define the non-zero temperature Green functions, as $$G_{\beta}^+(x,x')=\langle{\phi(x)}\phi(x')\rangle_{\...
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-1 votes
0 answers
15 views

Relation between acceleration vectors from ground frame and a frame rotating relative to ground [closed]

How do we find out the relation between acceleration vectors from ground frame and a frame rotating relative to ground. I have been trying it for hours with little to no success so any help would be ...
0 votes
1 answer
27 views

How can velocity of water remain constant for a vertical cylindrical tube?

I have got a question in the Physics textbook which is as follows: Water enters through end A with speed v1 and leaves through end B with speed v2 of a cylindrical tube AB. The tube is always ...
1 vote
2 answers
41 views

Four vectors and coordinates

Hartle, gravity. Chapter 5 A four-vector is defined as a directed line segment in four-dimensional flat spacetime in the same way as a three-dimensional vector (to be called a three-vector in this ...
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2 answers
36 views

Why electric field and magnetic field are in phase in electromagnetic waves?

I can understand in mathematics but could you please explain it's physical significance (such as from the energy perspective)?
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0 votes
2 answers
44 views

Are these two "notations" the same? [closed]

Say we have a tensor $T^{\sigma\tau}$ and I want to now how it transforms, the transformation coefficients in terms of Lorentz transformation matrices would be: $$T^{\mu'\nu '} = L^{\mu '}{}_{\sigma}L^...
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1 vote
1 answer
18 views

Find the density of liquid Y

While solving the question, I had some confusion, that we know net pressure at equal depths must be equal in fluids so if we try to equate the pressures at depth of 8cm (instead of the conventional 10 ...
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1 vote
1 answer
107 views

Book recommendation for blackhole thermodynamics?

So I was reading this wonderful article about blackhole thermodynamics. https://hapax.github.io/physics/teaching/bh-thermo/ Can someone recommend a book which covers all 4 laws of blackhole ...
0 votes
0 answers
28 views

The conflicts between the Bell inequality and local interactions [closed]

The Nobel prize in physics 2022 was awarded to Aspect, Clauser and Zeilinger for their contributions to "experiments with entangled photons, establishing the violation of Bell inequalities and ...
-2 votes
0 answers
19 views

How far from earth could the the Tsar bomb blast be detected [closed]

Tsar Bomba, 56 megatons, (could have been 100 megatons), with an air burst,-how far away could the flash be detected if using current earth tech? -did we attract aliens?
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0 answers
11 views

How to check if an equation is represents a one dimensional traveling wave? [closed]

I want to check if the following equation represents a one dimensional traveling wave. f(z,t)=$e^{-az^2-bt^2}$ I know the general form of a traveling wave is y=$f(x+vt)$ However, I'm having a hard ...
0 votes
1 answer
16 views

Deriving the plane progressive wave equation $y=a\sin(kx−wt)$ [closed]

How do you derive the plane progressive wave equation $y=a\sin(kx−wt)$? What equations do you use to derive the wave equation and how do you do it?
0 votes
1 answer
26 views

A unit base vector after the coordinate system is rotated is $(\dfrac{\sqrt{3}}{3},\dfrac{\sqrt{3}}{3},\dfrac{\sqrt{3}}{3}) $, then the other two? [closed]

The three-unit basis vectors of the old coordinate system are: $$ \begin{align} \mathbf{i}(1,0,0)& \\ \mathbf{j}(0,1,0)&\\ \mathbf{k}(0,0,1)& \end{align} $$ Now rotate the entire ...
-1 votes
0 answers
19 views

Conceptual homeworks problem ~ help [closed]

After finishing the study of the integral and the differential approach for fluid dynamics I am having some difficulties in getting started in answering this problem I found. Would it be possible to ...

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