Element Definition and 836 Threads

Hello I just want to ask that in problem 1.54 why the sign of area element da is negative how do we predict signs in spherical coordinates unit vectors can anybody tell me the rule I have only trouble in sign like in left face it is negative what rule do we use for this negative sign

Consider the following tree-level Feynman diagrams for the ##W^{+}W^{-} \to W^{+}W^{-}## scattering process. The matrix element for this diagram can be read off from the associated quartic term ##\mathcal{L}_{WWWW}## in the electroweak boson self-interactions, where ##\mathcal{L}_{WWWW} =...

Hello! I'm starting a project with one of my professors at college whose subject is the Boundary Element Method. I've studied a little bit of Finite Element Method, but BEM is new to me. This project will envolve a lot of programming in Python and Matlab. I would like to know how does BEM...

Homework Statement Prove that a group has exactly one idempotent element. Homework EquationsThe Attempt at a Solution So we need to show that the identity element is the unique idempotent element in a group. First, we know that by definition of a group there is at least one element, e, such...

Joseph A. Gallian, in his book, "Contemporary Abstract Algebra" (Fifth Edition) defines an irreducible element in a domain as follows ... (he also defines associates and primes but I'm focused on irreducibles) ... I am trying to get a good sense of this definition ... My questions are as...

Joseph A. Gallian, in his book, "Contemporary Abstract Algebra" (Fifth Edition) defines an irreducible element in a domain as follows ... (he also defines associates and primes but I'm focused on irreducibles) ... I am trying to get a good sense of this definition ... My questions are as...

Hello everybody! I am excited to be part of this forum. It's the first time for me. I am 41, from France and with my sons (9, 7 and 6) we love physics. I have studied economics and discovered my interest for physics only a few years ago. I try to learn things by myself with videos from You tube...

Is Iron the heaviest element a star will fuse through nuclear fusion or will it continue to Iron into a heavier element.

Using : Ansys Workbench 16 Educational I want to build simple frame and simulate stress state and deformation when that frame is lifted. I have constructed my geometry in Design Modeler using line body's. My lifting cable has circular cross section with diameter of 10 mm. My frame has square...

I'm searching for a way to add/delete an element in a div in my html code. So far I have only found ways to replace content of existing elements. <div class="example"> empty... </div> how would I do this?

Most modern living rooms feature a large flat screen TV. Now with roll-able screens o the horizon people will be able to store the TV in closet and bring it out when they want to watch. Personally I welcome this concept as I think TVs as room elements are ugly and distracting...

Let's say we have 3 elements a,b, and c. a is right above b and b is right above c. Their heights change. What code would I use to position them since exact heights are not known and each elements must be relatively positioned to the previous element except "a" which is set at the top.

The following code works successfully and centers my image on the page (CSS) #box { display: block; margin: 0 auto; } This one does not (CSS) img { display: block; margin: 0 auto; } HTML <div id="box"> <img src="title.png" style="width:40%"> </div> I'm confused why it...

I put a tumble dryer that had been used only a few times back in operation after a decade being completely out of service. Heating failed shortly after switching on. Checked the heating element and noticed that it is broken at a dozen locations. The spiral is very brittle and breaks easily when...

I'm trying to make a simple HTML page that has a few elements. The problem is that when I zoom in using the mouse wheel and holding down Ctrl everything starts to go all over the place and it just looks completely mixed. I tried to find solutions to this but have had no luck so far. I want my...

In Schwartz's book, 'Quantum Field Theory and the Standard Model' P.696, he starts to derive an expression for a parton distribution function in terms of matrix elements evaluated on the lightcone. Most of the derivation is clear to me, except a couple of things at the start and midway. The...

I've been looking all over the internet for the line element of the Misner solution to the Einstein Field equations, but I can't find it. Can someone please post the line element? Thank you.

hi everyone, i need some help with my project that is DC rice cooker. i have the same problem for my calculation and logic cause my rice cooker use 12V and 100Watt. is that mean i need to use 8.3333Amp for the current? or i need to design a circuit that can reduce the amount of current needed...

