Elements Definition and 984 Threads

Homework Statement PROVE: If A(t) is nxn with elements which are differentiable functions of t Then: \frac{d}{dt}(det(A))=\sumdet(Ai(t)) where Ai(t) is found by differentiating the ith row only. Homework Equations I know I should prove this by induction on n The Attempt at a...

A massive star collapses when it begins to create iron in the normal fusion sequence. Iron absorbs energy. The collapse then produces all the heavier elements. When the heavier elements are created is energy absorbed or released?

what is basic principle followed by atoms to arrange in basic structure?

Is there a way of calculating the field of elements in a system using the base? I expect that's the main way, I am just unlearned. For Example base phi: (1+√5)/2 has the FoE Q[√5] = Q + [√5]Q Is it just any non-rational elements are added to the field? what would base: (√2 / √7) be?

Replacing specific array elements in IDL - solved! Hi I was just wondering if there was any way, other than using FOR loops, to replace specified elements of an array? For example, say A is a 1D array of 50 elements, each equal to 1.0. Is it possible to change say elements 0-9 and 30-49...

in line integrals we always need a vector element of distance. I can't understand the difference between ds and dr. is ds for all kinds of paths (even curly ones) and dr only for straight lines, or theyre the same? I am confused, or maybe dr is just the magnitude of ds, and the vector here is...

I just want to know, what are the essential elements of being a mathematician? Because I want to decide whether I am better to study physics or mathematics in the University. I knew that a lots of people learn mathematic olympiads and got a good result in the competition...

Hi The following structure has 2 elements. people = struct(... 'name',{'bob', 'john'},... 'numKids',{0, 2}, ... 'kidsage',{[],[12,9]}); each element people(1), people(2) has three frields (name, numKids, kidsage) Instead of declaring the structure in one line as above...

I have a vector, say v = [ 1 2 3 4 5 6 ...] ' and suppose that I want to first take the first n elements and place them somewhere else, then the next n-1 elements and place them somewhere else, and so on... How would I do the indexing if it were performed in a loop? So for example, if v = [ 1...

http://i111.photobucket.com/albums/n149/camarolt4z28/IMG_20110804_134032.jpg?t=1312484230 http://i111.photobucket.com/albums/n149/camarolt4z28/IMG_20110804_134038.jpg?t=1312484242 I found that the order of G/H is 6. According to the Lagrange's Thereom, order of G = order of H *...

Why do certain elements (particularly transition metals) possesses varying charges in different reactions? For example: Iron (Fe), is known to exist as Iron2+ and 3+.

I have a nested list of the type: {{1, 2, 3}, {1, 2, 4}, {1, 1, 2}} I want to find the number of sublists in which the first two elements are equal, so in this case that's one (the sublist {1, 1, 2}). Is this possible in Mathematica?

Can we describe describe n such that Z_n has exactly 12 invertible elements? Thank you

Is it possible that even in a vacuum that the void space in the vacuum could consist of some other material? What is the median on which gases move, what is the nothingness in between atoms?

Hello all, I have a question concerning the best way to access random elements in a large file. I have a single data file of numbers, 12G in size with dimensions 1024x768x16384. My goal is to, as quickly as possible, load, say 16384 of those numbers into memory. Assume these numbers are not...

Between Sulfur and Iodine, which has more Electronegativity? I read that they both have the same, if so how can i determine in SI2 compound around which atom do the shared electrons spend more with with(Since that is determined by which atom has greater electronegativity) Or maybe they spend...

Hi everyone, I've been banging my head against this problem for a few days now so I'm ready to find some help with it. In short, I have a set of orbital state vectors(a position vector and velocity vector) describing an object's starting position, as well as the mass of the focus, and I...

Homework Statement How many elements of order 2 does the symmetric group S_4 contain? Homework Equations The Attempt at a Solution I know that transpositions have order two. Moreover, any k-cycle has order k. Thus there are six elements with order two contained in S_4? Is this...

