Particle Definition and 1000 Threads

The 4-momentum of a massless particle traveling in the z direction is (k, 0, 0, k). What is the significance of the value of k? It does not determine the speed since they always travel at light speed. If one particle has momentum (k, 0, 0, k) and another has (j, 0, 0, j) with j not equal to...

I'm reading up on the Lagrangian equation, but what I'm asking is to do with electromagnetism. In the first equation here: http://www.phys.ufl.edu/~pjh/teaching/phy4605/notes/chargelagrangiannotes.pdf L equals the kinetic minus the potential energy. For the potential energy term, I just don't...

Hi! I want to start solving problems from the text 'Orbital Mechanics for Engineering students' by Curtis 2nd edition. Is this the right place to post? Homework Statement 2.1 Two particles of identical mass m are acted on only by the gravitational force of one upon the other. If the distance d...

wich creates an electric field charge or a charged particle (electron)

Hi all, I recently learned the concept of Maxwell's speed distribution and became interested in how to use similar momentum distributions to study the probabilistic motion of a classical free particle. I have done some of my own reading on probabilities and distributions (no formal lessons yet)...

I am about to teach some of an introductory course for bachelor students in the field of medical physics. More specifically the topic "Photon and charged particle interactions with matter" in respect to radiation therapy (again, medical physics). I know there are a lot of topics within radiation...

Hello, Analogous to mass of fundamental (not composite) particles coming from interaction of those particles with the Higg's Field, does charge of fundamental particles come from interaction of those particles with some known/hypothesized fundamental field? Thank you!

Hello everyone and happy new year. I have a quick dilemma on the concept of entanglement for a two-particle system and I am looking for some clarity: Say we have particle ##A## and particle ##B##. Both particles can be in either of the two states that we call ##|\Phi>## and ## |\beta>## or in...

Homework Statement First sorry for the traduction mistakes. Prove that any wave function of a particle in a 1 dimensional infinite double well of width a, returns to its original state in time T=4ma2/(πħ) . Homework Equations Ψ(x,t)=∑cnψn(x)·exp(-i·Ent/(ħ)) En=n2π2ħ2/(2ma2) The Attempt at a...

We consider a monoatomic gas in a closed box. A textbook says : Since the assumption is that the particles move in random directions, the average value of velocity squared along each direction must be same. Why the assumption is that the particles move in random directions implies that the...

Do they need a nuclear engineer in a Synchrotron ? if yes what kind of job does he do ?

Homework Statement Homework EquationsThe Attempt at a Solution ## E \propto n^2 ## ## \frac { \Delta E} E = \frac { 2n +1} {n^2} ## In the limit of large quantum number, ## \frac { \Delta E} E = \frac { 2} {n} ##, option (a).

Homework Statement Homework EquationsThe Attempt at a Solution The energy eigen - value of a particle in a box is given by ## E_n = \frac { n^2 h^2}{8mL^2} ## . Now, applying classical mechanics , ## \frac { p^2}{2m} = \frac { n^2 h^2}{8mL^2} ## . ## p \propto \frac { 1} L ## , So...

Homework Statement A particle of mass m is moving in a circular path of constant radius r such that its centripetal acceleration a varies with time t as a = k2rt2, where k is a constant. Show that the power delivered to the particle by the forces acting on it is mk4r2t5/3. [/B] I have solved...

Homework Statement The electric field in an xy plane produced by a positively chatged particle is 7.2(4x+3y)N/C at the point (3, 3)cm and 100x N/C at the poiint (2, 0)cm. Note, x and y used here are unit vectors. find the x and y co-ordinate of the charged particle what is the charge of the...

Hi everyone. Just a small, quick question I have: Can negative ions be accelerated by a Van de Graaff particle accelerator? My initial reaction is no, because the terminal (the sphere with the charges allocated on the outside) is positive, which means negative ions would be attracted and not...

If a micro-particle tunnel through a barrier which has higher potential energy than the energy of the particle, then from where does the particle get the energy to cross that barrier?

