Particle Definition and 1000 Threads

In this article, researchers have used electrons to image light as both particle and wave at the same time. https://phys.org/news/2015-03-particle.html

I have a problem finding ##\left|Ψ(x,t)\right|^2## from the following equation: $$Ψ(x,t) = \frac 1 {\pi \sqrt{2a}} \int_{-∞}^{+∞} \frac {\sin(ka)} k e^{i(kx - \frac {ħk^2} {2m} t)} dk$$ and tried to plot like the pic below (Source Introduction to quantum mechanics by David. J. Griffiths, 2nd...

Hi, I'm trying to simulate the process of charged particles attenuation in matter (like this) by a montecarlo-metropolis algorithm in Python. I thought that I could use for the number of particles at thickness ##x## the formula ## N (x) = N_0 e^{-\mu x} ##, so the probability in this case will...

Homework Statement A particle is moving parallel to x-axis in the positive direction with velocity v such that at all the instants the y -axis component of its position vector is constant and is equal to 'b'. Find angular velocity about origin. Homework EquationsThe Attempt at a Solution I...

What causes an elementary particle to "decay" into other elementary particles? And where do these particles come from if they were not part of the original particle?

Hello! I am a current undergraduate physics student with a keen interest in primarily astronomy and particle physics. Keen to help out some with some basic homework questions and read more about people's experiences in the field of physics!

Homework Statement The longer-range inter-nucleon force is not a direct result of the gluon field, but is indirectly affected by a quark-antiquark pair (i.e. meson). If this ‘residual’ strong interaction between nucleons is mediated by a π-meson, then what is the maximum time period in which...

Homework Statement (I) An experiment to determine ceramic particle sizes showed that the rate of descent when suspended in a fluid ranged from 1.2 × 10–6 m s–1 to 5 × 10–6 m s–1. 
The density of the material was 3800 kg m–3 and the density and viscosity of the fluid at room temperature were...

Hi to all, I have a random number generator in FORTRAN, which gives a random numbers to my particles initial velocity in three dimension (vx,vy,vz). If, I want to make my particles to embark to move with a specific weight (eg. Maxwellian), what should I do? absv = sqrt(vx*vx+vy*vy+vz*vz) wt=...

Homework Statement I've just read that light can behave like a wave at times, and a particle at other times. How does the light from the Sun traveling towards Earth behave? A wave? A particle? Or both? And is it in any sense something that actually starts at the Sun, travels across space and...

I have seen that the more a particle has a high energy, i.e ##E##, the more its lifetime is short, respecting so the uncertainty principle. But by the definition of this uncertainty principle : ##E\,\Delta t \geq \dfrac{\hbar}{2}##, I can write : ##\Delta t \geq \dfrac{\hbar}{2E}##, then...

Is the kinetic energy of a particle quantized? Does it increase and decrease in discreet amounts?

I've got a question and can't find any answer on google. So the centripetal force for a particle in uniform circular motion is mv^2/r. This also means that if F > mv^2/r than the particle will get closer to the center and if F < mv^2/r than it will travel further from the center. Say a 5 kg...

I’m having a hard time, as I begin learning QM, knowing what it applies to, if I can put it that way. Is QM the rules that describe how the particles of the Standard Model interact with each other? Or what is the best way to understand the relationship between what one studies when one studies...

What happens to the velocity? Say we have a piece of space debris in free fall. It has a particular velocity at a given time. Then say at some later time it's bombarded with ionic gas or something that causes it to become charged. Does the velocity change? My guess would be yes, because the...

Hi, I was reading about magnetic reconnection in astrophysical plasma and it says that magnetic reconnection transforms magnetic energy into heat via ohmic dissipation, particle acceleration and kinetic energy. It is not clear to me the difference between particle acceleration and kinetic...

Consider the following reaction of strong interaction (in a scattering process) $$n+\pi^+\to \Lambda_0+K^+\tag{1}$$ Then the particle ##\Lambda_0## formed decays with weak interaction $$\Lambda_0\to \pi^+ +p\tag{2}$$ For each decay process I measure the four momenta of ##K^+##, ##\pi^+##...

In particle phyisics four-momentum is used and De Broglie relation is used to understand what lenghts can be "seen" in an experiment. Here (page 6) https://people.phys.ethz.ch/~pheno/PPP/PPP2.pdf it is claimed Where ##Q^2## is not actually "momentum" but its the square of the four momentum...

