1d Definition and 417 Threads

Hi! I have a question related to boundary condition in a one dimensional beam subject to compression and traction efforts. In my class notes I have the following: If we consider a 1D beam of length L which is fixed at x=0 and subject to an effort F at x=0 we have the following boundary...

Homework Statement Consider a particle which is confined in a one-dimensional box of size L, so that the position space wave function ψ(x) has to vanish at x = 0 and x = L. The energy operator is H = p2/2m + V (x), where the potential is V (x) = 0 for 0 < x < L, and V (x) = ∞ otherwise. Find...

Hi everyone, I need a little help understanding how periodic reciprocal space applies to the Debye model for solids. Many thanks in advance! If we start with the general derivation of a dispersion relation for a 1D system, with atoms coupled by springs, one gets the following relation $$\omega...

I have a working Matlab code solving the 1D convection-diffusion equation to model sensible stratified storage tank by use of Crank-Nicolson scheme (without εeff in the below equation). As indicated by Zurigat et al; there is an additional mixing effect having a hyperbolic decaying form...

So, velocity is a vector, right? And vectors can't have negative magnitudes, right? Then why is leftward velocity considered negative in 1D kinematics? It just seems off to me. Same with acceleration, and pretty much _every vector in all of physics._

I wish to numerically compute solutions of the 1D heat equation using the Crank-Nicholson scheme: The equation is: \partial_{t}u=\partial^{2}_{x}u I use the discretisation: u_{i+1,j}-u_{i,j}=s(u_{i+1,j+1}-2u_{i+1,j}+u_{i+1,j-1})+s(u_{i+1,j+1}-2u_{i+1,j}+u_{i+1,j-1}) Where s=\delta...

Hey everyone, I’m trying to simulate a 1D Shallow Water wave in FORTRAN using the Lax Wendroff Method. The case is fairly simple. I have a wave generator on one end of a water pool and a wall boundary on another. The waves start traveling towards the wall and are ‘reflected off’ the wall. The...

hello dear physicists I will work in my thesis on 1D materials using DFT as a numerical method to find the properietes of these 1D materials I would be very happy if someone can help me with references (books, links, articles, vedios ...) that could help me to advance in my work Thank you

Homework Statement Consider a one-dimensional metal wire with one free electron per atom and an atomic spacing of ##d##. Calculate the Fermi temperature. Homework Equations Energy of a particle in a box of length ##L##: ##E_n = \frac{\pi^2 \hbar^2}{2 m L^2} n^2## 1D density of states...

When you curl 1 dimensional thing like a line.. won't it become 2D? I'm trying to imagine how a compactified dimension in superstring theory actually look like in our world. Let's take our 3D world and say the depth got compactifed or curl up to Planck length or a millimeter. What kind of...

Homework Statement 1D Potential V(x) = mw^2x^2/2, part of a harmonic oscillator. Suppose that the spring can only be stretched, so that the potential becomes V=infinity for x<0. What are the energy levels of this system? Homework EquationsThe Attempt at a Solution I argued my way though this...

Homework Statement 1D atomic chain with one atom in the primitive cell and the lattice constant a. The system in described within the tight binding model and contains N-->∞ primitive cells indexed by the integer n. The electronic Hamiltonian is $$H_{0} = \sum_{n} (|n \rangle E_{at} \langle n |...

Homework Statement Derive the differential momentum equation: dp=-\rho udu. Homework Equations \oint_{ CS}^{ } \rho \vec{U}(\vec{U}\cdot \vec{n})dA=-\oint_{ CS}^{ } p\vec{n}dA for steady state flow... The Attempt at a Solution I tried to solve it like in the attached picture, but can someone...

I am trying to write code for analytical solution of 1D heat conduction equation in semi-infinite rod. The analytical solution is given by Carslaw and Jaeger 1959 (p305) as $$ h(x,t) = \Delta H .erfc( \frac{x}{2 \sqrt[]{vt} } ) $$ where x is distance, v is diffusivity (material property) and t...

The solution of 1D diffusion equation on a half line (semi infinite) can be found with the help of Fourier Cosine Transform. Equation 3 is the https://ibb.co/ctF8Fw figure is the solution of 1D diffusion equation (eq:1). I want to write a code for this equation in MATLAB/Python but I don't...

Dear all, I am trying to find the capacitance of a parallel plate structure that comprises a spatially varying (linear) dielectric in one dimension. I have two methods of solving this which give different answers, and I am not sure which is correct. I consider the dielectric region to be...

