Element Definition and 836 Threads

Is there an element that does not decay but can be identified from a extremely far distance or an element with a multi-billion year half life

Hi guys I wish to self-study the Finite Element Method. I am mostly interested in learning how to understand and implement the method rather than to investigate if a solution exists, i.e. I wish to follow the "engineering-approach" rather than the "mathematician-approach". Do you have any...

Hi everyone, I have to prove that every element z of a finite field F is a sum of 2 squares. Really not sure how to go about proving this, though I've done some research and it is suggested to start with a function that maps F* to itself, defined by f(x) = x^{2} . I guess if I could show...

Homework Statement The domain D is a tetrahedron bounded by the planes x = 0, y = 0, z = 0 and x + y + z = 1 Calculate (a). The volume of the domain. [10 marks] (b). The x-coordinate of the centre-of-mass of the domain, assuming constant density. [9 marks] (c). Find, in terms of x and y the...

Mathematics and ordinary language cannot show that a set of signs is not mathematical or semantic. For example x+2=2x-2. This set of signs is assumed to be a mathematical expression by working with it, mathematically, to assess it for truth or falsity. The conclusion, that the set of signs...

Hello Everyone, I've been looking for an answer to problem I have and I'm getting nowhere so I thought asking the question in a place like this might be useful. I'm planning to build a kiln. I have refractory material that can sustain 1500 degrees celsius. I'm trying to choose an element...

i have few doubt regarding a single element set. let X={0}, in euclidiean metric. my questions are: 1. does matric space even matters? or matric space is defined? 2. is this set open/closed/none of them? 3. for a discrete matric on [0,1], [0,1]= {0}+(0,1] = {0}+(0,1)+{1}, then {0},{1} are...

My textbook (Abstract Algebra by W.E. Deskins) says that the order of an element of a group is equal to the integral power to which it must be raised to equal the identity element. It also says that the order of the generator of a cyclic group is equal to the order of the group it generates...

I've been trying to figure out the volume of an element in k-space (free electron gas in a crystal lattice). In deriving the density of states, dn/dE = dn/dk . dk/dE. My dn = 4pi(k^2).dk / V, where V is the volume of an element in k-space. I came across the spurious, Dk.Dx ~ 2pi (an...

This is not a homework problem in itself. In my physics homework, I wanted to write the difference of two areas (thus yielding a differential disk) as: Pi*(r+dr)2-Pi*r2 It reduces to 2*Pi*r*dr+Pi*(dr)2 Now, I seem to recall from a prior class that a quick hand-waving made (dr)2 =...

Homework Statement Consider the two-dimensional spacetime spanned by coordinates (v,x) with the line element ds^2=-xdv^2 +2dvdx Calculate the light cone at a point (vx) The Attempt at a Solution I don't even know how the light cone for flat spacetime is calculated. So if that one's...

Hi, Say I have a 10x10 matrix, is there a simple code to finding the indices of the maximum value? I'm trying to use max() but there doesn't appear to be any option of actually returning the index, rather than the value. I don't need the value, just the position. Thanks, Mike

I am doing BE in mechanical engineering. I'm looking for a comprehensive book on finite element methods preferably with a lot of solved numericals . Suggestions, please?

One of my friends is insisting that a car can go 19000km with only 1kg of http://en.wikipedia.org/wiki/Borax" , and only one tea-spoon of borax can extract as much energy 100 tons of coal does. Is that true? Does borax contain this much of chemical energy?

Homework Statement Prove that the element dt\ dx\ dy\ dz is invariant under Lorentz boost with velocity \beta along z axis. Homework Equations Convention c=1 Lorentz boost in z direction: L(z)=\left[ \begin{array}{cccc} \gamma & 0 & 0 & -\gamma\beta \\ 0 & 1 & 0 & 0 \\ 0 & 0 & 1 & 0 \\...

I need a solution for healing tree grafts. Fruit trees are often propagated in the spring by grafting (attaching) a piece of scion wood to rootstock. The graft must "heal" which means that the outer "cambium" layers of the two pieces join together. This process occurs around room temperature...

