Element Definition and 836 Threads

Homework Statement If ##n = 2k## is even and ##n \ge 4##, show that ##z = r^k## is an element of order 2 which commutes with all elements of ##D_{2n}##. Show also that ##z## is the only nonidentity element of ##D_{2n}## which commutes with all elements of ##D_{2n}##. Homework Equations...

Hi what is the importance of element normals in a FE mesh ? How does it matter if it is outward or inward in a FE solver ? I came across Visual Crash Pam software in which negative element ids would mean element normals in opposite direction. how would this affect the overall result of an...

I have begun to learn about maximal elements from a linear algebraic perspective (maximal linearly independent subsets of vector spaces). I have a few questions of which I have been able to get few insights online: 1) Does every family of sets have a maximal element? How can I make a family...

Problem: Prove that if an element is in the union of two infinite sets then it is not necessarily in their intersection: Proof: Have I solved it correctly?

Homework Statement Hello Guys, I am reading Hobson's General Relativity and I have come across an exercise problem, part of which frustrates me: 3.20 (P. 91) In the 2-space with line element ds^2=\frac{dr^{2}+r^{2}d\theta^{2}}{r^{2}-a^{2}}-\frac{r^{2}dr^{2}}{{(r^{2}-a^{2})}^{2}} and...

Hello, I have Silicon Carbide heating elements which should be used with a Step Down Transformer or SCR as mentioned in the guide from manufacturer. I currently have a SSR available at hand, and was hoping it could be used instead. The Solid State Relay when connected to PID can...

Hi all! I have no application in mind for the following question but it find it curious to think about: Say that we have a square matrix where the sum of the elements in each row and each column is zero. Clearly such a matrix is singular. Suppose that no row or column of the matrix is the...

I want to inspect element in my android browser. How do I do that. I have a stored password (yes it's mine, not someone else's) that I want to see. On my laptop, its easy using chrome. But how do I do that on the android browser? Is there any way to change the URL such that it affects the...

I've just been reading a little bit about attempts to create element 120 back in 2007. Do you guys think that it will be possible to create such an element?

Homework Statement Subject the "PR2" from the following equationHomework Equations Tpwm = [(PR2) + 1] • 4 • TOSC • N • = multiply The Attempt at a Solution Actually I am not a student As well as I know how the equation after subject the "PR2"... PR2 = [Fosc / (Fpwm * 4 * N )] - 1 where(...

1.The equivalent weight of an element is 4.It's chloride has a V.D.=59.25.Find out the valency of the element Homework Equations 3.Molecular wt=108.50 u.Then how to proceed?

Hey guys, I was working on something today and I was trying to formalize what I was doing, and I tried to write out: M = { x | ( 2 / x ) \in M } Then I thought about it and wondered whether this is allowed in set theory. Its not clear that there is anything in M at all, and thus its not...

In reading about the axial anomaly I stumbles across a matrix element on the form $$\langle p,k|j^{\mu 53}|0\rangle. $$ and I have seen similar matrix elements turn up other places. But when matrix elements (correlation functions) of the form $$ \langle 0 |T \phi(x) \phi(y)|0\rangle $$...

Hi guys. Just wondering. What element that can't pass through light? By the way I finished computer science so I don't know much about physics. Thanks in advanced.

Homework Statement Consider the problem $$-u''\left(x\right) = 1, \;\; 0 < x < 3, \;\; u \left(0\right) = 0, \; -u' \left(3\right) = u\left(3\right)+1.$$ Formulate a MATLAB code to produce the solution and plot the solution from 0 to 3. Homework Equations The Attempt at a Solution Multiply by...

Hi, so I have a homework problem and I don't know how to approach. I am given a circuit, with an AC source, a resistor ( 2 Ω) and a unknown circuit element (that could be an inductor or a capacitor). I am also given a graph with the Voltage amplitud across the AC source (Which happens to be...

Quick question on eigenvectors; Are there any general properties of a matrix that guarantee that a zero will or will not appear as an element in an eigenvector? Thank you!