Homework Statement Solve ##\Delta\phi = -q\delta(x)## on ##\mathbb{R}##. Correct answer: ##\phi = -\frac{q}{2}|x| + Ax + B## Homework EquationsThe Attempt at a Solution In one dimension the equation becomes ##\frac{d^2 \phi}{d x^2} = -q\delta(x)##. We integrate from ##-\infty## to ##x## to...

Stupid question: I have the following pipe configuration: Working fluid = ambient air Pipe1 = 6 inch ID x 24 inch length Expansion1 = 2 inch length Pipe2 = 8 inch ID x 2 inch length Fan1 = assume 200 CFM @ 2860 rpm, 0.05 inH2O Contraction1 = 2 inch length Pipe3 = 6 inch ID x 12 inch length...

I am trying to diagonalize hubbard model in real and K-space for spinless fermions. Hubbard model in real space is given as: H=-t\sum_{<i,j>}(c_i^\dagger c_j+h.c.)+U\sum (n_i n_j) I solved this Hamiltonian using MATLAB. It was quite simple. t and U are hopping and interaction potentials. c...

(I list this as Advanced because the question is not what it seems from the title.) So most know the cases: no damping, underdamping, critical damping, overdamping. I got that: this is not a request for explanation. Rather... Does anyone know of a web page that has some tutorial ANIMATION...

Consider the conceptual model presented in the attached image, of heat conduction in a bar. There is a heat source at left side and heat is observed at point Ho after a distance L from the source. If we consider only heat transfer through conduction then this problem can be modeled by...

Homework Statement An Airbus 380 needs to reach the velocity of 280 kmh^-1 before it takes off. The maximum acceleration the plain reaches in the runway is 0.95 ms^-2. Verify THAT the plane can use an airport with this runways. Runway 1: 3805 meters (SSW-NNE) Runway 2: 2400 meters (S-N)...

Hello! I'm trying to simulate a one dimensional time independent BEC, I hope this is the right place to ask for help. First of all, here's my code in Python. import sys import numpy as np import matplotlib.pyplot as plt if len(sys.argv) == 1: niter = 100 elif len(sys.argv) == 2: niter...

I'm having some trouble finding consistent results for the derivation of the 1D phonon density of state. I'm applying periodic boundary conditions to a 1D monatomic chain. I can work through and find that D(K)=L/(2π). This is the same result as given by Myers (1990, p. 127). Myers uses only...

Hi All I would like to know if there is a way to produce simple one dimensional kinematic exercises with space-time metric tensor different from the Euclidean metric. Examples, if possible, are welcome. Best wishes, DaTario

\bf{Setup} Hi! I am trying to derive the wavefunctions of the zero energy solutions of the Schrodinger equation in a 1D p-wave superconductor (Kitaev model). I am starting with the Hamiltonian $$ \begin{equation} H = \left[\begin{array}{cc} \epsilon_k & \Delta^{\ast}_k\\ \Delta_k & -\epsilon_k...

okay so i need some help interpreting some of the results, so (-ħ2/2m)Ψ''=E-V0Ψ; So i set k2= 2m*(E-V0)/ħ2 and so : Ψ''=-k2Ψ so if V0=0 or is smaller than E, k2 is positive; *need for help starts here* Ψ=Aeikx+Be-ikx; another result for this would also be only eikx so is the second term only...

Homework Statement The wave function of a particle of mass m confined in an infinite one-dimensional square well of width L = 0.23 nm, is: ψ(x) = (2/L)1/2 sin(3πx/L) for 0 < x < L ψ(x) = 0 everywhere else. The energy of the particle in this state is E = 63.974 eV. 1) What is the rest energy...

Homework Statement At t < 0 we have an unperturbed infinite square well. At 0 < t < T, a small perturbation is added to the potential: V(x) + V'(x), where V'(x) is the perturbation. At t > T, the perturbation is removed. Suppose the system is initially in the tenth excited state if the...

Homework Statement Hello- I'm having trouble understanding a problem: Consider a sealed 1D pipe of length L. At t=0, v=0 everywhere and the pressure is given by: P=P_0 +δP and δP = (p-bar)x/L P_0 and (p-bar) are both constants. and I'm supposed to find density (ϱ) as a function of x and t...

Hi. I'm taking a look at some lectures by Charles Kane, and he uses this simple model of polyacetylene (1D chain of atoms with alternating bonds which give alternating hopping amplitudes) [view attached image]. There are two types of polyacetylene topologically inequivalent. They both give the...

