Element Definition and 836 Threads

Hi guys, I wanted to know these things with their respective examples : 1. What is an atom ? 2. What is a particle ? 3. Why do we use/calculate the atoms of an element to balance an equation ? Please answer to these questions guys, because I only have 2 days for my exams and to know them.

Is it true that if a finite group G contains a subgroup of index 2, then there is an element of G with order 2?

Hi , I have a question that's confusing and difficult to comprehend " A heating element is placed on the floor and bag of water is placed over it. At present, A power of 300W is applied to the heating element. Peter, the technician, wants to increase the rate at which the water in the...

I am studying for a modterm on Monday and asking for help on the homework questions I got WRONG on my problem sets (so I can hopefully improve my understanding and see my mistake). This is my reworked version of the incorrect HW problem and I would like to know if I am on the right track...

Hi guys. I want to transfer each elements of an array (which is declared in one subroutine)to main function using common block technique. When i am doing so i go always a constant value in the array in the main function. Suppose i have one array bparz(i) which has different values in one...

Homework Statement I need to find the inverse to element in 7 in ring Z_{13} Homework Equations 7^-1 in Z_{13} The Attempt at a Solution Needs to find X so that, 7x=1 in Z_{13} => 7x=1+k*13 And then my notes was messed up :(

My lecturer used a symbol in class that represents an element being removed from a set to form a new set. Does anyone know what this symbol is?

Homework Statement X={4^n-3n-1/ n belongs to N} Y={9(n-1)/ n belongs to N } Homework Equations then, XUY is equals to X or Y or N or None of these

i understand that everything else is less as they are (in turn) made from hydrogen, but why was so much of hydrogen made in the big bang? i got a feeling because one proton and one electron is stable. (similarly, helium was produced as 2 nucleons + 2 electrons is also very stable) but I've...

It takes an infinite time for complete decay of a radioactive element. but on the same time we calculate the half life of radioactive material i-e T-1/2 = ln 2 / lamda. is that means that if we double the half life time we could reach the total life time of radioactive decay so on contrary we...

I want to build something like http://www.radioshack.com/product/index.jsp?productId=2911246", but much smaller and only heating a coil up to 185 C. It would need to last at least an hour, but be as compact as possible. Any suggestions?

Hello all, I am trying to create a simple finite element program in C++ and have been able to build and assemble the GLOBAL stiffness matrix as well as the load vector. I want to apply the boundary conditions using the elimination approach, can anyone tell me how to do this? I am sorry for...

Can anyone see what's not right? In the phase space calculation of a 2 to 2 process I get to I=\int dp_1d\Omega \frac{1}{(2\pi)^2}\frac{p_1^2}{2E_12E_2}\delta(E_1+E_2-E) then I use p_1=\sqrt{E_1^2+m_1^2} \Rightarrow dp_1=\frac{E_1}{\sqrt{E_1^2+m_1^2}}dE_1 thus I = \int dE_1d\Omega...

Hi everyone, I'm currently working on coding a finite element heat problem in Matlab that is as follows: I have a cross section of a beam made of an isotropic material (concrete) that is placed in a furnace, and the outside temperature is raised at a constant rate. I am interested in...

In consideration of a lone wire element of differential length dL carrying a current I: Two things concern me here: 1) Is a magnetic field generated by current I really limited to only spaces that exist orthogonally to the line between the two ends of the wire element? If not, what does...

Hello! I am trying to calculate the matrix element of the process where an incoming upp quark and gluon interact via an upquark and emit a photon and an upquark. ---u(p1)->--~~gamma(p3)~~ | | u(q) |...

Hello, I have to do stress analysis on a protection window at work but I am getting errors when meshing in ANSYS because of the element type I am choosing. The window is of course is a solid and is a wide, thin sheet. What Element Type should I use? Also, do I need to create nodes or not...

