0
votes
1answer
92 views

How to calculate precipitation chance with basic weather data?

I would like to know if there is any algorithm which allows us to calulate precipation chance with following data: temperature, humidity, illuminance (in lux) and pressure. I've searched it in google, ...
0
votes
0answers
20 views

Imaginary time formalism

Consider a function of energy-scale $\tilde{F}(k)$ and its fourier transform in time as $F(t)$ (as energy-scale is the fourier-conjugate of time in Minkowski space). Then we have \begin{equation} ...
0
votes
1answer
43 views

Do wormholes violate causality [duplicate]

Does opening and closign a wormhole to send a message within seconds across the galaxy violate causality? Wouldn't different observers disagree about the order of events and what effected what? Is ...
0
votes
1answer
13 views

Dynamic response of temperature change when identical fluids flowing mix together

As shown in the below figure , there is a mixing of a fuel in a system. the mass flow rates m1,m2 are different, the pipe diameters are all equal but are different in length.I need to get the ...
-2
votes
0answers
14 views

Magnetic field due to closed donut

How to find magnetic field due to a torroid? Thanx in advance. Im studying for jee and our prof tried to teach it but i didnt understand.help please
-3
votes
0answers
8 views

components of vector regarding the direction of acceleration

The steps of how to calculate th direction of acceleration Example Calculate the direction of the acceleration when acceleration has an eastward component of 2.5m/s squared and nortward component of ...
1
vote
2answers
821 views

Finding Electric Field outside a Charged Cylinder

I'm trying to solve a problem that involves finding the electric field due to a uniformly cylinder of radius $r$, length $L$ and total charge $Q$. Well, my thought was: if I am to use Gauss' Law, I'll ...
2
votes
0answers
227 views

Can spheres leaking charge be assumed to be in equilibrium?

I am struggling with the following problem (Irodov 3.3): Two small equally charged spheres, each of mass $m$, are suspended from the same point by silk threads of length $l$. The distance between ...
0
votes
1answer
19 views

Density and Wave Speed

For a string, the formula for wave speed is $v=\sqrt{\frac{T}{\mu}}$, where $\mu=\frac{m}{L}$. The greater the linear density, the more massive the string is per unit length, the more inertia it has, ...
2
votes
1answer
39 views

Uniformly charged sheet and metal rods

A friend of mine asked me a question. Suppose there are two metal rods which are placed in front of a uniformly charged non-conducting plane one after other with their length perpendicular to the ...
-1
votes
0answers
18 views

Unable to solve cable theory equation correctly

First time posting, let me know if I'm in the wrong board. I tried this over on the math board and was redirected here. In my spare time I enjoy reading outside of my field (software development). ...
0
votes
2answers
92 views

Newton's Laws ( Little Philosopical )

Suppose we are living in a universe that in that universe when you release a particle in the empty space, this particle stay forever where you release it. Which is not the case in our universe. I'm am ...
0
votes
1answer
19 views

Equipartition Theory at room temperature.

I read a statement about participation theory. The equipartition theorem is generally valid only at high temper- ature, so that the thermal energy is larger than the energy gap between ...
3
votes
2answers
359 views

Is there a way to calculate the photoelectric effect in QED via a Feynman diagram?

The photoelectric effect is the historic origin of the quantum particle description of light. From it we learn that when light is shone onto a metal single photons interact with single electrons in ...
-1
votes
0answers
24 views

Directional derivative of the Ricci scalar in the direction of a Killing vector field

Do I need the Levi-Civita connection for the directional derivative in the direction of a Killing vector field of there curvature scalar to be 0? EDIT: Let $K$ be a Killing vector field and $R$ the ...
0
votes
0answers
7 views

Potential of a point charge in dielectric

My configuration is a point charge embedded in a finite dielectric geometry. I have to calculate the potential of the point charge only within the dielectric device. How should I do this?
5
votes
4answers
1k views

Why do solar cells have a window layer on top of the absorber layer and not below it?

In solar cells there is a p-n junction. P-type semiconductor (for example CdTe) is often absorber layer because of its carrier lifetime and mobilities. In case of CdS/CdTe,* CdS is n-type window layer ...
9
votes
2answers
486 views

What is the mechanism by which magnetic fields do work?

