Particles Definition and 1000 Threads

Homework Statement Consider Newton’s force law for two particles interact through a central force F12(r1',r2',u1,u2), where by Newton’s third law F12 = -F21. m1(d^2r1/dt^2) = F12(r1,r2,u1,u2) m2(d^2r2/dt^2) = F21(r1,r2,u1,u2) A. Show that Newtonian mechanics is form invariant with respect...

hello! what is the most efficient way to produce charged particles? like protons (H+) or electrons or ions or anything like that thanks!

Homework Statement Consider particles in a gas centrifuge. This device is used to separate gases of different molar mass by rotating a cylinder at high rates. Derive two equations: one for the pressure (P) and one for the particle number density (nv) as functions of M, r, w and T, where r is...

So our professor showed us wave patterns on a vibrating plate, by sprinkling powder over it. I'm curious as to why it behaved as it did.The powder moved to nodes, but I'm not sure why. I think it just gets bounced around until it lands on a node, which is stationary, so it then stays there. Is...

Homework Statement : Block B has acceleration of 4 m/s2... Relative acceleration of block A w/ respect to B is 4 m/s2. Find magnitude & direction of accel for A?[/B] Homework Equations a_A = a_B + a_A/B[/B]The Attempt at a Solution a_A = 4 +4 = 8 m/s2 <-- 8*cos(20) = 7.52 (x-component)...

1. Problem: Consider the composed system of two particles of spin ##s=1## where their angular momenta is ##l=0##. What values can the total spin take if they identical? What changes when they are distinguishable? The Attempt at a Solution : The problem I have here is incorporating the fact...

The below is what has me confused. It's essentially stating that if we apply a force on a positive charge and push it close to a negative charge, our applied work is negative. Why is this? I am confused about it because W = Fd and both F and d have the same direction. The potential energy U...

What is the evidence for dark matter being new particles as opposed to some modified form of gravity?

It looks to me like all the massless particles so far discovered may be force bearing particles, there being 3 of them. Am I right? If so can it be said that forces propagate at the speed of light whilst what we might think of a tangible particles cannot? I did post this question on another...

Homework Statement Two particles with spin ##S_1=1## and ##S_2=1## are in our system. For wavefunction of the first particle we know that ##S_{1z}|\psi _1>=\hbar |\psi _1>## while for the second particle ##S_{2x}|\psi _2>=\hbar |\psi _2>##. a) Find wavefunction ##|\psi _1>## in basis with...

1. In griffiths the following is written down in the chapter of identical particles: ##\Psi(\vec{r_{1}},\vec{r_{2}})=\pm \Psi(\vec{r_{2}},\vec{r_{2}})## Where it's + for bosons and - for fermions. However in class we have seen that for two electrons in the spin singlet situation the POSITION...

A thought experiment that is a consequense of a question someone asked in my particle physics class: We place an isolated electron. We wait 10 years, and place a half ring of electrons (spaced far apart from each other, but uniform) 10 LY away from our central e. Will our charges move? If so...

what is the correct understanding of a virtual particle? the popular science books would have us believe that a virtual particle magically pops up out of the woodwork, steals some energy and then puts it back before it ( the particl) disappears. Like a thieving employee who steal $100 out of the...

Hi All, I am in need to calculate the ultrasound (20MHz) absorption of particles (polystyrene of size 15 microns) in water. I tried to search in the internet, but couldn't find any simple analytical expressions. Can someone please help me ! Thanks in advance! Regards, Radel...

So if I somehow constructed a Freeze Ray that could lower someone's or something's temperature to absolute zero, would they split into subatomic particles ?

I really want to understand the answer to this question. Q: What is an exchange particle? A: A virtual particle that let's force act between particles in an interaction. This answer was given in my A-Level textbook but I can't for the life of me decode what it means. For example in beta minus...

Since an electron generated a negative charge around itself and can push other electrons around itself, waves can travel through electrons. These are electromagnetic waves. But quantum theory proposes that the pushes between electrons happen in discrete packets. Electromagnetic packets called...

I've heard of the muons and electrons that constantly hit Earth's surface in cosmic rays coming from extra terrestrial particles that break up in Earth's atmosphere but I was curious what factors played a role in the type of radiation produced from these particles in the atmosphere (i.e. More...

I've recently taken to understanding capacitors and capacitance. If I understand them correctly they are what store electrical charge or electrical energy. I don't quite understand their purpose though, do they keep the breadboards from overloading with power but keeping little pockets of...

I was reading a lot that "Virtual particles are just math..." and many physicists for some reason get angry explaining it. But I suspect this point of view is interpretation-biased and is outdated for 3 reasons listed below: 1. The (mathematical) discovery of Quantum Decoherence had provided a...

(I assume that the three section headings below form the template referred to below) 1. Homework Statement n identical equi-distant particles are distributed equi-distantly around the circumference of a ring of radius r in space. Each particles is of mass m, so the total mass of the ring is...

Homework Statement In a given inertial frame two particles are shot out simultaneously from a given point with equal speeds u at an angle of 60 degrees with respect to each other. Using the concept of 4-velocity or otherwise, show that the relative speed of the particles is given by ##u_R =...

from what i understand they pop into and out of existence because + 1 - 1 = 0 and because quantum mechanics... and that's the same reason we have matter in the first place, right? because we had anti matter and matter (from virtual particles, right?) in the beginning of the observable...

1 what are the various methods/ways, besides quantum entanglement, to put, some of, the photon properties an indeterminate state? 2 what are the various methods/ways, besides polarizers or measurement, to put the photon properties a determinate state?