I was reading this thread by stevendaryl https://www.physicsforums.com/threads/second-quantization-vs-many-particle-qm.835472/ I have two questions 1. which QFT picture are those, Schrodinger, path integral or Heisenberg. 2.In QM the creation/annihilation operators raise and lower energies...

Homework Statement A particle is restrained to move in 1D between two rigid walls localized in ##x=0## and ##x=a##. For ##t=0##, it’s described by: $$\psi(x,0) = \left[\cos^{2}\left(\frac{\pi}{a}x\right)-\cos\left(\frac{\pi}{a}x\right)\right]\sin\left(\frac{\pi}{a}x\right)+B $$ , determine...

Hi guys, I am having an issue with what my lecture is saying in these slides, I have attched my slides below. Here is my issue. I am very confused by the ##E<\Delta ## Beacuse I can't see how this has any momentum as it would produce an imagery number. And ye say that ##E<\Delta ## cannot...

I shall try to expose my question as briefly and clearly as possible. Within a very old and classical approach (Newton), discussions take place in a three-dimensional Euclidean space and the concept of force is represented by a vector which is proportional to the mass of the object at hand (m...

Point Particle in Relativity and Electrodynamics: “The Classical Theory of Fields” – by Landau and Lifshitz, in its discussion about classical size of a particle, concludes that:- Thus we come to the conclusion that in classical (non-quantum) ‘relativistic mechanics’, we cannot ascribe finite...

Me and my friend have recently (half a year ago) had a huge debate, between ourselves, about the wave-particle duality. We took sides in light being a particle or a wave. I was for particle he was for waves. At the end of a hot-filled week of arguing, the debate ended up with the acceptance of...

Can anyone shed a bit of light on what a Higgs Boson is, how it was discovered and what its discovery implies for physics ?

A non ionized neutral gas should still emit thermal radiation.,say xenon. Is this solely because of electron transitions ? I ask this because a lot of sources attribute the emission to charge particle acceleration,so neutral atoms should not do this,is this right?

Homework Statement Two parallel plates located at a distance "L" from each other they maintain a potential difference "V" because of a battery (as shown in the picture). Through a small hole, made in bottom plate, electrons get into system (with mass "m" and charge "-e"), with velocity "v" and...

Homework Statement The detector is made of two co-planar layers of silicon two metres apart, and there is a plane of wire chambers halfway between them. The wire chamber can measure a track with precision ##100\mu##m. What is the highest momentum a particle can have for which the detector will...

Homework Statement A proton beam is going from north to south and an electron beam is going from south to north, so in which direction is the electron beam deflected Homework EquationsThe Attempt at a Solution . [/B] I thought an electron...

Homework Statement Hi, i have this problem: In a 3D space, a free particle is described by : $$ \Psi = Ne^{-ar} $$ with $$ r=| \vec r | $$ at the time t=0 . How can we write the wave function whit $$ \hbar \vec k $$ ?Homework EquationsThe Attempt at a Solution I know how to resolve this...

$$\tiny{243.13.01.18}$$ $\textsf{The following equations each describe the motion of a particle.}\\$ $\textsf{For which path is the particle's velocity vector always orthogonal to its acceleration vector?}$ $\begin{align*} \displaystyle (1) r(t)&=t^8i+t^5j\\ (2) r(t)&=\cos(8t)i+\sin(2t)j\\ (3)...

Hello, Orbital mechanics is a bit of mystery to me. Let us have a particle with mass m orbiting the Sun (with mass M)in a circular orbit with radius R. The velocity vector V is always tangential to the orbit. Let us also have a weak, constant ("drag") force Fd that is always pointing in the...

We often use SO(N) and SU(N) to describe symmetries in particle physics. I am not clear which one to choose when I try to discuss a symmetry. For example, why do we use SU(3) but not SO(3) to describe the symmetry of the three colors of quarks? Similarly, why do we use SU(2) but not SO(2) to...

Homework Statement The following question involves a torque acting on a particle in rotational motion. It provides practice with the various equations for angular velocity, torque etc A particle of mass ##m## initially has position...

