Particle Definition and 1000 Threads

Homework Statement A particle of mass M and 4-moment P decays into two particles of masses m1 and m2 1) Find the total energy of each particle (lab frame). 2) Show that the kinetic energy T1 of the first particle in the same reference frame is given by $$T_1= \Delta M (1 - \frac{m_1}{M} -...

Homework Statement Hello PF, I need some help with the assignment given: v=18-2t^2 m/s, where t is in second. When t= 0 the position of the particle is s_0 = - 3 m. For the first 5 seconds. Determine the total distance ( i got it to 65,33 ft) and the net displacement Δs, and the value of s at...

Homework Statement I want to plot a graph of the survival probability of the initial state ψ = e-|x| for a free particle. Hopefully this will enable me to plot some more difficult examples like the inverted oscillator etc for a project but I'm struggling fundamentally with the free particle...

Homework Statement Good day all! Quick question: As part of a problem statement, I'm asked to verify if the trajectory: \frac{dx}{dt}=\frac{cgt}{\sqrt{1+g^2t^2}} Is "consistent". Homework Equations None The Attempt at a Solution Im not sure what "consistent" means. Does it mean, \frac...

I am hoping and I would most appreciate that one or more PF participants will be able to help me find out the following, either by posting answers or citing useful references. 1. What types of particles are candidates for being DM stuff? 2. For any of these candidates, are there estimates of...

Homework Statement At our university we were given this problem: charged ball with mass of ##m = 0.0001 kg## and charge ##Q = -10^{-5} C## is placed on geometric axis of thin torus with inner radius of ##r_{inner} = 0.05 m##, outer radius of ##r_{outer} = 0.1 m## and surface charge density...

Is "a light, particle or wave" an absolute question or a relative question? Should a light be considered as a particle or as a wave depends upon the relative size of the system? When considering a visible light relative to a basket ball should it be considered as particle, while a visible light...

[Mentor's note: Split off from another thread because it's a different question] I have a question about the single-photon double-slit experiment's results that isn't about the role of consciousness. Should I go ahead and ask it here or ask it elsewhere? (Briefly: If the results are lots of...

How fast does the fastest subatomic particle travel at? When left at a temperature or zero degress Celsius.

I was watching a lecture and there was a connection drawn between classical rotational energy and quantum rotational excitation. The energy of a rotating system is $$E = (L^2) / 2 I $$ with L being the angular momentum and I the moment of Inertia. Then to make it quantum$$ n^2 * ħ^2$$ was...

Hello! Can someone please recommend me a particle physics book that starts from the very basic concepts, but gives complete proofs for everything (for example, I want to start with the "spinless" particles interactions as an introduction to Feynman calculus, but I don't want them to just write...

Hi, I am learning quantum entanglement. I am interested to create an up to date list of all known : - Photon Quantum States - Particle Quantum States - Classically entagled photon states I guess that there is an organization out there that already have this info. If someone can point me into...

Hi, I'm trying to understand the derivation to an equation I found in the following paper: http://pubs.acs.org/doi/abs/10.1021/nn203035x I posted almost this exact question on Physics Stack Exchange but got no replies so I decided to try it here instead, I hope that's ok...

Hello, Let's assume we put a small iron particle in a magnetic field. What is the equation of the route that the particle performs? Is it the minimal route length that is possible? (the magnet is a stick-form)

Homework Statement This is new for me, so forgive me my clumsiness. I am working on the following problem: A particle p is moving with a velocity v1 = c (speed of light) towards an object q, which is moving in the same direction with the speed v2, where v1>v2. Now, v2 is a function of the...

Hello Everyone, For the particle in the 1D box of width ##L##, the time invariant Schrodinger equation is cast in the form of the Hamiltonian operator and automatically leads to the energy eigenfunctions $$\Psi(x) = \sqrt{\frac 2L} sin(n\pi x/L)$$ I know that these energy eigenfunctions...

In the Standard Model, for any particle, I have only found properties related to electromagnetic and gravitational (in fact mass does not necessarily mean it is a property related to gravity, but to emergy)forces like charge and mass. Why there isn't anything about the other two interactions...