Homework Statement I'm currently working on a homework set for my intermediate QM class and for some reason I keep drawing a blank as to what to do on the first problem. I'm given three potentials, V(x), the first is of the form {A+Bexp(-Cx^2)}, the others I'll leave out. I'm asked to draw the...

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.

Homework Statement A particle of mass m moves along the x–axis under the influence of force ##F_x=-ax+bx^3## , where a and b are known positive constants. (a) Find, and sketch, the particle's potential energy, taking U(0) = 0 (b) Identify and classify all equilibrium points (c) Find the...

Homework Statement [/B] This is a computing coursework problem. (There is a reasonably long theory preamble). Create a single slit centred on the origin (the centre of your array) width 10 and height 1. The array containing the imaginary parts will be zero and the array containing the real...

Hello! So if I want to describe dΨ(x)/dt can I use 1D wave equation?

Wikipedia says this: "the dimension of a mathematical space (or object) is informally defined as the minimum number of coordinates needed to specify any point within it." Say that there is 1D space "contained" within 2D space and the former can be represented as a line in a 2D Cartesian...

Hello! Maybe someone will be able to suggest something about the following quite simple problem: 1D problem on axis "X". Particle moves only along "X" axis and starts its motion from X=0. However, when "X<0" particle disappears. Particle is influenced by some kind of force in such way that we...

Was the beginning of the univeres's Big Bang, a one dimensional construct which then formed into a two dimensional form and later, our three dimensions with time?

Homework Statement Hi all, attempting to make a Method of Characteristics solver in Matlab. I'm particularly hoping that there are some computational nuclear engineering guys about who might have a bit of experience programming a simple version of one of these. I'm trying to create the solver...

Homework Statement Car A is traveling a distance d behind Car B. Initically both cars are traveling at the same speed of 60 ft/s. Suddenly Car B applies the brakes, causing Car B to decelerate at 8ft/s2. It takes the driver of Car A 0.75 seconds to react, and when she applies her brakes Car A...

Homework Statement Problem: Consider a "crystal" consisting of two nuclei and two electrons arranged like this: q1 q2 q1 q2 with a distance d betweem each. (q1=e, q2=-e) a) Find the potential energy as a function of d. b) Assuming the electrons to be restricted to a one-dimensional...

Disclaimer: This is a homework problem I need to analytically solve the diffusion equation for a 1d 1 group slab with width a, and source distribution Se^(-k(x+a/2)) I've gone through the math, and come up with my homogeneous and particular solution and attempted to apply the boundary...

Hello, As I understand there is a problem in physics where point-like massive (or charged, etc.) particles would have infinite mass/energy (or charge, etc.) density. I'm curious how in the context of String Theory how we address the same problem? I have come to understand Strings as...

Just like it says, are all solutions of the 1D time independent Schrodinger equation, by default, energy eigenstates? I'm having a hard time imagining how solutions, with these conditions, that aren't energy eigenstates could exist if they have to satisfy the relation E \psi(x)=\hat{H}\psi(x)

For a 1D QHO we are given have function for ##t=0## and we are asked for expectation and variance of P at some time t. ##|\psi>=(1/\sqrt 2)(|n>+|n+1>)## Where n is an integer So my idea was to use Dirac operators ##\hat a## and ##\hat a^\dagger## and so I get the following solution ##<\hat...

Hi everyone, I need help for preparing a Hamiltonian matrix. What will be the elements of the hamiltonian matrix of the following Schrodinger equation (for two electrons in a 1D infinite well): -\frac{ħ^{2}}{2m}(\frac{d^{2}ψ(x_1,x_2)}{dx_1^{2}}+\frac{d^{2}ψ(x_1,x_2)}{dx_2^{2}}) +...

Homework Statement In outer space, a ball with mass 0.25kg and charge +4/K C is shot from 5m towards a +0.5C charged ball with an initial velocity of 20 m/s What main Physics principle should be used to solve this problem? What is the closest the small ball will get to the large one? What is...

Homework Statement There's a particle moving in a 1D potential V(x) with mass m. The particle's normalised wavefunction is ψ(x,t). Use the time dependent Schrodinger equation to show that ##\frac{\partial{\rho}}{\partial{t}} + \frac{\partial{j}}{\partial{x}} = 0## Where ##j(x,t) =...

Hi all, I've been self-studying a first year uni introductory mechanics course, and I'm confused with the derivations involved in calculating the final state of an elastic collision in one dimension, given the initial state. So basically we have masses of m_1, m_2 with initial velocities v_1i...