Howdy, I am trying to formulate a proof to show that the shape function [N(x,y)] = [Ni(x,y) Nj(x,y) Nk(x,y)] and the the basis functions Ni(x,y) = (1/2A)(ai + bix + ciz) Nj(x,y) = (1/2A)(aj + bjx + cjy) Nk(x,y) = (1/2A)(ak + bkx + cky) are valid for triangular, 2 dimensional...

What is the difference between the line element and length of a four vector? They both seem to have the same definition just with slightly different notation, so is the line element just the length of a specfic vector. Also, if the magnitude of a four-vector is calculated to b -1 is this...

Homework Statement When an electron drops from the M shell (n = 3) to a vacancy in the K shell (n = 1), the measured wavelength of the emitted x-ray is found to be 0.0897 nm. Identify the element. Homework Equations E = 1240 / λ E = (-13.6 / n^2) * (Zeff^2) The Attempt at a...

Anyone know of some good, free finite element analysis software? I used NASTRAN in college, but from what I can tell that costs at least several thousand.

I'm working on showing that Z3 is a ring. The one portion I'd like to confirm is the additive inverse part. So here's what I'm thinking as my proof: Given [x]3 , suppose [3-x]3 is the additive inverse in the set Z3 . Thus: [3-x]3 = [3]3 + [-x]3 = [0]3 + [-x]3 = [0-x]3 = [-x]3 Then, it...

I am just curious Is there an element/alloy that heats up when exposed to a radioactive element

Hey all, First post, thanks in advance for any help. I see there is a lot of discussion on this site and others about nichrome heating elements. I apologize if my question is very similar to others, but I have not exactly been able to figure out what I need to learn/lookup to answer my...

Homework Statement So I am having a hard time trying figuring this out. The question asks for the current through the 20Ω resistor as well as the current through the battery AFTER THE SWITCH HAS BEEN CLOSE FOR ALONG TIME. Here is a picture of the circuit. http://i.imgur.com/VjoFSUd.jpg...

Folks, I have attached a picture illustrating the labelling of the linear reactangle element which can be represented by the following equation ##u(x,y)=c_1+c_2 x +c_3 y +c_4 xy## (1) ##u_1=u(0,0)=c_1## ##u_2=u(a,0)=c_1+c_2a## ##u_3=u(a,b)=c_1+c_2a+c_3b+c_4ab##...

..though I figure it's sort of an analysis type problem. ∫wvdx=0 (int from 0 to 1) for all v in V. w is continuous on [0,1]. What it means to be in V: v in V satisfies being continuous on [0,1], v(0)=v(1)=0, and derivatives of v are piecewise continuous . Problem is: Show that w(x)=0 for x in...

Hi there, This should be very simple... If I have a state <1|AB|2> where A and B are Hermitian operators, can I rewrite this as <2|BA|1> ? That would be, taking the complex conjugate of the matrix element and saying that A*=A and B*=B. Thank you!

Calculate the number of elements in A1 U A2 U A3 if there are 97 elements in A1, 997 elements in A2 and 10098 elements in A3 in each of the following situations: (a) The amounts are pairwise disjoint, i.e. , too . (b). (c) there are 10 elements in common for each pair of volumes and 4...

I am using an heating element to heat the air in a closed container. Joule heating will give me the "heat generated at heating element." I want to know how much of it will be transferred to the surrounding air. Should I be using heat transfer due to all three modes ?

Consider a fissile element whose magnitude is at the order of a neutron. In this situation, how can we derive the point kinetic equations? Thanks everyone.

Homework Statement Hey all. I have code that is supposed to delete the offset determined by the user and shift the elements after that offset to the left. My code works fine except for one problem: if the index is zero it terminates. I will post my code, and if anyone can see why it is giving...

Homework Statement Let G be a finite group in which every element has a square root. That is, for each x in G, there exists a y in G such that y^2=x. Prove every element in G has a unique square root. Homework Equations G being a group means it is a set with operation * satisfying...