The deuterium exists only with the proton and neutron of aligned spin, which suggests that the residual strong force is greated with aligned spins, i.e. the binding energy is greater if the spins are aligned. On the other hand the mass of ##\Delta^{+}## is greater than the mass of proton ##p##...

I've seen somwhere a claim that Hamilton-Jacobi euqation is the only formulation of classical mechanics which can treat motion of particle as wave motion. There was something about hamilton prinicpal function, hamilton characteristic function and one of these change in time like wavefront or...

When particles are shot at the plate/screen in the double slit experiment, why doesn't the particles interact with the screen? Shouldn't the plate act as an observer and "collapse" the wave function into one or the other slit? Why does it take a measuring apparatus to know which slit the...

Let's suppose I have a potential well: $$ V(x)= \begin{cases} \infty,\quad x<0\\ -V_0,\quad 0<x<R\\ \frac{\hbar^2g^2}{2mx^2},\quad x\geq R \end{cases} $$ If ##E=\frac{\hbar^2k^2}{2m}## and ##g>>1##, how can I calculate how much time a particle of mass ##m## and energy ##E## will stay inside...

I1. Homework Statement A cylindrical vessel whose diameter and height both are equal to 30 cm is placed on a horizontal surface and a small particle p is placed in it at a distance of 5 cm from the centre. An eye is placed at a position such that the edge of the bottom is in the plane of...

Homework Statement Statement of the problem (quoting from my assignment): a) write equations of motion b) try to solve analytically Given: m1, m2 - two masses R - distance between two masses Homework Equations V=-G(m1/r + m2/(R-r)) F=-dV/dr The Attempt at a Solution a) Equations of motion: v...

I am reading Griffiths' Introduction to Quantum Mechanics, specifically the chapter on scattering. He is discussing the scenario where an incoming beam of particles scatter off an azimuthally symmetric target. At large separation ##r## from the scattering centre, the wavefunction for incoming...

A photon acts like a wave and a particle. In the double slit experiment the photon seemingly interferes with itself which is troublesome to me. To help better understand this, I would rather think of the photon as a particle and the wave as something that is independent of the photon where the...

< Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown >[/color] Question: An experiment is proposed to directly measure the width (Γ) and mass (m_H) of the Higgs boson via the reaction: muon+ + muon- > H. Sketch a graph of the expected cross section...

A particle of mass m in xy plane is attracted toward the origin with the force $$\begin{align}\vec{f} = - \frac{k^{2} m}{r^{6}}\vec{r}\end{align}$$ where ##\vec r## is position vector of particle measured from origin. If it starts at position ##(a,0)## with speed $$v=\frac{k}{\sqrt{2} a^{2}}$$...

Homework Statement I have a mother particle at rest, which decays to a daughter particle. The daughter has mass m, momentum p and energy E and is at an angle θ1. Now I have to assume that the daughter is emitted at an angle θ2, and the mother is moving along the x-axis with velocity βc. I need...

Hello physics forums. I'm trying to solve an old exam question. Would love your help. Homework Statement A free particle in one dimension is described by: ## H = \frac{p^2}{2m} = \frac{\hbar}{2m}\frac{\partial^2}{\partial x^2}## at ##t = 0## The wavefunction is described by: ## \Psi(x,0) =...

Just for my knowledge, not to confuse the OP, why would you say, for example, the double slit experiment does not show both of these properties in one measurement method? [Mentors' more: this thread was forked off from another thread]

Homework Statement A particle moves in the x-y plane relative to a fixed point O. Initially, the particle is at the point 6i-2j, where I and J are position vectors in the directions of the x and y-axis respectively. The particle moves such that t seconds after the start of its moition, the...

Homework Statement A particle with mass m is moving on the x-axis and is described by ## \psi_b = \sqrt{b} \cdot e^{-b |x|}## Find the probability distribution for the particles momentum Homework Equations ## \Phi (p)= \frac{1}{\sqrt{2 \pi}} \int_{-\infty}^\infty \Psi(x,0) \cdot e^{-ipx} dx##...

The following from Wiki re Hawking Radiation:“... vacuum fluctuations cause a particle–antiparticle pair to appear close to the event horizon of a black hole. One of the pair falls into the black hole while the other escapes. In order to preserve total energy, the particle that fell into the...

