0
votes
1answer
6 views

Am I just some energy traveled at light speed?

I don't quite understand E=mc² very well, and here is my question: does this equation mean masses are just condensed energy? And does this mean that the extra energy an object has when traveling at ...
5
votes
5answers
344 views
+200

Can you deduce absolute motion through magnetism?

Trying to understand magnetism I stumble into this example: Suppose there are two electrons travelling side by side in deep space (say, between Mars and Jupiter) at 1 cm distance at .99 c. In this ...
0
votes
1answer
10 views

Can pressure be subtracted from pressure gradient

I just want to know if the pressure can be subtracted from pressure gradient. I did a google search and it didn't help me. I know the question is silly and the answer to it should be no but at one ...
0
votes
0answers
2 views

Feynman Diagram of $\nu_\mu + p \rightarrow \nu_\mu + p + \pi^0$

According to my class notes, the following interaction is possible $$\nu_\mu + p \rightarrow \nu_\mu + p + \pi^0$$ I tried drawing a Feynman diagram and got the below, but don't know what happens ...
2
votes
3answers
47 views

How electromagnetic waves carry energy?

Its said that electromagnetic waves carry energy. Is this because these waves are made up of electric and magnetic field which can cause changes to the stuff that falls with in their range ? That is ...
0
votes
1answer
21 views

Einsteins theory of relativity and formula of kinetic energy

After seeing both Einsteins theory of relativity [E=mc2] and the formula of kinetic energy [K.E=mv2] I noticed that that they are mostly the same, with the only difference that Einsteins theory uses a ...
0
votes
1answer
17 views

The true dimension of Dirac field

In natural units with $\hbar=1$ and $c=1$, as we know, the energy dimension of the Dirac field $\psi(x)$ in QED is $\frac{3}{2}$. But in cgs units, what is the true dimension of the Dirac field ...
0
votes
0answers
3 views

Springs and Cantilevers - how linear and repeatable are they under deformation?

I know you guys only deal with the ideal, but in practice how linear and repeatable is the response of a spring or cantilever when deformed under a test mass?
0
votes
2answers
446 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
7 views

Why do we use a vector space for gluons?

One gluon state cannot be added to another since qcd heavily violates superposition. Why do we still use vector spaces to describe them?
0
votes
0answers
5 views

why is it so successful to start of with a pair potential before quantizing

As soon as we use the quantum theory all orders of correlation functions start to appear if we move from one scale to another. Why was it so successful to start of with a simple pair potential in the ...
1
vote
2answers
187 views

Why quantum computer is so fast factoring numbers?

I am trying to get myself a more clear understanding of the root of significant acceleration in number factoring by P. Shor's algorithm. I am probably missing something but q-bits for me are no more ...
2
votes
1answer
45 views

Diffraction wavelength relationship

This question appears somewhat similar to other questions asking about why wavelength affects diffraction (a concept which I'm still not 100% sure on...) however my query is different and not answered ...
1
vote
2answers
20 views

Photon absorption in a medium - basic principle?

I am trying to understand the basic physics of photon absorption in a medium. Take the example of oxygenated hemoglobin (red curve). Clearly at different frequencies/energies relatively more or less ...
3
votes
3answers
264 views

Difference between $E$ field configuration, sheet of charge: infinite sheet of charge, conducting vs. non-conducting

This is a very easy question, but I often confused myself. Perhaps someone could explain this concept again: A non-conducting infinite sheet of charge has the electric field configuration ...
3
votes
3answers
63 views

Field equations of a given action

Provided an action: $$S[A_\nu] = \int\left(\frac{1}{4\mu_0}(A_{\gamma,\mu}-A_{\mu,\gamma})(A_{\zeta,\alpha}-A_{\alpha,\zeta})\eta^{\gamma\zeta}\eta^{\mu\alpha}+\frac{1}{2}\nu^2A_\mu A_\gamma -\beta ...
0
votes
0answers
11 views

What is the difference and/or similarity between multiple universes in inflation and in quantumphysics?

