7
votes
1answer
268 views

Is it possible to determine particles' velocities from their crossings on a ring?

2 particles are constrained to move in a ring. Both particles begin moving at $t=0$ from $p=0$, each particle moving in the opposite direction of the other. It is known that they are moving at ...
0
votes
1answer
21 views

Books on quantum mechanics with intuition [duplicate]

So, I know that there are a lot of questions about good books on quantum mechanics and I have read each one of them, and I go on and bought Griffiths' Introduction to Quantum Mechanics. But the fact ...
0
votes
0answers
2 views

The significance of the pressure term within the momentum-energy tensor

Taking the momentum energy tensor T$_{\mu\nu}$, I am trying to understand the origin and significance of the pressure term p included within it. I am also confused as to where potential energy is ...
0
votes
2answers
20 views

Molecules from atoms

Why does two oxygen atoms combine to form a molecule and not 3 or 4?Also why does one sodium and one chlorine atom combine to form NaCl while two chlorine atoms are required to combine with one ...
-1
votes
1answer
21 views

Do shadows have mass?

It sounds like a joke but I just want to know if shadows have mass, since shadows are formed when there is blocking of light. It forms a black pattern with no energy therefore it has no mass.
0
votes
0answers
9 views

Need help in understanding tensorial simplification in a special case

The Lagrangian of N=2 supergravity's important terms for my purpose are (hopefully I simplified this correctly): ...
0
votes
3answers
17 views

Foci of elliptical path

I have read the Kepler's laws of motion where I came across the term foci of elliptical path. But what is really a focus? Can anyone please explain what is a focus (maybe with a diagram) and why a ...
0
votes
1answer
19 views

Voltage and volume, same SI symbol, how to discern between the two? [on hold]

Both are SI quantities that use the same symbol, namely $V$. It annoys me that I might be working with the wrong unit even though it's easy to see if it's voltage or volume by looking to the whole ...
0
votes
0answers
9 views

Initial current, RC Circuit

The task goes like this: The voltage between the points A and B, in the circuit diagram below, is 100 V. What's the initial current through the resistor when we close the switch S? (Other components - ...
7
votes
1answer
94 views

Wavy stream of liquid

When pouring a liquid into a glass some streams have a wavy shape, like the one in the following photo: (Couldn't find a better picture, sorry.) What causes the stream to be of such a shape?
-1
votes
0answers
10 views

Finding displacement of spring

Q) A block lies on a horizontal frictionless surface, and the spring constant is 50 N/m. Initially, the spring is at its relaxed length and the block is stationary at position x=0. Then an applied ...
11
votes
3answers
12k views

Why does water pouring from a glass sometimes travel down the side of the glass?

If you have a glass of water, say, three quarters full and you pour it at an angle of say, $45^{\circ}$ with respect to the the table, the water comes out of the glass and goes directly down towards ...
10
votes
2answers
185 views

Why pouring milk from a height makes a chain shape?

I have noticed a chain-like shape when milk is poured from a height into a cup. Actually the chain pattern repeats itself after some distance and again till it reaches the milk in the cup. Any ...
0
votes
0answers
16 views

Solving the Three-body problem numerically

I want to create a program in $Mathematica$ that solves numerically the Three-body problem by Euler-Lagrange's equations. I was searching some methods to sucessfully do it. So I found a way to solve ...
2
votes
2answers
1k views

Coupled quantum harmonic oscillator

Given the following Hamiltonian for two identical linear oscillators with spring constant $k$ and interaction potential $\alpha x_1x_2$; I was asked to find the expectation value $\langle ...
3
votes
2answers
63 views

If mesons were stable could they form atoms?

if there were stable enough mesons similar to protons and neutrons could they capture electrons to form exotic elements. if not why is this not possible?
0
votes
0answers
11 views

The minimum force required to lift a triangular prism

If I have an isosceles triangular prism of mass m with the angle at the top being $2\theta$ I want to work out the minimum force I would need to apply to the upper faces to lift the prism. Lets say ...
7
votes
9answers
1k views

Did relativity make Newtonian mechanics obsolete?