Well firstly let me say that I am no expert but it seems like the number of protons that determine the different elements is like a puzzle made by the universe? I mean they are all in sequence... am I missing something?

Homework Statement Let c be a primitive 16th root of unity in the field of complex numbers. Show that c is a constructible number. Homework EquationsThe Attempt at a Solution I showed that c^2 is a primitive 8th root of unity and c^4 is a primitive 4th root of unity, so if I can show that one...

When choosing between a 2D 4-node quadrilateral element and 8-node for FEA stress analysis, why is the 8 node option preferred? I understand it has much more flexibility with different shapes due to the central mid node but are there any other reasons?

Homework Statement The only things you know about the sample are: (i) it has some kind of cubic lattice, and (ii) it is a pure element. Identify the element in the crystalline sample. SC: R = 0.5a FCC: R = 0.25a√2 BCC: R = 0.25a√3 Distances from Bragg peaks: d1 = 0.2037 nm d2 = 0.1746 nm d3...

Hi PF! Suppose we have a differential area element ##dA##. This can be expressed as ##dx \, dy##. However, a change in area ##dA## seems different. Take positions ##x## and ##y## and displace them by ##dx## and ##dy## respectively. Then the change in area ##dA = (x+dx)(y+dy)-xy = xdy+ydx##...

Homework Statement When an element of material is subjected to pure shear stress , equlibrium requires that equal shear stress must be developed on four faces of an element . Homework EquationsThe Attempt at a Solution I can't understand the statement . I assume the 'element ' is cubic ...

I was making a little bit of a thought experiment with a simple program and wanted to double check it with you guys. The idea was to utilize basic functionalities of python, regarding lists. Then the goal is to find out and print the number of times that a certain element occurs inside a...

Okay, I'm following a series of video lectures on applications of finite element method to engineering, and the tutor started by demonstrating the mathematical background of FEM using a simple heat transfer problem. He derived the governing equation (in just one dimension): (1)...

Homework Statement An electrical heating element is to be designed so that the power dissipated will be 750 W when connected to the 240 V mains supply. (a) Calculate the resistance of the wire needed. (b) The element is to be made from nichrome ribbon 1.0 mm wide and 0.050 mm thick. The...

Find a group $G$ that contains elements $a$ and $b$ such that $a^2=e$, $b^2=e$, but the order of the element $ab$ is infinite. My attempt: Clearly $G$ cannot be abelian. So I looked at two commonly known non-abelian groups, namely (i) The group of symmetries of the equilateral triangle (ii) 2...

Hi evryone, i have started to write an "algorithm" that finds the Family of a given element in a table of 3 columns: Id, Source and Destination. When i say Family i mean each element (i.e. A) from Source that has a relation with another one in Destination and i have to find a family for that new...

Hi, I have an HTML table and would like to insert mathcode into one of the rows after the page is loaded according to external data in files I'm loading. I've included script for MathJax and I'm trying to use: document.GetElementbyId("testInsert").innerHTML= but cannot get it to work with...

I was watching a video on Elon Musk. I believe he is a smart guy and he certainly knows is stuff. However, he said something in this video which I was surprised about and I can't seem to corroborate with various Google searching. Someone asked him whether there was enough Lithium on Earth to...

Does anyone know how to find the total mass matrix of two coupled element by using Finite Element Method?

Hello, thanks for your interest in may help me, i appreciate it, really. My question is, I've wrote this code to solve an physical EDO system. But for some reason it copies the element k[1][3] at k[2][3]. After i call the initials elements the code becomes: for ( int n=1 ; n<=1; n++ ){...

Let us see how the line element transforms under conformal transformations. Consider the Minkovski metric gij, a line element ds2=dxigijdxj, and a conformal transformation δk(x)=ak + λ xk + Λklxl + x2sk - 2xkx⋅s We have δ(dxk)=dδ(x)k=λ dxk + Λkldxl + 2 x⋅dx sk - 2dxkx⋅s - 2xkdx⋅s And so the...

So I just learned that in a spectrum like this one: (For now, let's concentrate on the graph given below.) The longer the dip is in the graph, the more the corresponding element is present. However, if each individual color corresponds to a different element, then how can a larger dip mean...