Apologies, the LaTeX thing doesn't seem to be working, so not very clear! I am working through a book on representation theory, but am stuck on these exercises. Homework Statement Let G be a finite group and let E = Sum g (running over all g in G). (i) Prove: Ex = E (forall x in G)...

Homework Statement Find I1,I2,I3,Uc Homework Equations I was trying to make this task but my result was not correct Before commutation I=E/(R1+R2)=0.1 A U=0.1*R2=100 V After commutation I=0 A In the moment equatations I1*R1+I1*R2-I3*R2=E I3*R2-I1*R2=Uc I3=C*dUc/dt But when I had got result...

i hope I am asking this at the right place i just have a few questions... why does it take so much power (115v) to heat up a small coil(heating element) roughly the size of a spring in a pen. what could get just as hot, maybe a resistor? i have a 18 volt battery from a drill and i need to get...

Homework Statement Write out the following sets by listing their elements between the curly braces. a. 2^\emptyset b. {x:x \subseteq {1,2,3,4,5} and |x| \leq 1 The Attempt at a Solution a. I'm not sure if the only element is one, or if this is an undefined operation. b. I think the...

i am a 3rd year engineering student currently a course in computer methods for structural analysis, as a part of the course we are learning about finite elemnts, we have learned about CST LST Q4 and Q8, but i am having difficulty deciding which element to use for different models. does anyone...

Homework Statement Let G be a finite abelian group, and assume that |G| is odd. Show that every element of G is a square. The Attempt at a Solution So we want to show that \forall g \in G, \exists h \in G, g = h^2 . Let g \in G be arbitary, and consider the subgroup generated by g, denoted...

Ok, so all elements undergo radioactive decay. But why? I have been snooping around and what i find is that radioactive decay occurs because of instability of the atom nucleus in quantity, proton-neutron ratio and energy content; therefore we have alpha, beta and gamma decay consecutively...

Hello, I would like to ask if elements of higher atomic number than iron might actually be clusters made up of smaller elements? Is there any evidence that rules out this possibility? The reason I am guessing that elements below iron are discrete is because of the theory that iron has its...

Hi, I have a question about comparing each and every element in a matrix.. Heres what i have, S1 = 90 S2 = 1 delta = 0.75 SM = 80 m = 0.1:0.01:100; if (S1-S2*m.^(delta))>=SM S_avg = SM elseif (S1-S2*m.^(delta))<SM & (S1-S2*m.^(delta))>0 S_avg = (S1-S2*m.^(delta)) else S_avg = 0...

what will result when 6th group elements are used as dopants to silicon ?

In my lecture notes the symmetry elements for XeF4 are listed as: [PLAIN]http://img690.imageshack.us/img690/7216/syms.png but nowhere does it explain what 2C2 or σh means. What are these symmetry operations?

This may be obvious but since the packing fraction for both hexagonal close packed and face centered cubic is the same (74% i believe) why is HCP more common in elemental compositions?

1. Homework Statement Remember, the set of groups (Gn, *), the group of multiplicatively-invertible elements of Z/n under multiplication. For p a prime, the elements of Gp are all elements of Z/p except 0; for n not a prime, the elements of Gn are all the elements of Z/n except 0 and those...

Hi All! This is my first time putting up my own thread on MF. I can usually find what I'm looking for, but this time: no go. As the title says, I'm trying to find the normalization constant of this 4x4 matrix (g and f are functions): (1-g^2) 0 0 0 0 (1+f^2)...

Hi everyone, :smile: I was wondering why they only use 5th and 3rd groups elements to create n-type and p-type semiconductors respectively. Couldn't we mix 6th or 2nd groups' elements instead to make the semiconductors? What would happen if we do this? Perhaps elements of those groups will...

Hi All, does anyone know of a mathematica function that efficiently circularly shifts all array elements? e.g. {1,2,3,4,5} -> {4,5,1,2,3} without iterating? The reason I ask is because I have a huge data set I'm working with and right now iterating through is very processing intensive...