Did Einstein completely prove Newton wrong? If so, why we apply Newtonian mechanics even today? Because Newton said that time is absolute and Einstein suggested it relative? So, if fundamentals are ...
0
votes
0answers
20 views

Suggestions for GR solved problems books

Study Topic: General Relativity I'm looking for a recommendation for either a dedicated problems and solved solutions book or, failing that, a textbook with a separate comprehensive solutions ...
7
votes
3answers
2k views

Is the speed of sound almost as high as the speed of light in neutron stars?

Have you ever wondered about the elastic properties of neutron stars? Such stars, being immensely dense, in which neutrons are bound together by the strong nuclear force on top of the strong gravity ...
0
votes
1answer
95 views

Asymmetry in magnetic field direction of an electric wire

The simplest magnetic field is that of an infinitely long wire with uniform current. It does enjoy radial symmetry about the wire and has the variation as 1/r. To find the direction of the resulting ...
0
votes
1answer
13 views

How can electric field accelerate fog dissipation?

I should emphasize that I view the problem as a 'research' rather than a 'textbook' level. However, as I am almost unfamiliar with the subject it may be that the answer is elementary and well-known. ...
0
votes
0answers
7 views

Scattering and form factor

In Introductory Nuclear Physics by Krane (there's a PDF online), it is mentioned electron scattering on the nucleus to get a picture of the latter's shape, e.g., its radius. It is said the probability ...
0
votes
0answers
37 views

Contraction of Kronecker delta = 4

This suggests, as a shortcut notation, the concept of lowering indices; from any vector we can construct a (0, 1) tensor defined by contraction with the metric: $$A_\nu ≡ g_{\mu\nu}A^\mu$$ so that ...
0
votes
2answers
51 views

Violation of conservation of energy?

Imagine a perfectly spherical mirror with 100% reflection. Imagine a point source of light in the center. The point source keeps radiating light. Will the light undergo destructive interference ...
81
votes
0answers
4k views

Superfields and the Inconsistency of regularization by dimensional reduction

Question: How can you show the inconsistency of regularization by dimensional reduction in the $\mathcal{N}=1$ superfield approach (without reducing to components)? Background and some references: ...
0
votes
2answers
22 views

What does “simultaneously” mean in relation to a detonation shockwave?

I understand that the difference between a deflagration and a detonation is that the reaction front of a detonation moves faster than the speed of sound in the material, which means that the pressure ...
0
votes
1answer
9 views

How can a reversible adiabatic expansion not increase entropy?

In the second stage of the Carnot cycle, a gas is thermally insulated and allowed to expand and do work on the piston. I understand the reason people give is that because entropy is $\,dS = \,dQ/T$ ...
4
votes
0answers
28 views

Why are $W$ bosons massless above electroweak scale?

Because of the Higgs mechanism, one must replace the Higgs field $\phi$ with $\phi_0 + \phi_1$ where $\phi_0$ is the vacuum expectation value. As far as I understand, the $\phi_0$ gives the mass term ...
0
votes
1answer
23 views

Density of states of 3D harmonic oscillator

for the first red box, shouldn't be $\epsilon^2 =\epsilon_{n_x}^2 +\epsilon_{n_y}^2 + \epsilon_{n_z}^2 + 2\epsilon_{n_x}\epsilon_{n_y} + 2 \epsilon_{n_x}\epsilon_{n_z} + ...
3
votes
1answer
90 views

Why are nonrelativistic methods used in binary pulsar systems (gravitational waves)?

Although gravitational waves are a subject of the General Relativity, why do most books use Newtonian equations of motion for power radiated and rate of change of eccentricity calculations? In most ...
0
votes
1answer
13 views

How often does a GPS receiver receive microwave signals from satellites?

I'm just finishing up a report on the mathematics of GPS, but I'm not sure how to determine how often a GPS receiver actually receives data from the satellites. If a satellite send out its microwave ...
20
votes
8answers
2k views

Is it possible to blur an image in such way that a person with sight problems could see it sharp?

If someone has short or long sight, is it possible to tune image on a computer monitor in such way, that a person could see it sharp as if they were wearing glasses? If not, will 3d monitor make it ...
0
votes
0answers
4 views

Atomic flux on the surface?