Some theories propose that there are more universes. In one of them it is said that there are parallel universes, due to inflations after the big bang that created them. But in the two-slit ...
0
votes
1answer
49 views

Understanding work with rotational momentum/moment of inertia

Apologies for the basic question but between the vectors and the spinning, I'm getting confused. If I have a wheel with moment of inertia $I$ spinning at some rate $\vec\omega$ around an axis, what ...
0
votes
1answer
24 views

Steady state RLC circuit analysis

In an RLC series circuit let applied EMF be given $V=V_0\sin\omega t$, $$Z=Z_C+Z_R+Z_L=R+i\left(\frac{1}{\omega C}-\omega L\right)$$ $$|Z|=\sqrt{R^2+\left(\frac{1}{\omega C}-\omega L\right)^2}$$ Then ...
0
votes
0answers
6 views

Conversion from PPBV to PPBM

What is the conversion between PPBV and PPBM (parts per billion by volume to parts per billion-meter)? Can I simply integrate a curve of PPBV to get PPBM?
5
votes
4answers
403 views

What will be final velocity of three charges $q$, $q$, $2q$? [closed]

What will be final velocity of three charges q, q and 2q kept along an equilateral triangle of side r at infinite distance. All three masses are equal. I tried to conserve Total Energy ...
-2
votes
1answer
18 views

Is drift velocity related to diameter of conductor?

Please help me out of the confusion regarding relation of drift velocity of electrons with dimensions of conductor .
-1
votes
0answers
17 views

How much part of an iceberg sinks in water?

How much part of iceberg of water sinks in water. Well I know the answer is 92%, I want anyone to prove it for my homework. (water is not salty and is at 4 degree celsius)
0
votes
0answers
7 views

Ibm quantum computer references

Can someone point me towards technical discussions or papers on IBM's new quantum computer? Is it similar to the D-wave?
0
votes
0answers
3 views

How to calculate counting rate of two detectors in quantum eraser experiment?

How to calculate the counting rate between two detectors? In their paper this one , they use Glauber Formula. But I don't know this formula and can't find this formula online.
-2
votes
0answers
53 views

Electric potential inside a solid sphere [on hold]

We have charged solid sphere and have to find electric potential inside it. I tried it by two methods, By integrating $\int \vec{E}\cdot\text{d}\vec{r}$ for both outside and inside the sphere ( ...
0
votes
0answers
10 views

How to Find equations of motion and the Noether current for Lagrange symmetry group given the Lagrangian?

photo of the problem instead of writing it here just because I don't know how to write equations here, sorry.
1
vote
2answers
502 views

Range of poissons ratio

I know the range of poisson's ratio is -1 to 0.5 but how do you arrive at this expression? I am a 11th grade student and I am not too familiar with advanced physics
0
votes
1answer
11 views

Conductors, charges and method of images; Intuition?

Two charges e and -e are placed at distances d and 3d, respectively, above an infinite conducting plane (directly above one another). Find the force on the charge e. To Solve this I consider another ...
0
votes
1answer
206 views

Degrees of freedom in double Atwood machine?

Why the degree of freedom in double Atwood machine (one block on one side and a pulley with one block in its each side on other side) is 2 and not 1? According to the formula $s=3*n-m$; where ...
23
votes
4answers
990 views

Does topology have any role in classical physics?

I've seen many applications of topology in Quantum Mechanics (topological insulators, quantum Hall effects, TQFT, etc.) Does any of these phenomena have anything in common? Is there any intuitive ...
9
votes
4answers
144 views

How do we know the Schwarzschild solution contains an object of mass $M$?

The Schwarzschild metric is $$ds^2 = - \left( 1 - \frac{2GM}{r} \right) dt^2 + \left(1-\frac{2GM}{r}\right)^{-1} dr^2 + r^2 d\Omega^2.$$ In Carroll's GR book, it is claimed that $M$ is the mass of the ...
0
votes
0answers
25 views

Hamilton's equations of motion on Dirac's formalism

I'm having several doubts about the procedure proposed by the Dirac-Bergmann algorithm in order to get the correct equations of motion of electrodynamics (Maxwell's equations). Suppose I've already ...
0
votes
0answers
10 views

How do you calculate the change in location of the focal point by rotating the lense?

