Particle Definition and 1000 Threads

Homework Statement Normalized equation for particle in a ring, where V=0 on a ring of radius 'a' and infinite everywhere else. Homework EquationsThe Attempt at a Solution Replcing x by rθ, $$-\frac{\hbar^2}{2I}\frac{\partial^2\psi}{\partial\theta^2}=E\psi$$ By guess, I found out that...

Hello, The particle Reynolds number makes me confused and I hope someone can help me on this please! Normally (as I read in every books and papers) that when a bubble or drop rises in a fluid, the bubble/drop Reynolds number is calculated by: Re = ρUD/μ where U is particle velocity, D can...

Homework Statement A smooth bead B is threaded on a light inextensible string. The ends of the string are attached to two fixed points A and C on the same horizontal level. The bead is held in equilibrium by horizontal force of magnitude 2N acting parallel to CA. The section of the string make...

Consider the case in which an incoming particle collides with stationary target particle producing new particles through the interaction. For example, $$e^{-}+e^{+}\rightarrow X+\bar{X}$$ My question is, why in general do the particles produced in such an interaction propagate outwards are...

Homework Statement A certain elementary particle lives only a time [T][/0] = 5 sec (proper time) before disintegrating. What velocity must the particle have if it is to reach the Earth from the Sun before disintegrating? Distance between the Earth and Sun is 1.5x10^11 meters.[/B]Homework...

Homework Statement the trajectory γ: ℝ→ℝ3 of a charged particle moving in a uniform magnetic field satisfies the differential equation γ''= B x γ'(t) . where B = (B1, B2, B3) is a constant 3-vector describing the magnetic field, and × denotes the vector product. (a) Show that the particle...

Particle accelerators use the electromagnetic field to accelerate charged particles. Would it be possible to build a particle accelerator for uncharged particles? Say we are given a narrow beam of neutrons. How could we accelerate them so that the accelerated particles were still in a...

Homework Statement A particle of mass ##m## moves along a circle of radius ##R##. The modulus of the average vector of the force acting on the particle over the distance equal to a quarter of the circle is: zero if the particle moves with uniform speed ##v##. ##\dfrac{\sqrt2mv^2}{\pi R}## if...

Homework Statement on a spherical astroid with a radius of 500km and an acceleration due to gravity of 3.0m/s2 How far from the surface will a particle go if it leaves the asteroid’s surface with a radial speed of 1000m/s? Homework Equations conservation of energy Ui + ki=Uf +kf U=-(GmM)/r...

Homework Statement Homework Equations x = (x1,x2,x3) are the coordinates of the current configuration and X = (X1,X2,X3) are the coordinates of the reference configuration where x = y(X,t) where y is a deformation of X. The Attempt at a Solution (a) taking the partial derivatives of xi with...

In the 1D particle in a box system why don't we take negative integer values of n besides the positive integer values? Well I thought about it and I think the reason is that during derivation we get ka=n (wavelength ) and thus n being negative implies that wavelength is negative hence contradiction.

I have been asked to determine the energy in MeV of an alpha particle and an Rn nucleus in the decay of Ra-226 using the conservation of energy and momentum. (assume Ra is at rest) Here is what i have done, I am just wondering if i did it properly. Thanks for your help :) Ek=kinetic energy...

I was reading the thread about wave particle duality linked from the newsletter, and I noticed it said (to use my own words) that the conflict between wave and particle dynamics can be avoided by using operator dynamics instead. Unfortunately, in the case of phonons, I've never seen a...

Can all seasoned physicists please confirm if it is true that wave particle duality is really wrong as when Bill stated in the decoherence branches thread "This is a little different than what you will find in a beginner text becauise it doesn't use the wave particle duality which is wrong - but...

Homework Statement A uniform cylindrical drum of mass M and radius a is free to rotate about its axis, which i is horizontal. An elastic cable of negligible mass and length l is wrapped around the drum and carries on its free end a mass m. The cable has elastic potential energy \tfrac12...

Homework Statement Imagine a particle with charge +Q moving with constant horizontal velocity passing perpendicular to electric field between two parallel plates. The length of the plates is L. Therefore, is the time spent in the field (well, between the plates), simply the length/horizontal...