I have a surface which is made up of two triangles of unequal areas. I impinge a single atom on the surface at a certain angle at a certain time interval. As flux is atoms/unit area/unit time. In ...
1
vote
2answers
123 views

Instant centre of rotation for two connected gears

The two gears are have the angular velocities $\omega_1$ and $\omega_2$ respectively with respect to $Oxyz$. The task is to determine the angular velocity $\boldsymbol{\omega}$ of the arm ...
5
votes
2answers
210 views

Kerr Metric in Orthogonal form

I've seen the Kerr metric usually presented in the Boyer-Lindquist coordinates where there is a cross term in the $d\phi$ and $dt$ term. I've done a good bit of searching and cannot find any ...
0
votes
0answers
12 views

air pressure in elevator

An elevator is accelerating upward. 1-How will the air pressure(P0) change? Will it decrease, increase or it doesn't change? WHY? 3- How will the formula of pressure(P=pgh+P0) change? 4- If a ...
0
votes
1answer
24 views

Can someone give an intuitive understanding of Fano Resonance?

I'm reading about Fano Resonance. The line that almost every source I can find gives is something like (from the wiki): The Fano resonance line-shape is due to interference between two ...
0
votes
5answers
43 views

Can dark matter be converted to dark energy?

According to energy mass conversion law, mass can be converted to energy. So is it possible to convert dark matter into dark energy?
9
votes
1answer
349 views

Lagrangian Coordinates in Fluid Flow

I apologize if this is not the right place to ask this question: I am currently reading a paper by Y. Brenier, where for the fluid flow he introduces a Lagrangian label $a$ instead of the vertical ...
1
vote
0answers
40 views

Quantum mechanics not in $L_2$-space [duplicate]

As far as I understand the postulates of quantum mechanics use only properties of abstract Hilbert space. So could we use any other Hilbert space for calculations instead of $L_2$? What could it be? ...
-1
votes
1answer
7 views

Magnetic field size from electric field

An electric charge oscillates about the origin along the y axis. A distant observer is located at a point on the +z axis. You observe the wave from a given location and find that at a given ...
0
votes
0answers
14 views

Graphene plasmonics, Integro-differential eigenvalue equation

In my research around plasmonics in 2-Dimensional nanostructures like graphene, I encounter an eigenvalue integro-differential equation of the form: ...
-2
votes
2answers
77 views

Deriving the geodesic equation [closed]

I having been reading a general relativity book, but when in comes to the geodesic equation, it is not derived. How does one go about doing this?
0
votes
0answers
9 views

How can I tell apart the composition of my soft ferrites

I have an assorted bunch of soft ferrites. I need to know which ones are MnZn and which ones are NiZn, so I can sort them for usage at different frequencies.
-1
votes
1answer
24 views

Two bricks glued together

If we have two identically shaped bricks of different mass, and we glue them together, and then drop them without air resistance, they will not rotate. However, if we look at the torque experienced by ...
0
votes
1answer
17 views

Spinning Ball in Frictionless Tube

If we have a ball in a frictionless tube, and we begin to spin the tube about one end, the ball will exit the tube, correct? Indeed, there must be some centripetal acceleration, but then what force is ...
1
vote
1answer
19 views

How do we “cancel out” the torque from running?

Running certainly causes a torque on our body, as we are propelled forward via our feet; why doesn't this torque cause our bodies to spin about their center of mass?
0
votes
2answers
39 views

Derivation of $v=u+at$

I read the derivation of $v=u+at$ using integration. The steps are as follows - $$\frac{dv}{dt}=a dt$$ $$dv=adt$$ $$\int dv=\int a dt$$ $$\int dv=a\int dt$$ $$v=at+c$$ My questions are as follows - ...
19
votes
1answer
871 views

Local explanation of the Aharonov-Bohm effect in terms of force fields

Here is an interesting paper for the Physics SE community: On the role of potentials in the Aharonov-Bohm effect. Lev Vaidman. Phys. Rev. A 86 no. 4, 040101 (R) (2012). arXiv:1110.6169 ...

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