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Questions tagged [physics]

Questions related to the application of Mathematica to problems in physics.

1
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1answer
76 views

Conditional evaluation: black hole cross section

I'm trying to calculate the collision cross section of black holes, more precisely, I want the critical impact parameter $b_{\text{crit}}$ for a given initial velocity $v$ such that, at this speed, ...
2
votes
2answers
49 views

Finding the amplitude of function solved using ParametricNDSolve

I have been trying to find the peaks of a function I have plotted using ParametricNDSolve. I have to find these peaks to calculate the amplitude of all the various waves in the observed output. By ...
-1
votes
1answer
141 views

Working with motion equations

I'm trying to solve some Lagrange differential equations of motion, where $L = T - U$. Also, how can I use the solution for each x1, x2, x3, ..., xn? Here is my code: ...
11
votes
2answers
708 views

Solving “Resistance between two nodes on a grid” problem in Mathematica

In the context of resistor networks and finding the (equivalent) resistance between two arbitrary nodes, I am trying to learn how to write a generic approach in Mathematica, generic as in an approach ...
1
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1answer
64 views

Solve Euler Lagrange equation of motion DSolve

I'm trying to find Euler Lagrange equation of motion. then DSolve the equation for list of variable x1,x2,x3,x4 Here is my code: ...
0
votes
1answer
1k views

How to obtain differential equations of motion using Lagrangian dynamics?

I'm confused to find a set of differential equations of motion of a pair of masses, m1 and m2 joined by a spring of constant <...
2
votes
0answers
43 views

Symbolic perturbation expansion for quantum mechanics using Hellmann-Feynman derivaties

I am interested in some quantum mechanical perturbation expansion for energies. Actually I want to implement these terms $E_n^{(k)}$. As is stated below one can do that using CAS. I would be ...
6
votes
1answer
474 views

Radial distribution function (pair correlation function) for particles in rectangular image

Some time ago I asked the following question on how to calculate the radial distribution function. I have here an add-on question, but before asking it I try to summarize and visualize my problem. ...
2
votes
0answers
80 views

Using Image Transformation to create image sky view of what its like to be near black hole (Not a wormhole) [duplicate]

Question : I am trying to carry out point 3. "Implementing map" on page 13 in the paper Interstellar wormholes using my own equations not those in the paper. however am not 100% sure on how to go ...
0
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0answers
56 views

Calculating forces on a truss

I need to find certain forces of the truss shown above, and I am asked to calculate the forces with a matrix. The given values are ...
1
vote
1answer
80 views

A program for finding the summation of an analytical expression

Consider the Baker-Hausdorff formula for two operators $A$ and $B$: $$e^BA e^{-B} =A+[B,A]+\frac{1}{2!}[B,[B,A]]+\frac{1}{3!}[B,[B,[B,A]]]+....,$$ where $[A,B]=AB-BA$. In the case of my problem, $[B,...
0
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1answer
86 views

Integrating Hamiltonian equations using NDSolve

Would someone be able to integrate numerically the equations at the bottom of page 12 in the paper Interstellar Wormholes given some initial conditions of your choice. Reading the first paragraph of ...
0
votes
1answer
82 views

Creating a numerical table of values from an interpolating function resulting from NDSolve [on hold]

I am trying to carry out point "Implementing Map" on this paper Interstellar wormholes however I am using my own equations not those given (only the same method). Part 1 I am trying to create a ...
5
votes
1answer
241 views

Integrating Hamilton's equations for the Schwarzschild metric

Part 1 I am trying to integrate Hamiltons equations for the Schwarzschild geometry using NDSolve, these equations must all be integrated simultaneously and are nice ODE's. A similar task is done in ...
5
votes
1answer
581 views
0
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0answers
77 views

Numerical integration: gravitational force

What I would like to accomplish is to numerically integrate the following equation: $\nabla^{2}\Phi(r)=\rho(r)$, to get $\nabla\Phi(r)$. $r$ is the radial distance from the origin. Suppressing the $...
0
votes
0answers
56 views

Heat conduction problem with boundary at $\infty$

This is a 1-D heat conduction problem for a circular rod with 5cm, $T(x,0)=0$, $T(\infty, t)=0$, left boundary is insulated. I am trying to use the finite numerical method. My first question is how ...
0
votes
1answer
77 views

How to graph acceleration from an equation given a sample period?