I can do all the question apart from the 'Conclude rt(2) in an element of Q(rt(2) + rt(3))' That's all I need help on. I tried rt(2) = a + b(rt(2) + rt(3)) squaring it and equating you get 2 = a2 + 5b2 + (some other terms of rt(2) rt(3) rt(5)) but this cannot be true for a, b...

How do you define what is a fundamental circuit element? I am not really sure, why isn't a transistor a fundamental circuit element. Can u consider a switch a fundamental circuit element or is it a resistor with infinite resistance.

Homework Statement L is the splitting field generated by x^2+x+1 (over \mathbb{Q}) a) Is \sqrt{-3} an element of L? b) Is sqrt(-3) an element of \mathbb{Q}(a), where a is a complex root of x^3+x+1? Homework Equations The Attempt at a Solution Really no idea.

As an example, for the sequence: s_{1} =2 s_{n+1}=\frac{s^{2}_{n}+1}{2} We see: When s_{n} >1 then, s_{n+1}=\frac{s^{2}_{n}+1}{2}>s_{n} But how do I formally show that this last inequality is true? This example is fine or just one similar to it. Thanks! EDIT: Many of those...

Firstly, sorry if this is in the wrong place. I'm new here. Seems to be an awesome site! :) Homework Statement Well, I've got to learn all these formulae (regarding the periodic table) and was wandering if there's any specific way to be able to understand when something is and Oxide or...

If I have SO42-, I can figure out that the oxidation state of each O ion is 2- and the sulfur ion must then be 6+. What does this number mean? What does it tell you about the electrons in that molecule?

Homework Statement a) Let V be a normed vector space. Then show that (by the triangle inequality) the function f(x)=||x|| is a Lipschitz function from V into [0,∞). In particular, f is uniformly continuous on V. b) Show that a closed subset F of contains an element of minimal norm, that...

Homework Statement i am trying to make an air flow meter using an heating element which i got from an iron..basically i have thought of inserting the element into a duct through which i will pass air using a blower,to connect the element with a 12v supply in series with a ammeter...thn i...

Hi Friends I am new to ansys. I designed a beam in Pro.E and save it in igs format and then open it in ansys now what element type i should use for this and why?

Element 117 has been synthesized: http://www.nytimes.com/2010/04/07/science/07element.html If the Island of Stability exists, and significant quantities of a stable element 126 could be synthesized, then what would be the practical applications of such a material? Could it be used for...

This story is over a year old, and a quick search on PF did not turn up any hits, and to me at least I think is worth a look: http://www.energydigital.com/Uranium-Star-Corp-Unearthing-new-power-source_31962" . I realize this is a marketing and sales pitch over the virtues of this strategic...

what is the chemical sign of antimony

Hi! I have an array that is 1 column by many rows, of which each element represents a time. I want to find variable f at each time, where f is defined as follows: if t < tp f=(sin((pi*t)/(2*tp)))^2; if tp < t < ts f=(cos((pi*(t-tp))/(2*(ts-tp))))^2; otherwise f=0 I've tried...

Design of heating element: Supply Voltage: 220V/3Ph/60HZ, Power: 9KW Resistance= VXV/P= 220X220/9000= 5.4 Ohms, But when physically when measure the resistance of wire using multimeter it is showing 17 ohms. Can you explain why there is differnece in practical and theortical value...

Hello! :-) I've been thinking about the RW line element (c^2 d tau^2), and I understand that there is a term which describes the geometry of the Universe (d sigma^2) and then a term corresponding to the cosmic time (c^2 dt^2). The resulting (c^2 d tau^2 ) term would be the line measured by...

in finite element analysis there is no poisson ratio for LINK ELEMENT (truss structure) just explain ?

Hey guys! I'm having some trouble trying to solve this question.. Any advice/help is appreciated! Homework Statement Suppose that a and b belong to a group such that: |a| = 4, |b| = 2, and suppose a3b=ba Find the order of ab. Homework Equations The Attempt at a Solution So...