Can someone help me understand how the following two actions are related? S_1 = \int \left(-\dfrac{1}{2}mg_{\mu\nu}\dot{x}^\mu\dot{x}^\nu - U\right) d\tau S_2 = \int \left(-m\sqrt{g_{\mu\nu}\dot{x}^\mu\dot{x}^\nu} - U\right) d\tau Both of them lead to the correct geodesic equation as the...

Homework Statement I'm given that the energy of a particle in a rectangular box is the following: E =\frac{\hbar \pi^2}{2m}(\frac{n_x^2}{L_x^2}+\frac{n_y^2}{L_y^2}+\frac{n_z^2}{L_z^2}) I'm to show that if the length of the box is increased adiabatically and quasistatically from L_x to 8L_x...

Homework Statement Earlier my teacher put this equation on the board, π_0 --> γ+γ It appears to work until you consider spin. Homework Equations a quick google search reveals that the spin of a photon is +1 and the spin of a pi meson is 0 The Attempt at a Solution This appears to work for...

I would be very grateful for help with deriving the following equation... "A smooth fixed plane is inclined at 30 degrees to the horizontal. A wedge of mass M and angle 30 degrees is held on the surface so that its upper face is horizontal, and a particle of mass m rests on this face. The...

Using the Lagrangian : L = ½mv^2 - qφ + qAv What is the physical intuition of Av ? I know that A is the magnetic vector potential and that v is the velocity of the charged particle. I just don't know what their dot product means physically .

If you consider the one-dimensional case of a particle constrained to move on the edge of a circumference, the energy spectrum is continuous and two times degenerate. Why the fact that the particle can move in clockwise and counterclockwise implies that the spectrum is degenerate twice? In any...

Does a charged particle need to experience a momentum changing force to emit light? Or is it sufficient for an observer to accelerate relative to the particle?

Homework Statement Use the eigenfunction Ψ(x) =A'eikx + B'e-ikx rather than Ψ(x)=Asinkx + Bcoskx to apply the boundary conditions for the particle in a box. A. How do the boundary conditions restrict the acceptable choices for A’ and B’ and for k? B. Do these two functions give different...

So we know for a fact that an electron is a particle. The "wave" like properties are not waves at all, its just the wavefunction that is a mathematical wave which is used for getting probabilities for where the electron will end up. But what about a photon? When a charge oscillates, its gives...

Hello. We are elementary school kids who built a cloud chamber for our science project to test out the effectiveness of different shields against background radiation. We are not sure about something involving beta-particles. Can you help us please? We know low-energy beta particles cannot...

Homework Statement Hi guys. Just wondering if anyone could help me with Q7 part a) on the pdf I have attached below. I think my working are not correct but I can't see other way. If I add 6. and 7. together I would get an ans in terms of what the question is asking but I am not sure if that is...

When a bubble in the ocean bursts water drops are thrown into the air. How fast do these water drops dry out creating solid salt particles? There must be a formula for calculating this and I am guessing that the following variables must figure in the formula: - Droplet size - Salt concentration...

Hello everyone, I am working on a project in astrophysics in which I need to include now some type of particle distribution (as a function of the radius). I was wondering if there is some accepted function that would describe the number of particles per radius in astrophysics. Saturn's rings...

Homework Statement In a two-particle collision the square of the invariant mass is. M is total mass of the system (M2 is the square of the total mass) m is the mass of each particles E is the energy of each particles p is momentum vector of eache particles Homework Equations M2 = (E1+E2)2 -...

Hello. I'm actually taking Ph.D. course for plasma physics and I think I'll finish this course within this year. I took classes in quantum field theory and general relativity in last semester luckily and experience of these subject ignited a desire to study theoretical particle physics and...

Homework Statement An alpha-particle with velocity 3.5 x 106 strikes a block of gold, atomic number 79 and mass number 197. Find the distance of the closest possible approach between the alpha particle and a gold nucelus, assuming Coulomb's law holds over such distances. Assume mp = mn = 1.67 x...