Homework Statement If the 4.4-kg block is suspended from the pulley B and the sag of the cord is d = 0.15 m, determine the force in cord ABC. Neglect the size of the pulley. (Figure 1) Express your answer to three significant figures and include the appropriate units.Homework EquationsThe...

Homework Statement A one-dimensional stream of particles of mass ##m## with density ##\lambda## particles per unit length, moving with speed ##v##, reflects back from a surface, leaving with a different speed ##v'##, as shown. Find the force on the surface Homework EquationsThe Attempt at a...

Homework Statement Show that the largest possible change in the kinetic energy , ##\Delta E_{kin}##, of a particle of mass ##m## running into another particle of mass ##M## at rest in the lab coordinate system is \Delta E_{kin} = \frac{-4AE_{kin}}{(1+A)^{2}}, where ##A = \frac{M}{m}##...

Homework Statement For the particle in a box given in the above question, what is the probability of finding the electron between (i) x = 0.49 and 0.51, (ii) x = 0 and 0.020 and (ii) x=0.24 and 0.26 ( x in nm) for both n=1 and n=2. Rationalize your answers. Homework Equations...

some years ago it was big news when some aerogel bulk launched at the tail of a comet and bits of the comet dust got stuck in the gel. this was going to be recovered somehow and analysed. I do not know any more about that particular experiment but it died out of the mainstream news. anyone...

We've learned Q&M in modern physics but I need to make sure I'm getting this concept right... So the photoelectric effect demonstrated the fact that a photon (wave) can knock an electron out of a metal, which could only happen if a photon was a particle. So much for photons being waves. I get...

Consider a charged particle moving with velocity v, having the energy 1/2 m v^2. Now we deccelerate the particle very quickly; so quickly that the radiated energy is greater than the kinetic energy (it can be arbitrarily large). Note also that energy obtained from decceleration is positive...

Hello PF's members I know a magnetic field doesn't work on charged particles if magnetic field being perpendicular to the velocity of the particles. also i know magnetic field doesn't work if a charged particle enters with right angle into the field. But suppose that a charged particle like...

Homework Statement A photon beam is incident on a proton target (at rest). Particle X (and nothing else) with rest mass M=1.232GeV/c2 is then produced. Use m_p =0.938GeV/c2 as the proton mass. a) What is the energy of the photon beam, in terms of GeV? b) What is the momentum of the moving...

Homework Statement A particle moves with simple harmonic motion in a straight line with amplitude 0.05 m and period 12 s. Find: (a) the maximum speed, (b) the maximum acceleration, of the particle. Write down the values of the constants P and Q in the equation x / m = P sin [Q (t / s)] which...

Hi guys! I'm doing a research about teaching elementary particles in the middle school, something that isn't the reality in my country. Despite of the research in Physics Teaching be a lot advanced, the proposals made by them are not applied in the practice of the teachers. I want to propose...

Homework Statement A cannon that is capable of firing a shell at speed V_0 is mounted on a vertical tower of height h that overlooks a level plain below. (a) Show that the elevation angle \alpha at which the cannon must be set to achieve maximum range is given by the expression...

Homework Statement Homework Equations Formulas for a_r and a_theta. The Attempt at a Solution I got the second derative of r but I think the fluxie v is a mistake. I am sure that \dot{v} =a\ , right?

Say a particle was measured to be at a point C. Immediately after this, if i make another measurement, its given in griffith's book that the particle will still be found at C. Isn't this only possible if the particle was at rest?

Homework Statement A particle is attached by means of a light inextensible string to a point 0.4 m above a smooth horizontal table. The particle moves on the table in a circle of radius 0.3 m with angular velocity ω. Find the reaction on the particle in terms of ω. Hence find the maximum...

Homework Statement A particle is projected with speed v at an angle α to the horizontal. Find the speed of the particle when it is at a height h. Answer: √v2 - 2gh 2. The attempt at a solution a. Since PE gained is KE lost we need to find KE and PE. KE = 0.5 * m * (v sin α)2 (the vertical...

Homework Statement Two particles 1 and 2, each carrying 6.0 nC of charge, are located along an x axis, one particle atx=−30 mm and the other at x = 30 mm. Where along the y-axis is a particle 3 carrying a charge of +2.0 nC if it experiences an electric force of 6.9 × 10^−5 N ȷ^? Homework...