Hi everyone, As part of a project, I am required to numerically compute the expression b_{i}^{e} &=& \frac{E_{0}^{i}k_0^2(\epsilon_r-1/\mu_r)}{2\Delta^e}\left[\iint\limits_{\Omega^e}(a_i^e + b_i^e x + c_i^e y)e^{-jk_0 x} dx dy\right] \nonumber\\&&- \frac{jk_0 E_0^i r'}{2\Delta^e...

Consider the free body diagram of a surface element of a water - glass meniscus in a vacuum. Along the line normal to the surface, the water pressure acts towards the vacuum, and the direction of the surface tension 'curvature force' depends on whether the surface curves like a 'u' or like an...

Hello new to the site and i usually don't post questions but after a few days searching I answered a few and found many more I'm hoping someone here can help. Background for project: Looking to preheat my RC (remote control) nitro motors to 200-220'F prior to starting the break-in process.i...

Does anyone know what the formula is for the following: <j m | S^2_{+} |j m > = ? Reference to equations in Sakurai would be helpful in deriving the relation. I would suspect 3.5.37 but what about the delta_j j' ? Does anyone know what I'm talking about?

guys..i need help... how to extract a maximum occurring element in array using perl... example... a[1]=11; a[2]=12; a[3]=13; a[4]=14; a[5]=15; a[6]=13; a[7]=14; a[8]=14; we will see that, 14 is the most occurring at element 8... how to know the no of frequently it...

I am trying to run a finite element analysis for a collision impact. The program I am using is MD Patran/Nastran. My model consists of moving object colliding with a stationary object. I have created the mesh, applied the appropriate material, applied the boundary conditions (fixed for the...

Homework Statement Simply like the title says, "If a is an element of R can you assume -a is an element of R?" R={All Real Numbers} Homework Equations N/AThe Attempt at a Solution I concluded that if a is a real number so must -a. Can that be assumed in a proof? Should a simple "If a \epsilon...

Homework Statement I am trying to calculate power dissipated over a cylindrical surface using poynting vector - \oint ExH ds I know ds for a sphere is r^2 sin \theta d\theta d\phi But now sure what ds is for a cylinder? Homework Equations The Attempt at a Solution

Can you guys explain to me what is the difference between least element and minimal element? I keep struggling to understand the difference between them but till now i still cannot resolved it. right now, i am trying to learn set theory, do you have any reference(book, link,whatever) that i...

Homework Statement The original problem has to do with telling messages encrypted with a version of the ElGamal public key crypto system apart. It relies on exponentiation in an arbitrary cyclic group G of prime order p with generator g. The public key is y = g^x where x is the private key...

Homework Statement let G be a group and let g be one fixed element of G. Show that the map ig, such that ig(x) = gxg' for x in G, is an isomorphism of G with itself.Homework Equations The Attempt at a Solution not even really understanding the question. can someone break it down for me, and...

Hi! I am currently taking a first course in QFT with Peskin & Schroeder's book. I've got stuck with the equation that relates the differential decay rate of a particle A at rest into a set of final particles with the invariant matrix element M of the process. M can be found from the Feynman...

Homework Statement Like, if you are writing out one of the blocks on the table of elements chart, you would write out the letter of the element, and then you would write the atomic average (or atamoic mass it is also known as,) on the bottom left , and the atmomic mass on the top to the...

So I was reading about lightbulbs... and if I broke the bulb so that oxygen came onto the heated filament, I understand that the tungsten would combust. But how would I figure out how much energy would be given off? Would this cause a fire? I have no chemistry training so be gentle!

I am on a research project where I am finding the heat capacitance and thermal conductance of a material and would like to simulate it on a larger scale as material for heated flooring. Is there a program where I can do a looping heating pipe at a set temperature and show the conductance of the...

Hi there, I have been doing research on a lil private project of my own, and am looking for some help. Would it make sense to use nichrome wire to build a heating element that will heat to 80-100 degrees? It seems that nichrome is great for heating way way past that temperature. I want to...