I've seen some conflicted answers to this question in texts and on the web, in the case of a dipole, for example. Do magnetic fields do work directly, or is it their induced electric fields that do ...
0
votes
0answers
18 views

Why does the weaker force deform the solid body? Elasticity problem

It's about a problem in which two forces are pushing a cylincer in different directions. Ïnside the cylinder some reactions forces appear.Here's the representation of a mass dm since it's very small. ...
6
votes
1answer
243 views

Casimir Forces and its associated Feynman Propagator

This is a continuation to my previous question, in which I began an attempt solve the Casimir Force problem using path integrals. As one of the answers there suggest I solve the Feynman propagator ...
0
votes
1answer
66 views

M-theory and Mathematics

If the framework of M-theory is the right path for a unification of gravity with quantum mechanics, is it obligatory to believe that, at a certain level, reality is not just easily describable by ...
0
votes
1answer
57 views

Lippmann-Schwinger equation and $T$ expansion

Lippmann-Schwinger equation, in operator form, is: $$ T=V+V\frac{1} {E-H_0+i \hbar \varepsilon} T=:V+V\Theta_0T, $$ where $H_{tot}=H_0+{V}$ is the hamiltonian ($H_0$ is the free particle hamiltonian ...
2
votes
1answer
116 views

Would the hot windows break? [on hold]

I have a question that I was thinking about for a long time. I live in Kuwait and in the summer season the weather reach 50°C which is extremely hot specially inside a car. What if I was able to ...
-3
votes
0answers
12 views

Optical fibre numerical problems [closed]

(a) What is the need for a cladding layer on the core of an optical fiber other than mechanical strength? (b) Assuming a fiber that is kept stra ight and is of length L, find the ...
0
votes
0answers
36 views

River Boat Problem with a Twist [closed]

I am trying to solve the following river boat problem. A river of width $w$ is floating such that the stream velocity varies with $y$ as $$v_R=v_0(1+(\frac{\sqrt 3 - 1}{w})y)$$ where $y$ is ...
0
votes
0answers
23 views

Need reference on the minimum moment of inertia [duplicate]

I would like to know if there is a book on classical mechanics about the following Moment Of Inertia About Centre of Mass
0
votes
2answers
32 views

Horizontal and vertical acceleration of a ball on a slope?

I understand that you resolve the components of the balls weight parallel and perpendicular to the slope in order to calculate the force due to gravity that actually acts down the slope. The ...
0
votes
0answers
25 views

What is the maximum level of heat that can be reached? [duplicate]

Heating is what everyone knows about . But does it have any limits . How much hot can anything become?
1
vote
0answers
89 views

Trebuchet launch into space

I was reading some questions on your site about using a Trebuchet to launch a payload into space. Would it be possible to use the same sort of principle, but to have, say a 100 mile steel cable ...
0
votes
1answer
47 views

What will happen if all the population all over the world jumped together at the same time in sea? [duplicate]

What can happen if a magnitude of such huge force is applied over the sea water of earth? Force applied will be average mass of each person *7 billion *9.8 .
12
votes
2answers
279 views

Was Leverrier-Adams prediction of Neptune a lucky coincidence?

According to historians both Adams and Leverrier used Bode's law to guess the distance to Neptune, which led to a vast overestimation of its orbital period (Adams - 227 years, Le Verrier - 218 years, ...
-6
votes
0answers
52 views

Theoretical physics [closed]

Hi every one I am student who has a high interest in the Ising model. Please I have a question and I hope someone can help me
7
votes
1answer
62 views

Without using rotational mechanics, why does a gyroscope precess the direction it does?

When a top is spun, it will precess in some direction, either clockwise or counterclockwise. It's possible to find out which way using $\boldsymbol{\tau} = d\mathbf{L}/dt$ and $\boldsymbol{\tau} = ...
-1
votes
0answers
21 views

What is the time dilation effect in the presence of two equal and opposite gravity sources?