I have run into a problem where I have a frieze pattern F, the frieze pattern has horizontal refelctive symmetry, glide reflective symmetry, but does not have 180 degree rotation and does not have vertical reflective symmetry. G represents the symmetry group for F. G={reflection symmetry...

Hi, I have been using both ANSYS APDL and ANSYS Workbench (Mechanical) to run analysis on a structure. After loading the structure, in Mechanical i was able to scope my results for deformation and EQUIV stress to just the adhesive layer as this is what I am interested in. However, I can't...

Hello all: I'm new to the world of finite elements/finite differences. I'd like to understand the advantages of the finite element method. I read that the finite difference method cannot handle complex (e.g., curved domains, fractures) geometries. I have had no luck in understanding why...

If I have a list say li = {18, 22, 4, 10} and I want to add for example 7 to this list Join[li, {7}] to get {18, 22, 4, 10, 7}, can I insert the 7 after the 4, to get {18, 22, 4, 7, 10}, I can't just use Sort[ {18, 22, 5, 10, 7}] as I don' t want to change the order of the whole list?

Homework Statement Let G be a group and let a be an element in G. Show that a and a-1 generate the same cyclic subgroup <a> = <a-1> and have the same order o(a) = o(a-1). Homework Equations This is in the second section of the book I'm using, so there aren't really any theorems that...

hey everyone i hope to find the answer to my troubles here :) basically i have written a gravity simulator, it loads bodies from a file containing information on each body. using the orbital elements on each body taken from nasa's HORIZON system, i calculate the position and velocity of...

Homework Statement The voltages across two circuit elements in series is zero. Is it possible that the voltages across the individual elements are nevertheless not zero? Give an example. Homework Equations NA The Attempt at a Solution I am not really sure where to start with this problem...

I saw this question in an abstract algebra text that I was reading. "Is it true that (w − x) − (y − z) = (w − y) − (x − z) is an identity for real numbers? Can you say why or why not?" I know that an identity element does not change the value of a real number. So 0 is the identity element...

Like, maybe transmutate certain elements into rare metals that we have a very limited supply of? By "all of the Sun's" energy, I mean an amount of energy similar to the amount we could collect from solar panels if we covered the Earth with solar panels (obviously that isn't feasible, but we...

Hi: In the case of a finite-dimensional normed space V, it is relatively-straightforward to show that the kernel of any element of V* has 1 . ( Assume DimV=n): We take a linear map L:V-->F ; F the base field. We choose a basis to represent L, then we consider F as a vector...

Homework Statement Let G be a smooth Lie group with Lie algebra \mathfrak g . Consider a curve X: [t_0,t_1] \to G whose dynamics are given by \frac{dX}{dt}(t) = H X(t) for some H \in \mathfrak g . Show that this equation is well defined for all time. The Attempt at a Solution Okay, so...

Hey, So I'm trying to figure out how the matrix representatives of Lie-algebras can act as derivations. In particular, let N \in \mathbb N and consider the Lie group of special unitary matrices \mathfrak{SU}(N). Now we know that the Lie-algebra is the set of skew-Hermitian matrices...

I believe this is the correct place to post this as I believe I'm going to need to solve this as a linear system, however I suppose it might be solvable using trig as well. However, I've been at it for a while and I'm out of ideas and I think I'm missing something silly. Consider the...

What are the main contributions to the matrix elements (intensity asymmetries with respect to normal emission) in ARPES? Is there a theoretical paper on that?

• Can we create any of the periodic table elements? • Can we make it cost efficient in the future? • Can we synthesis H20 in the laboratory?

Homework Statement Hi, i need to show how many elements there are in the group u={B in B : det(B)=1} where B is the group of invertible matrices - B = b(ij) in GLn(Fp) where Fp is a field with p elements. Homework Equations The Attempt at a Solution I know Fp^n has p^n elements...