Homework Statement Calculate the differential cross section for A+B---> C+D with an invariant matrix element Homework Equations See attachment The Attempt at a Solution I have no idea how to even begin this problem. The course I am taking is an undergraduate course in intermediate modern...

Let p be a prime, k a pos. int., and G a group with |G|=p^k. Prove that G has an element of order p.

Homework Statement Hi guys Is there a difference between finite element methods and finite volume methods? Or do they both rely on each other? Niles.

i am a 3rd year civil engineering student, currently taking a course in which i need to use finite element software for assignments. the course is 100% theory, and i need to learn how to use the software on my own, i am looking for FREE software with FE capabilities, and preferably one that...

Homework Statement Prove that in any group, an element and its inverse have the same order. Homework Equations none The Attempt at a Solution I know that I need to show |g|=|g^-1|. This is how I approached it but I'm not sure I'm right, it seems like I'm missing something. Let...

Since atoms above a certain atomic number are unstable and have an extremely short lifespan, then the atoms of the unknown element that comprises the mass of a collapsing star in the process of becoming a black hole just before the stage where a singularity is achieved should by all accounts...

Hi there, I have completed my analysis in BEM. The results gives me velocity potential in form of 37954305E-04 +1.58625295E-06 +2.10275811E-07 +... I have real scattering values, imaginary and absolute scattering values in this form. I am new to the method and from a different...

Unable to "decrypt" emission/absorption matrix element Hi to everyone! I'm reading an example of atom radiation interaction (more precisely, an atom emits a photon which photoionizes another atom) on an old book (60s) and I'm facing a matrix element which I never saw. I mean, I'm not able to...

When using BJT as a pass element in series pass regulation, why is the NPN drop more than the PNP. Both have BE diodes. Why is the drop (VCEsat+VBE) in case of NPN and drop is equal to VCE sat in case of PNP. Can someone also explain VCE sat using diode equivalent of BJTs.

Homework Statement Determine whether the operation has an identity element. x*y = 3xy Homework Equations e*x = x*e = x, if this holds, e is an identity element The Attempt at a Solution My attempt: x*z = z*x = 3xz, then 3xz = x <=> z = 1/3 => e = 1/3. But the answer key in the...

Homework Statement Light emitted by Element X passes through a diffraction grating having 1200 lines/mm. The diffraction pattern is observed on a screen 75.0 cm behind the grating. Bright fringes are seen on the screen at distances of 56.2 cm, 65.9 cm, and 93.5 cm from the central maximum. No...

hi guys I am looking to find a source of radiant heat about 2 inches wide and 6-8 inches long and i got to thinking if i hook up 8 AA batteries in series it should produce 12v needed to power the element of a water heater, my question is will this power source work to run the element? thanks

do suggest a good book for finite element method?some books have left me confused over the various methods

Curious question, figured what better place to ask than the physics forum. So I just picked up a used hot tub. Was running great when I bought it. Filled it up with water, turned it on, started its cycle. It can take over 24 hours for the tub to reach 102 degrees. There's a 12 inch...

Homework Statement Construct a finite field of order 16. And find a primative element. Homework Equations The Attempt at a Solution What I did was find an irreducible polynomial in Z/<2> of degree 4. I used f(x)=x^4+x+1. Then I took a to be a root of f(x) and set a^4=a+1...

I'm finding it hard to frame my question in the right words as I'm an English learner. So, I hope you would be able to get to the main point using your own understanding and interpretation. Thanks. When I was a kid I used to love playing video games. I think I still would love to but couldn't...

Homework Statement http://img137.imageshack.us/img137/355/circuit2.png Homework Equations P=VI P=I^2 R V=IR The Attempt at a Solution The part a is all correct. i_\wedge = 5A i_o = 2A v_o = 80V This is what i have done in part b but it is not correct because P_delivered not equal to...