Hey! :o We suppose that $M/L/K$ are consecutive fields extensions and $a\in M$ is algebraic over $K$. I want to show that $a$ is algebraic also over $L$. I want to show also that the minimal polynomial of $a$ over $L$ divides the minimal polynomial of $a$ over $K$ (if we consider this...

what's difference between node & element & block in analysis software like Ansys?

Hi, What element should I use to model a tension-only (no bending stiffness) cable/chordae? The problem is that I need to use a hyperelastic material model with it. And LINK180 does not support the hyperelastic material model. Thanks!

Hi, guys. A type of problem that often appears is to find the relation between cross sections of some processes. An example would be: $$\pi _{- }+ p \rightarrow K_0 + \Sigma_0$$ $$\pi _{- }+ p \rightarrow K_+ + \Sigma_-$$ $$\pi _{+}+ p \rightarrow K_+ + \Sigma_+$$ To do this, I argue that...

Homework Statement Choose the element in each of the sets you would expect to have the highest IE2. a. K b. Be c. Mg d. Ca e. Al Homework Equations The correct answer is K The Attempt at a Solution I do not understand why it is K ...I kind of guessed by using my Ionization Energy diagram...

On page 284 Dummit and Foote in their book Abstract Algebra define a prime element in an integral domain ... as follows: My question is as follows: What is the definition of a prime element in a ring that is not an integral domain ... does D&F's definition imply that prime elements cannot exist...

On page 284 Dummit and Foote in their book Abstract Algebra define a prime element in an integral domain ... as follows:My question is as follows: What is the definition of a prime element in a ring that is not an integral domain ... does D&F's definition imply that prime elements cannot exist...

Hello! I have read (I don't remember the source, and have it only in my notes now) that oxo acids can be strong if Y element has a high electronegativity. If generic formula for oxo acids is HnYOm, than if Y has high electronegativity, it will cause the acid to become strong because Y will be...

Homework Statement We've got a line element ds^2 = f(x) du^2 + dx^2 From that we should find the geodesic equation Homework Equations Line Element: ds^2 = dq^j g_{jk} dq^k Geodesic Equation: \ddot{q}^j = -\Gamma_{km}^j \dot{q}^k \dot{q}^m Christoffel Symbol: \Gamma_{km}^j = \frac{g^{jl}}{2}...

I'm confused about energy driven by a wave. Consider a sinousoidal wave moving in a rope. Each element ##dm## of the rope follows a simple harmonic motion in time. That means that the mechanical energy ##dE=dK+dU## of the element ##dm## is constant. Nevertheless on Halliday-Resnik-Krane I...

Homework Statement Ok, these questions are very simple but they are really bugging me and I would greatly appreciate an explanation. Question 1 is "which of the following elements must have been made in stars". The options are hydrogen, helium, carbon, oxygen and iron. Question 2 is "which of...

We know, that the infinitesimal area element in Cartesian coordinate system is ##dy~dx## and in Polar coordinate system, it is ##r~dr~d\theta##. This inifinitesimal area element is calculated by measuring the area of the region bounded by the lines ##x,~x+dx, ~y,~y+dy## (for polar coordinate...

When finding the Von Mises of given a stress tensor who's only element is a single shear component (τ): \begin{bmatrix} 0 & τ & 0\\ τ & 0 & 0\\ 0 & 0 & 0 \end{bmatrix} the result is simply √3×τ. Is the Von Mises criterion not valid when considering a single component as in this example? I...

I have a a multidimensional array (49x49x49) which has NaN values scattered randomly. For each NaN, I want to replace the value with the previous non NaN value. e.g. if i had a 3 x 3 matrix 4 7 9 2 7 NaN 1 2 NaN should become 4 7 9 2 7 7 1 2 2 I have 3 dimensions [i,j,k], but...

Homework Statement Here, V is a vector space. a) Show that identity element of addition is unique. b) If v, w and 0 belong to V and v + w = 0, then w = -v Homework EquationsThe Attempt at a Solution a) If u, 0', 0* belong to V, then u + 0' = u u + 0* = u Adding the additive inverse on both...