Why recent particle physicists don’t consider models of particles (quarks, leptons) built from more light subparticles? Is there problems of principle or the available experimental data don’t need similar models?

How does a person charge a particle? Like a neutron, for instance?

For those of you who have read the theorem, probably have also read Matt Leifer's review of it. In his review he says that the only way to remain psi epistemic is to be an anti realist(copenhagen), or to abandon the bell frame work. Is it viable to be psi epistemic but still believe that...

I read about an experiment, showing how present or future can affect the past, instead of details will simply share the link. http://physicsworld.com/cws/article/news/2012/aug/03/can-the-future-affect-the-past Is there any study (I wasn't able to find with some research) about how a particle...

How can be sure than the unique stable particles are the neutrons, the electrons, the photons and the neutrinos? Couln´t it be possible than at low energies were there more particles??

Homework Statement Two identical spin-1/2 particles of mass m moving in one dimension have the Hamiltonian $$H=\frac{p_1^2}{2m} + \frac{p_2^2}{2m} + \frac{\lambda}{m}\delta(\mathbf r_1-\mathbf r_2)\mathbf s_1\cdot\mathbf s_2,$$ where (pi, ri, si) are the momentum, position, and spin operators...

Could somebody take a stab at explaining how can quantum fluctuations give neutral elementary particles a magnetic moment? (in the usual explanation given by QFT textbooks, I think there are people around here denying the existence of quantum fluctuations, insert the more neutral expression...

Homework Statement Consider two spin 1/2 particles. Initially these two particles are in a spin singlet state. If a measurement shows that particle 1 is in the eigenstate of ##S_x = -\hbar/2##, what is the probability that particle 2 in this same measurement is in the eigenstate of ##S_z =...

Homework Statement Two radioactive isotopes of singly charged plutonium(Pu-249 and Pu-244) are accelerated through a potential difference of 3.00kW and enter a uniform magnetic field of 1.50T directed perpendicular to their velocities. By performing relevat calculations, show that the ratio of...

Let's say there's a question where there are two charges placed, and a point in between and above the line connecting the two charges forms a triangle like this: http://session.masteringphysics.com/problemAsset/1413940/2/p19.5.jpg What would one have to do in order to find the electric field...

Homework Statement Particles of charge q and 3q are placed 90m away from each other. A third particle is place in between them and the total electric force on this particle is zero. Determine the position of this particle. Homework Equations F(E)=(k)(q1)(q2)/(r^2) The Attempt at a Solution...

Do particles popping in and out of existence due to quantum vacuum fluctuations create a gravitational effect? My thought is yes If so, considering all the quantum particles in existence at one time at a given moment in the universe, added to the mass of the universe as well as the mass of...

I have notions of the mathematics involving (entangled state is one which is not a product state of two qubits, etc) the idea of entanglement. However, still can not figure out how to, let us say, pick a particle (which type of particle we can use as qubit? protons? electrons? ununumbiums??) A...

1.Problem: An electron with energy ##E## which is much higher than its restmass collides with a much much heavier particle "A" of mass ##m## which is at rest. Find the maximal transfer of four-momentum. (Elastic collision)2. Conservation of four momentum3. Everything in natural units. So I go...

How we can know that there are no more particles that graviton and standard model particles??

I have been reading on wikipedia that dark matter is made up of a not yet characterised type of sub atomic particle. Now we know that particle energies and relative positions cannot be known with precision by Heisenberg principle but we can calculate quantities like the drift velocity of charges...

Are there any particles on the Standard Model of Particle Physics with all the properties of a WIMP particle(Weakly Interacting Massive Particles)?

Hi Guys, I just want to put this out there. If a particle changes it's behaviour based on wether it's been observed or not what is the dividing factor? What is actually happening? Is it simply the fact that a conscious mind is watching it and because of that the particle changes its behaviour to...

[Note by mentor: This thread does not use the homework template because it was moved here from a non-homework forum.] Hello, I have a problem with this exercise. I don't know if my solution is right! Could you check it, please? A proton with kinetic energy Kp is moving in a uniform magnetic...

Homework Statement Would stirring a fluid separate the particles? Homework EquationsThe Attempt at a Solution You stir tea to integrate the tea and the sugar so I would say that stirring would not separate the particles. Any help? Thanks!

Hi All, The S-matrix is defined as the inner product of the in- and out-states, as in Eq. (3.2.1) in Weinberg's QFT vol 1: S_{βα}=(Ψ−β,Ψ+α) \Psi_{±α} are the eigenstates of the full Hamiltonian with a non-zero interaction term. Can \alpha describes a neutron ? Since it is not stable, it is...

Homework Statement Two particles, each of mass m, are attached one to each end of a diameter PQ of a uniform circular disk, of mass 4m, radius a with its centre at O. The system is free to rotate about a horizontal axis through A, a point on PQ such that OA = b as indicated in the diagram...

Link to article My knowledge of physics past basic mechanics is weak but as I understand the Standard Model these two new particles are combinations of other elementary particles rather than two new ones. Anyone want to expand on this article? Big news, not so big? :) Here is some discussion...

As an object moves, it is contracted in the direction of it's motion. Why wouldn't each individual subatomic particle be contracted rather than the object as a whole?

Homework Statement Two particles oscillate in simple harmonic motion with amplitude A, about the centre of a common straight line of length 2A. Each particle has a period of 3.3 s, and their phase constants differ by π/9 rad. (Assume the lagging particle starts at +A. Also assume that the...

If there is such a thing as a virtual particle, is there also such a thing as a virtual wave? what would that actually mean?