Hi all, I have question regarding to heater I want to build. It suppose to be a heater used for soldering a thin copper sheet (1mm thick) with other small copper components. Heater has to be flat as much as possible and reach the temp up to ~250C (solder melting point). The copper sheet...

Homework Statement Given a a group of order 30 w/ a non-normal Sylow 5-subgroup, the problem is to count the number of elements of orders 5, 3, 2, and 1. Homework Equations The Attempt at a Solution I understand the Sylow theorems and can use them to show that there must be 24...

I think that I just noticed something that I probably should have noticed a lot earlier in my Abstract Algebra class: If G is a group which contains some g of finite order, then by definition g^k=e for some integer k. Does this mean that each element of finite order in G can be written as...

Find <nlm|(1/R)|nlm> for the hydrogen atom (nlm = 211), R is just the radial position Operator (X2 + Y2 + Z2)½.

Homework Statement The half life period of N-13 is 10.1 minute. Its life time is ------- The answer has been given as infinity. Could someone help the formula to arrive at this answer 2. The time taken by the radio active element to reduce 1/e times is ----- The answer has been given as...

Is the following property exclusive to the identity elements: a- = a (inverse of a = a)?

Hi, I'm reading Sean Carroll's text, ch2, and believe I understood most of the discussion on Integration in section 2.10. However in equation 2.96, he states that \epsilon\equiv\epsilon_{\mu_1\mu_2...\mu_n}dx^{\mu_1}\otimes dx^{\mu_2}\otimes...\otimes dx^{\mu_n}...

Homework Statement Calculate the general matrix element of the position operator in the basis of the eigenstates of the infinite square well. Homework Equations |\psi\rangle =\sqrt{\frac{2}{a}}\sin{\frac{n \pi x}{a}}...

Homework Statement I was looking through my notes, and I saw that my professor solved a propellor blade problem in a way that I don't understand. I took this class two semesters ago, so I cannot ask the professor himself. The problem that I am having is with his setup of a differential element...

Homework Statement Let {p_n}n>0 be the ordered sequence of primes. Show that there exists a unique element f in the ring R such that f(p_n) = p_n+1 for every n>0 and determine the family I_f of left inverses of f. Homework Equations The ring R is defined to be: The ring of all maps...

I need to construct a heating element powered by 9V that needs to reach 400 C. How do I figure out what length of wire I will need. I will most likely be using nichrome or kanthal A1

[b]1. Homework Statement [/] Is there a group G with order 100 such that it has no element of order 4? How would one go about proving the existence of such a group? [b]2. Homework Equations [/] For every prime divisor p of a group, there exists an element with order p. The...

Homework Statement I have just started solid state physics course and we got an assignment to choose one element that we are going to work with. Which element is interesting from a solid state physics point of view (and relatively not too difficult to work with)? Homework Equations...

So X, Y = non-empty sets, and f = function (X,Y) I have to show that f(A and B) (c underlined) f(A) and f(B) using element argument. I have no idea - started with choosing x as a particular but arbitrarily chosen element of f(A and B) so now I have to show it is in f(A) and f(B)...

Homework Statement A group <x> has order n. k= nq+r where 0<= r < n. Prove that the order of x^k is n/d where d = gcd (n,k) Homework Equations The Attempt at a Solution I know that (x^k)^(n/d) = 1, but how do I prove that n/d is the smallest one? I tried to assume that...

Homework Statement Let gcd(h,k)=1, o(a)=h, o(b)=k, show that o(ab)=hk Homework Equations o(a)= order of a modulo n o(a)=k iff k is smallest integer, a^k=1 mod n The Attempt at a Solution to prove o(ab) l hk, no problem, just need to show (ab)^{hk}=1 mod n and to prove hk l o(ab), use...

Salutations! I just want to make sure I am on the right track... Homework Statement Let G be a group. Prove that if every element in a group is equal to its own inverse, then G is abelian 2. The attempt at a solution Pick two elements a, b \in \thinspace G. By assumption, a =...