Homework Statement True or False? Every infinite group has an element of infinite order. Homework Equations A group is a set G along with an operation * such that if a,b,c \in G then (a*b)*c=a*(b*c) there exists an e in G such that a*e=a for every a in G there exists an a' such...

Previously I never noticed that we are making this abstraction - to abstract continuous systems into an idealized discrete element like resistor or capacitor. So since we have made this approximation, what kind of errors can occur in our calculations? Does this approximation ever fail so that...

I want to why actually elements are eliminated in commercial fea solvers. There is a criterion like stress or strain at which elements having acheived that state are eliminated. Wouldnt it lead to wrong results because, the material at eliminated elements place has become null.

I really don't know how to do this question as it asks me to write the surface element of a hemisphere in xyz coordinates. I know how to answer if it is asked in spherical coordinates. I think this is a tricky question because it asks for the portion da near (0, A, 0) (in xyz) where A is the...

Hey, I had two separate questions. (When I say Z*(n) I'm denoting the multiplicative group of integers mod n, namely, the units of Z(n)) First off, I know that if n is prime, that Z*(n) is cyclic. But this is not a biconditional statement. Is there any theorem which tells me conditions under...

Homework Statement Hello, we are starting to get to Banach spaces and thus linear normed spaces in a functional analysis class and I am realizing that I don't have much experience or intuition with these spaces. So I was reading over the requirements for a linear space in my notes and was...

Once again, my textbook seems to do a poor job of explaining another concept just like I commented earlier here. Anyways, here is the relevant part of the textbook: http://www.mediafire.com/view/?cw5t2wr9vqqprnv To calculate p4 in example 1.7, voltage of 8V is multiplied by a current of -0.2I...

Homework Statement I have the following practice problem which is presented as follows: What is the size of the global stiffness matrix K (i.e., Kuu) for the 2-D problem? http://imgur.com/KZec3 (Unsolved) http://imgur.com/piv1J (Solved) Homework Equations The Attempt at a...

Hi there! I recently noticed that the little drainage tube in the back of my fridge keeps blocking up with ice. As a result massive condensation develops around the ice which eventually drips down the back causing the bottom of the fridge to fill with water the whole time. Apparently the...

I need help with this theorum, please. How is this (the attachment) true? It's for my cryptology class. The rest of the day's notes are here: http://crypto.linuxism.com/thursday_december_13_2012

Hello everybody, hopefully I am posting this in the right spot. What I am trying to do is design a heating element powered by a Li-Po battery (RC battery probably) to heat a heating element to a range of 360-420°F. I want the temp to be adjustable, probably on three settings, so one for 360...

Hi, I'm trying to work with the Biot-Savart law to look at the magnetic field strength along the center of an asymmetric solenoid I wrapped. I parameterized the coils with x = r cos 2(pi)t, y = r sin 2(pi)t, and z = D t where r is the radius of the coil layer, D is the diameter of the wire...

Converting binding energy of an element to joules! [SIZE="4"]The binding energy of Mg-24 is 198MeV. What is this value in Joules? Write your answer correct to three significant figures. MeV = megaelectron volt 1 megaelectron volt = 1.60217646 × 10-13 joules 198 megaelectron volts =...

Sorry about the long title. I recently had a few homework problems which were similar to the title of the post. I struggled a bit with them so I'm trying to find additional problems to work on until I can master these ideas... Basically, if we have a group G s.t. |G|=n, and we know G has a...

Homework Statement The problem picture is attached(file 1),its a beam subjected to horizonatal ditributed load 2. Relevant examples the MATLAB solution for rectangular shape with vertical load on the upper right corner is like follow, i try to modify it according to the new picture...

Me again, (this is what happens when you make a designer do mechanics, and give her a lecturer she doesn't understand :P ). I'm stuck on a combined loadings question. This is the question: "The 60 mm diameter rod (fixed at end C on the wall) is subjected to the loads shown. 1) Transform...

Hi, Recently started with FEA - loving it, at least the modelling / load application part. Interpreting the results is tricky - particularly around where loads are applied. Got a project (no pics sorry) which has a drilled hole in a plate, and have applied the load as a a pressure...