I am unfamiliar with Mathematica and the necessary syntax to approach visualize acceleration over time. I would appreciate some assistance or reference to a starting point on how to go about solving ...
14
votes
1answer
1k views

Frequency domain Maxwell equations with PML boundary conditions

I'm trying to solve a full-vectorial wave equation for an arbitrarily shaped wave guide, by using NDSolve and perfectly matched layer (PML) conditions. The PML ...
3
votes
2answers
115 views

Carnot cycle diagram

Note: I have adopted and modified code taken from Wolfram demonstration page. I want to achieve something similar to the following figure: I use the following code: ...
1
vote
2answers
103 views

Validating a solution for a differential equation with DiracDelta

For the following differential equation $\displaystyle-\frac{\partial ^2\phi2 (x)}{\partial x^2}+\lambda ~[\phi2 (x)]^3-\mu ^2~\phi2 (x)=\phi2(x)~\delta(x)$ ...
2
votes
1answer
50 views

How do I draw an angular vector field containing a domain wall?

Intuitively, an angular vector field $\theta(x)$ such as the following would describe a domain wall between two vortices/strings of opposite winding number. I would like to draw this on a computer ...
4
votes
1answer
271 views

NDSolve aborted

I'm trying to simulate the formation of vortices in a BEC condensate with Mathematica. This problem was solved a long time ago (see this paper). After making several experiments and changes in the ...
0
votes
0answers
22 views

FeynCalc example — muon decay — integration issue

I'm just starting out using Mathematica and I'm trying to work through one of the examples given for FeynCalc, specifically the muon decay: https://github.com/FeynCalc/feyncalc/blob/master/FeynCalc/...
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votes
2answers
36 views

a ListAnimate problem

Thanks to @AlexTrounev, I learned how to use ListAnimate, but I still get stuck using it. Before ListAnimate everything is correct. I just cannot successfully use ListAnimate to make the plot. I have ...
0
votes
1answer
92 views

Animate particle's trajectory

Does anyone know how to animate the trajectory of a particle, but make sure before the particle reaching a certain spot, there's nothing. I mean I want to make an animation that look like https://en....
31
votes
4answers
3k views

Dynamic Euler–Bernoulli beam equation

I am trying to solve for the vibration of a Euler–Bernoulli beam. The equation is $\frac{\partial ^2u(t,x)}{\partial t^2}+\frac{\partial ^4u(t,x)}{\partial x^4}=0$ For the boundary conditions I ...
1
vote
1answer
75 views

Euler-Bernoulli beam equation

I'm trying to solve Euler-Bernoulli beam equation with simply supported edges.$\frac{\partial^2} {\partial x^2} [ E I \frac{\partial^2 w} {\partial x^2}] + \rho S \frac{\partial^2 w} {\partial t^2} = ...
13
votes
3answers
842 views

Time evolution/dynamics of circular plate with hole (Biharmonic equation and stiffness)

On this Mathematica.SE form, there exists information on how to use Mathematica to demonstrate the vibration of a circular membrane and the deflection of an orifice plate (the latter I had raised ...
0
votes
0answers
6 views

Using manipulate in the plot of a function that depens on a FindRoot function [duplicate]

I've the following two codes: FindRoot[Abs[Uin*Sin[2*Pi*fin*T - (Pi/2)]] - 2*Ud == (Uin - 2*Ud)* Exp[-T/(c*Rb)], {T, 1/(4*fin), 1/(2*fin)}] And: ...
1
vote
0answers
55 views

Trying to compute the heat capacity for the 2D-Ising model

I'm trying compute the heat capacity $C_v$ out of my simulation for the 2D-Ising model which is given by $C_v = \frac{\langle E^2 \rangle - \langle E \rangle^2}{T^2N^2}$ ($E$: Energy, $T$: ...
0
votes
0answers
32 views

How to simplify my integrand to make the function Integrate[] work?