Homework Statement The wave function is given as Ψ(x,t) = Ae^[i(k1x-ω1t)] + Ae^[i(k2x-ω2t)]. Show that particle average velocity Vav = ħ(k1+k2)/2m equals ω2-ω1/k2-k1. Average momentum of the particle is Pav = ħ(k2+k1)/2. Homework Equations p = ħk E=ħω K = 1/2 * mV^2 The Attempt at a Solution...

So sorry to post what seems to be a well worn question. So the 4 forces of nature work by "particle exchange" ? Yes we understand the maths of "Fields" and we have the elegance of Maxwell and Newton/Einstein and these mathematical descriptions lead us to force exchange particles which can...

Hi everybody, I was reading about the free particle in a textbook and I got confused by the line: "If we adopt the convention that k and k are real, then the only oscillating exponentials are the eigenfuntions with positive energy" [Also see the attached picture with the...

Homework Statement Unstable particles cannot live very long. Their mean life time t is defined by N(t) = N0e−t/τ , i.e., after a time of t, the number of particles left is N0/e. (For muons, τ=2.2µs.) Due to time dilation and length contraction, unstable particles can still travel far if their...

Homework Statement Unstable particles cannot live very long. Their mean life time t is defined by N(t) = N0e−t/τ , i.e., after a time of t, the number of particles left is N0/e. (For muons, τ=2.2µs.) Due to time dilation and length contraction, unstable particles can still travel far if their...

Homework Statement An electron and another particle experience an attractive force of 0.0096 N when they are 0.001m apart. what is the charge of the other particle q1= -1.602E-19 F=-0.0096 r=0.001 2. Relevant equation how do you find q2 out to solve the equation The Attempt at a Solution

We were going over the basics of the photoelectric effect today in my solid state chemistry class when my instructor gave us a question asking what the wavelength of an ejected electron was. We worked through the question and got the answer, but that got me thinking. If the wavelength is...

What about the attached as a means of propulsion? It would be a spacecraft with a long magnet in the front. Attached on one side by boons the magnet would have a reflector/deflector or shield of some type e.g. aluminum. In interstellar space there would be charged cosmic particles moving in...

Homework Statement Problem given in the image attached. Uniform Magnetic Field : B Positive Charge : q Uniform Velocity : v Mass : m Charged particle enters the magnetic field making an angle θ with the plane perpendicular to the magnetic field. Width of the region of Magnetic field : d d <...

Hi folks, I number of years ago, I asked a question about real particles interacting with virtual particles - since then, I've learned a little bit (maybe not too much :-), but I'm still curious about one thing. Original thread here...

Homework Statement A particle moves with constant velocity along the curve r = e^(θ) and z = r (cylindrical coordinates). The speed, v, is constant. a) Calculate the velocity and acceleration of the particle in terms of θ and v. b) Show that the velocity and acceleration are perpendicular...

Homework Statement Homework EquationsThe Attempt at a Solution If I consider a coordinate system with the -Y axis along the direction of force and X axis along a line perpendicular to it (except the direction of velocity vector) then this problem is equivalent to the usual projectile motion...

We know that matter and anti matter annihilate each other if they come together. Then what would happen in a collision of a anti particle with our body?

Homework Statement what will be Lagrange,s equation of motion for a particle confined to move on surface of sphere whose radius is expanding such that Homework Equations Euler-lagranges equation of motion d/dt(∂L/∂{dq/dt})-∂L/∂q=0 The Attempt at a Solution Z=(R+R0e^at)cosθ...

Maybe my question is a bit more philosophical than scientific. In the macroscopic world entropy means that things become more chaotic and less orderly as they decay. It seems to me somewhat paradoxical that in the quantum world lower generation particles "decay" into the first generation...

As I understand it (e.g. from discussions around the Fermi field theory of the nuclear force), a spin 1/2 particle can emit a spin-1 particle and simultaneously flip its spin (say, spin +1/2 -> photon +1 & spin -1/2); but how does this work with spin-2 particles? Does it need to emit pairs in...

Homework Statement Find the speed of a particle whose total energy is twice its rest energy. Homework Equations E2 = p2c2 +m2c4 The Attempt at a Solution 4m2c4 = p2c2 +m2c4 3m2c4 = p2c2 SQRT(3)mc2 = pc SQRT(3)mc = p SQRT(3)mc = mv SQRT(3)c = v I know I can use E = gamma*mc2 to get the...