Before quantum mechanics, light was generally seen as a wave and matter as particles (biliards). From e.g. the discovery of the photoelectric effect, one saw that light can also be seen as a particle. From e.g. the double slit experiment, one makes the interpretation that matter can also be seen...

Homework Statement The velocity of a particle at a certain point is given as \vec v=5(y\hat i - x\hat j). How to find the general equation of the path of the particle? Homework Equations Here, \frac{d\vec x}{dt}=5(y\hat i - x\hat j). The Attempt at a Solution As the velocity is not given as a...

Suppose we have a particle of mass ##m## moving freely in the xy-plane, except for being constrained by hard walls to have ##-L/2 < y < L/2##. Now, the energy eigenstates would be something like ##\psi (x,y) = C \psi_x (x) \psi_y (y) = C e^{-ikx}\cos\left(\frac{n\pi y}{L}\right) ##, where...

Homework Statement Homework Equations Emec - PE = KE The Attempt at a Solution When particle starts at x = 4 KE = .5(.25)(225) = 28.125 Energy of system = 28.125 I don't have anything with position here so i am unsure how to find what position that the energy will be equal to the Emec and...

1. At the instant of the figure, a 6.70 kg particle P has a position vector of magnitude 4.30 m and angle θ1 = 43.0° and a velocity vector of magnitude 3.40 m/s and angle θ2 = 32.0°. Force , of magnitude 7.40 N and angle θ3 = 32.0° acts on P. All three vectors lie in the xy plane. About the...

So there's a free particle with mass m. \begin{equation} \psi(x,0) = e^{ip_ox/\hbar}\cdot\begin{cases} x^2 & 0 \leq x < 1,\\ -x^2 + 4x -2 & 1 \leq x < 3,\\ x^2 -8x +16 & 3 \leq x \leq 4, \\ 0 & \text{otherwise}. \end{cases} \end{equation} What does each part of the piecewise represent...

Homework Statement [/B] A particle P1 moves with a constant velocity v along x-axis, starting from origin. Another particle P2 chases particle P1 with constant speed v, starting from the point (0, d). Both motion begin simultaneously. Find - 1. Initial acceleration of P2. 2. Ultimate...

Hi there, my name is Leon and I am a physics undergraduate. Recently I decided to dig into the field of particle physics by getting some related books. I definitely will get some books on quantum field theory (Peskin, Scrednick, mandl and shaw...etc), since qft is a framework of particle...

Homework Statement Homework Equations F = k(q1q1/r^2) K = (mv^2)/2 The Attempt at a Solution I got number 18 easy enough, number 19 seems simple but I'm not getting the right answer. I'm calculating Force exerted by each charge on the new charge using F = k(q1q1/r^2) for the three charges...

Could a particle near a black hole about to enter rid the string of its vibration?

Homework Statement During the ##\alpha## decay of ##^{238}_{92}U## an ##\alpha## particle is fromed inside the nucleus. Given that the last 4 nucleons in ##^{238}_{92}U## have an average binding energy per nucleon of ##6.1MeV##, estimate the kinetic energy of the ##\alpha## particle when it is...

A subatomic particle can either be a wave or a particle. When it is a particle, what actually is it? is it literally like a tiny physical ball rattling around? (If not, then what is it?) And when it is a wave, what is it? From my understanding, when a particle behaves like a wave, the...

Homework Statement A particle moves along a circle in a region of uniform magnetic field of magnitude B=4.0 mT. The particle is either a proton or an electron. It experiences a magnetic force of magnitude 3.2x1015 N. What are (a) the charge of the particle? (b) The particle speed? (c) The...

Homework Statement Show that it is impossible for an ultra-relativistic particle with ##pc>>Mc^2## to disintegrate into two identical massive particles of mass m. Homework Equations Conservation of four momentum The Attempt at a Solution The four momentum of the ultra-relativistic particle...

Suppose a neutral meson decays into an electron and a positron. Are the two particles entangled as they fly apart? Before any measurement takes place, are the particles in a mixed superposition as to which one is the electron, and which one is the positron? Is there a way to test for such...

Is it possible there is a particle desert where there are no new particles between the weak and Planck scale yet there is new physics before the Planck scale.. can you give examples how this can occur? An example. If we can distinguish quantum interpretations.. won't this be new physics that...