If one were between two equal and opposite gravity sources, would the time dilation effect cancel out, since the acceleration is cancelled out?
1
vote
0answers
15 views

Finding canonical transformation using type 3 generating function

Question: For a system with one degree of freedom, a canonical transformation $Q(q,p), P(q,p)$ obtained by a type 3 generating function satisfies $Q = e^t q^{1/2}\cos p$. Find the most general form ...
0
votes
3answers
78 views

What is the relationship between entropy and work? [closed]

Can someone explain the relationship between entropy and work? I've been reading my textbook and looking online but I feel like I'm missing something. Can someone explain it in layman's terms :)
1
vote
1answer
56 views

Can 4 collinear planets exist?

Imagine 4 planets, A has moon a and B has moon b. A and B are binary planets. Is it possible that a and b and A + B all have same the period, so that the 4 planets are collinear?
1
vote
1answer
323 views

Can there be force without motion?

I am confused. Can you have a force or tension without motion? Take for instance two robots with jet packs connected via a cord, each is flying in opposite directions. The tension of the cord is ...
1
vote
0answers
16 views

Electric field operator in 2D geomatry

In the free field (3D), transverse electric field operator is given by the below expression; $$e^{\bot}(\textbf{R}) =i \sum_{\textbf{p},\lambda}\Big( \frac{\hbar cp}{2V\epsilon_{0}}\Big)^{1/2} ...
0
votes
1answer
19 views

Vector potential in gauge transformation

While applying Gauge transformation, $\psi\prime = U \psi$ , where $ U= e^{i q \lambda(x)}$ , transformation law for "Vector Potential" comes out to be : $$ A_{\mu}\prime= ...
1
vote
2answers
678 views

How do magnets work?

I've read a classbook on the field theory (including EM): it perfectly describes quantitive patterns in EM-theory, but I have no luck understanding how and why it works. I mean, magnetic substances ...
3
votes
3answers
590 views

Why is momentum quantized in a 1D box even though the operator doesn't give eigenstates?

We don't get eigenstates of momentum when we operate momentum operator in the wave function of particle in a 1D box problem yet we say momentum is quantized in this situation. Why is it so?
3
votes
2answers
71 views

Is there a mathematical relationship between Legendre conjugates and Fourier conjugates?

In quantum mechanics, there is an uncertainty principle between conjugate variables, giving rise to complementary descriptions of a quantum system. But the variables are conjugates in two different ...
1
vote
1answer
23 views

Find the separation distance for a line of oil being squashed between two flat plates

I was wondering if someone could give me some help on how to start this problem, I'm really struggling to get my head around it. A long line of oil is being squashed between two flat plates of length ...
1
vote
0answers
30 views

Null geodesic equation with affine parameters [duplicate]

A photon's geodesic equation is defined by re-parameterizing the geodesic equation to some parameter other than proper time. This is done because $ds=0$ for the photon. Again if we use affine ...
-1
votes
0answers
21 views

Proof of transformation between contravariant and covariant components of vector [on hold]

What is the proof of the relation ${g^{ir}g_{rj}=\delta^i_{j}}$ where ${g}$ is the metric tensor and ${\delta}$ is the Kronecker delta. EDIT:The operations is known as equivalent to raising and ...
1
vote
1answer
49 views

Completeness relations of eigenstates in the Heisenberg picture

I've been reading Srednicki's introduction to path integrals and I'm slightly unsure of the notation that he uses for the completeness relation of position eigenstates in the Heisenberg picture. In ...
1
vote
1answer
190 views

Wormholes and the illusion of time?

I was watching a video on Youtube by Brian Greene, "the illusion of time."http://www.youtube.com/watch?v=j-u1aaltiq4 In that video, he introduces to me the idea of a "brane," or a slice of the ...
1
vote
0answers
31 views

What is special about quantum entanglement? [duplicate]

Get two pieces of paper. In secret write the same number on both papers. Transfer one paper to the Moon. Look to the paper which is left at the Earth. Voila! We know what is on the Moon paper. The ...
-7
votes
0answers
21 views

what health per-captions should be taken for theoretical senerios [on hold]

so been working on some detail research and i been having some trouble since have of the experiment affects are still only theoretical but let me explain as best i can. so lately i been working with a ...

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