In which fields of physics can we apply machine learning concepts? If I take data science master's with minor in particle physics or astrophysics, what are the possibilities that I would be employed as a physics related data scientist? (I am a programmer and I would like to change my career...

In Quantum Field Theory, I am led to believe that there is a different field for each type of particle. When particles interact, it is an exchange of vibration between the fields. What mechanism is at play when one field influences another in this way? It seems I've only ever found...

Homework Statement Homework EquationsThe Attempt at a Solution Since the force is always directed towards C , angular momentum about C should be conserved . But that doesn't seem to help as we need the relation at any general angle . How should I proceed ?

Hello. Could anyone please help me understand particle spins? I read the 'A Brief History of Time' and now would like to understand them better. Basically from zero. Any resources? I have had a look at Wikipedia, but the language is not clear and there is too much information. Thank you.

In general, is it of more interest to consider multi particle states consisting of fermions & bosons or multi particle states consisting of only fermions (or only bosons)? I have seen that if it's of the latter type, then the study becomes in certain way more easy to carry on, though the former...

Hi, This a Classical Mechanics problem I've been trying to solve for a few days now. I cannot use Lagrangian or Hamiltonian formulation, it must be solved using classical Newtonian formulation. One must determine the equations of movement of the particle in cartesian, spherical and cylindrical...

The gravitational field of some massive body appears one way to a nearby stationary particle. But does the field appear to be distorted to a particle traveling at relativistic speeds?

Homework Statement A particle moving in a periodic potential has one-dimensional dynamics according to a Hamiltonian ## \hat H = \hat p_x^2/2m+V_0(1-cos(\hat x))## a) Express ## \frac{d <\hat x>}{dt}## in terms of ##<\hat p_x>##. b) Express ## \frac{d <\hat p_x>}{dt}## in terms of ##<sin(\hat...

I am looking for a way to make a small particle accelerator for really cheap. I am in 8th grade and do not know a lot or have a lot of money but still want a project. if you have a pdf or other doc of plans that would be much appreciated thanks.

Homework Statement Suppose a heavy particle (mass m1) has an elastic head-on collision with a very light particle of mass m2 initially at rest. Show that if m1>>m2, the velocity of the projectile (m1) is practically unchanged, whereas the target particle (m2) acquires a velocity v2' = 2v1...

Hello. I solve this problem: 1. Homework Statement The particles of mass m moves without friction on the inner wall of the axially symmetric vessel with the equation of the rotational paraboloid: where b>0. a) The particle moves along the circular trajectory at a height of z = z(0)...

Homework Statement Homework EquationsThe Attempt at a Solution Velocity of particle at any time t is v = vxi + vyj Net Force on the particle F = (2qvyB)i + (2qvxB)j Net acceleration of the particle = F/m Magnitude of net acceleration = (2qvB)/m Particle has an initial velocity as well...

Homework Statement Consider a spherical particle immersed in water. It will experience random collisions with the surrounding water molecules. Suppose there are such water molecules around the particle. Half (n/2) of the water molecules will push the particle to the right and the other half to...

Homework Statement Many experiments in physics call for a beam of charged particles. The stability and “optics” of charged-particle beams are influenced by the electric and magnetic forces that the individual charged particles in the beam exert on one another. Consider a beam of positively...

Homework Statement Homework Equations The right hand curl rule gave me the counterclockwise direction for the magnetic field but I am confused about how is it going to work for the particle. Thanks The Attempt at a Solution

Homework Statement The reaction dd → απ0 (where α is the Helium-4 nucleus and d denotes the deuteron) has never been observed. Why? Homework EquationsThe Attempt at a Solution [/B] So I checked first the masses to make sure energy/momentum are conserved and found out that mass of 2d is...

Homework Statement The current limit on the proton’s lifetime is determined by observing a large body of water for a long time and noticing that no one of the hydrogen nuclei in H2O have decayed. Assuming that the experiment making this measurement has been going on for 10 years, how many tons...