Homework Statement Suppose that a particle follows the path r(t) = 2cos(t)i + 2sin(t)j Give an equation (in the form of a formula involving x and y set equal to 0 ) whose whose solutions consist of the path of the particle. Homework Equations None that come to mind The Attempt at a Solution I...

I'm currently in year 12 (studying IB with hl physics, maths and chemistry) in the UK and am starting to look at uni courses. For a few years now I have been absolutely fascinated by the particle physics/quantum side of physics. At the movement I would love to work in research in this sort of...

Hello there, I have always loved physics and wanted to get a degree in physics, particularly particle physics. But my father told me that if i have a physics degree i won't be able to get a job easily so i should pick an engineering course instead. i looked through engineering types but i...

What is the basic concept which decides the spin of a particle. Like, electron has a spin of +- 1/2... What do this 1/2 signifies. Other spins are also there like 1 and 2. What do they signify? Is there any possibility of any particle with spin other than 1/2, 1 or 2?

Is the reflection of a (massive) quantum particle from a mirrored surface considered a Lorentz Boost?? If it is non-collinear ?

What are the main maths used in the mentioned fields of physics? Not just general terms like "Calculus" but more specific maths. Also, what is the logic behind using these to solve problems in physics? Example, why would someone use differential calculus to calculate the probability of a...

Hello. Suppose you dissolve something in water. I know that the boiling point should increase because as the water boils the solute's entropy decreases, and the net entropy should increase. Now suppose, that I dissolve GI chlorides in the water. Each solution of the salt has the concentration...

Hypothetically, could we have a mass-less electrically charged particle of spin 1/2 confined by a hypothetical potential so that at large distance scales the particle looked like localized massive charged particle of spin 1/2? I'm thinking of a mass-less charged particle that does some kind of...

Homework Statement Basically having a problem when trying to theoretically calculate the mass of alpha particle in a charged field. r is the unknown radius of curvature m = mass of an alpha particle (6.646 *10^-27 kg) v = velocity of an alpha particle immediatly after decay (1.381 *10^7 m/s)...

Homework Statement A particle has speed u‘ in the S’ frame, its track making an angle ## \theta’ ## with the x’ axis. The particle is viewed by an observer in frame S, the two frames having a relative speed parameter ## \beta ##. (a) Show that the angle ## \theta ## made by the track of the...

Homework Statement All in the pic below. Part of the solution presented. Didn't present the whole thing as that would clutter the page. I just want to know how they set up the x coordinate for the particle. Homework Equations This problem is just about using the lagragian. So my issue is...

Homework Statement [/B] A particle of rest mass ##m_0## is is caused to move along a line in such a way that its postion is $$x = \sqrt{b^2 + c^2 t^2} -b$$What force must be applied to the particle to produce this motion? 2. Homework Equations The velocity of the particle as seen from...

Hi all, Some time ago I was reading about Anderson localization (posted a question about it was well) - this got me thinking about vacuum fluctuations. I think I have the wrong idea in my mind - so wanted to ask the great community here about it: Quantum (vacuum) fluctuations must have an...

Mostly used for weapons, can sources of directed energy be contained at low intensities? In theory, could it be set to specific wavelengths, frequencies, intensities or whatever to say remove particles of lower cohesiveness from other surfaces or materials?

I am trying to figure out what winfield oh physics i should study for a career. I absolutely love learning about strange quantum phenomena but also love learning about extremely small particles and how they interact at the smallest of scales Would i be interested in a career in particle physics...

Hi guys! I'm struggling with the following problem: Consider two distinguishable (not interacting) particles in a quadratic 2 dimensional potential well. So ## V(x,y)=\left\{\begin{matrix} 0,\quad\quad-\frac { L }{ 2 } \le \quad x\quad \le \quad \frac { L }{ 2 } \quad and\quad -\frac { L }{...

It's been a while. But I have always received the help I needed on this forum. I had this question in my head, When a particle accelerates, it creates an oscillating electric field, and a photon. How much does this effect, affect the energy of the particle itself? Say I had a particle...