To calculate a physical field, I need to integrate a complicated expression, with Sin and Cos and some 3/2 power. But when I run the Integrate function, it seems running forever. So what could I do to ...
1
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0answers
45 views

Abstract derivatives in Feyncalc

I have encountered several problems regarding the application of formal derivative operators in FeynCalc, using the built-in function FCPartialD, Left/RightPartialD Schematic description of my ...
0
votes
1answer
924 views

Animating a parametric plot

I am attempting to animate my parametric plot, but am having difficulties. I tried simply wrapping the plot code with an Animate[expression,{t,0,5}], but that hasn'...
1
vote
0answers
53 views

Integrating wavefunctions over a sphere

I am attempting to numerically solve the inner product of two particles and an electric dipole interaction potential. I am incredibly limited in my skills, and need to know how I can begin setting the ...
2
votes
1answer
157 views

Interpreting Mathematica code on black holes

I am trying to understand the code written down on page 7 of this document (code is in Mathematica) I understand pretty much all of the code on the previous page needed to setup the page 7 code (...
2
votes
0answers
51 views

Antiparticles in Feynrules Lagrangian

I am trying to implement a simple extension of the SM to Feynrules, generating the Lagrangian in a Mathematica notebook file. I am wondering about the following: Is there a way to explicitly use the ...
0
votes
0answers
46 views

Solve nonlinear differential equation system - Plot

When I solve the system of differential equations I get two solutions for each variable (See the picture). My question is how I can neglect one of the solutions at the plot. Thanks. Code: ...
3
votes
1answer
102 views

Using DSolve to solve an integral equation

I've the following integral (or DE) that I need to solve (for $x(t)$ and all the constants are known, real and positive): $$k\cdot\theta\left(t-m\right)+(n-k)\cdot\theta\left(t-v\right)=$$ $$x(t)\...
0
votes
0answers
75 views

Solving a differo-integral equation [duplicate]

I've the following equation for x(t): $$x'(t)\cdot\text{a}+\text{b}\cdot\frac{x'(t)}{x(t)+\text{c}}+\frac{\partial}{\partial t}\left\{\int_0^tx(\tau)\cdot\mathcal{...
1
vote
1answer
97 views

Rotation in physics [closed]

I have a mathematica problem in theoretical physics: There is a rotation axis $\vec{n}$ with $|\vec{n}|=1$. Each other vector $\vec{v}$ can be seperated in relation to $\vec{n}$ in a parallel part ...
8
votes
2answers
1k views

Adjusting Density Plot Color Function for Diffraction Simulation

I'm trying to simulate Fraunhofer diffraction by a single slit using DensityPlot I run the code: ...
2
votes
1answer
64 views

center of mass, total momentum

Has someone an idea how to solve the 1. question for ANY number of mass points and a clue to the 2. question? center of mass system, momentum
0
votes
1answer
80 views

center of mass system, momentum

when I have systems with 3 mass points ($m_i, i=1,2,3$) to a time $t=t_0$ on positions $\vec r_i(t_0)$ and velocity $\vec v_i(t_0)$. How could a syntax look like to calculate 1) center of mass 2) ...
1
vote
0answers
55 views

Decay chain browser

This https://demonstrations.wolfram.com/IsotopeBrowser/ used to be an excellent tool to demonstrate decay chains to my students. Unfortunately it does not work under newer versions of mma. Can anybody ...
4
votes
2answers
237 views

Solving a nonlinear system of ODE with DSolve

I have been trying to solve the following system of ODE with initial values using the function DSolve. My code is : ...
0
votes
1answer
72 views

trajectory of a thrown object [closed]

I have a equation of motion v(t), that is integrated (t=0) to x(t). This symbolizes a trajectory of a thrown object. I want to create compared Plots for x(t) with different values for beta. When I try ...
3
votes
2answers
118 views

Initial values of position (x) and speed (v) of a particle visualizing using Mathematica

$$\vec{F}(\vec{r})=-m\omega^2\begin{pmatrix}x\\4y\end{pmatrix}$$ I have the force $F$ shown above. How could I specify the initial values of position ($x$) and speed ($v$) in Mathematica using the <...
2
votes
0answers
42 views

HypExp and HPL packages for hypergeometric functions: Evaluating a function HPL[{minus,plus},x]?

I am currently using the HypExp and HPL packages, which are useful for expanding hypergeometric functions in series around integer or half-integer values, as in common in dimensional regularization ...