Image you have a lens with a certain focal length. Light will be focused into the focal plane on the Optical Axis if the light is a collimated beam which travels parallel to the Optical Axis. But I ...
0
votes
0answers
24 views

Velocity of (un)rolling toilet paper

Consider a roll of toilet paper. It consists of an inner cardboard core of radius $r_1 = 2cm$ wrapped in 5m of paper so the external radius is $r_2 = 3cm$. The paper is unrolled by holding on to the ...
1
vote
2answers
43 views

How to stop water flow in a siphon?

I have assembled a small DIY drip-irrigation system for my terrace garden. Please have a look at the attached image. I switch on a small pump to start the drip-irrigation system and then switch it ...
3
votes
2answers
310 views

Fiber optics with broadband, incoherent light

I wonder if someone could help clarify waveguiding with broadband, incoherent light please. If we take a telecomms fiber, which is single-moded above ~1.4 μm and couple a laser beam in, we assume ...
9
votes
2answers
742 views

Do stars remain electrically neutral? [duplicate]

How electrically neutral do stars remain through their lifetime? As an example, I could imagine processes such as coronal mass ejections leaving the Sun in a slightly charged state. Are there such ...
0
votes
1answer
614 views

How to calculate the ship resistance caused by water viscosity

If there is a ship going in the sea at 50km/h, and a length of 5m, width of 2m, how do I calculate the ship resistance caused by water viscosity? in other words I want to calculate the drag Force that ...
8
votes
4answers
5k views

Radius of curvature

I have come across a question that asked me to find the radius of curvature of a projectile. As far as I know, the path of a projectile is a parabola and I have found mention of the radius of ...
3
votes
1answer
52 views

Why doesn't the four-gluon vertex give mass to gluons?

We have a four-gluon vertex and a gluon vacuum condensate. Why doesn't this provide us with gluon masses, as in the NJL model where the condensate gives rise to an effective mass term?
0
votes
0answers
8 views

Difference between PIN photodiode and silicon surface barrier in beta spectography

In a physics undergraduate lab we performed an experiment in spectography of beta decay. We used two detectors to measure the energy spectrum of Bi207: PIN photodiode Silicon surface barrier ...
4
votes
2answers
159 views
+50

Condition for adiabatic approximation, derivation?

In quantum mechanics it is said that an adiabatic approximation is valid when $$T\gg \frac{\hbar}{\Delta E},$$ where $T$ is the time scale of variation of the Hamiltonian and $\Delta E$ is the typical ...
1
vote
0answers
32 views

Is the helicity of photon Lorentz invariant?

If the helicity of a photon is $+1$ in an inertial frame, then is the helicity of this photon $+1$ in another inertial frame? The helicity operator is $$ h=\mathbf{S}\cdot\hat{\mathbf{p}} $$ with $$ ...
0
votes
0answers
11 views

Transforming to a rotating frame in the x-basis

This is given as the equation obtained after transforming to the rotating frame in the x-basis. I know that the general form of the rotation operator for the spin system is given by: $$ D(\hat ...
0
votes
0answers
13 views

Calculate Temperature change in a solid due to inductance heating

Trying to calculate temperature increase in a solid due to a current flow, is this along the right lines? First I have calculated resistance due to resistivity, then calculated power from the given ...
1
vote
1answer
25 views

Gravitational collapse (conservation of energy)

During gravitational collapse, gravitational potential energy of the gas is converted to its internal kinetic energy so the internal energy of the clous of gas is said to be increased But isn't ...
0
votes
0answers
19 views

Water Moving Through Coffee Grinds

Like many of my peers, I rely on coffee as if it were prescribed to me. It might even be classified as an addiction if it weren't for the cultural norms surrounding a cup of coffee or tea in the ...
1
vote
0answers
13 views

Deriving Rabi oscillations using the Heisenberg picture of QM

The semiclassical treatment of an simple two level atom in a resonant electromagnetic field is usually done in the Schrodinger/Interaction picture of QM, by assuming that the wavefunction of the atom ...
5
votes
1answer
107 views

Flow through a rifled pipe

In turbulent flow the friction is inertial for the most part: the chaotic flow causes the fluid in the faster moving center to interchange randomly with the fluid near the edge. This eventually allows ...

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