Element Definition and 836 Threads

Homework Statement Current flowing through an element is i(t)= 2e^(-t) and voltage across that conductor is v(t)= 2 (di/dt). Find out the charge is delivered to the element and power and energy consumed by the element in between 0 to 3 seconds. Homework Equations i(t) = dq/dt power =...

Homework Statement Prove that the additive inverse -v of an element v in a vector space is unique. Homework Equations Additive Inverse in V For each v in V, there is an element -v in V such that v + (-v) = 0. The Attempt at a Solution Assume that the additive inverse is not...

I've been searching around on Google for a place to buy a rare Earth element, specifically Thorium (.5 to 1 kilograms), and have been unsuccessful. Are there any sites that I can go to that would sell it, or has this type of commodity become unavailable to the average person due to possible...

Hi friends, Can you help me to seeing the meaning of the following pat from Gottfried's book on qm?to illustrate the failure of classical physics before the invention of quantum physics,he says--- "classical physics cannot explain why the properties of a sample of an element are identical to...

Hi I need a heating element, 5 cm x 5 cm, to heat up a chip. Temperature range 293 - 373 Kelvin Anyone know what to go for?

Homework Statement If G is a finite groups whose order is even, then there exists an element a in G whose order is 2. Homework Equations The Attempt at a Solution does this mean that a^2 is the identity? how can i prove this? Also, would't this make G cyclic?

[SIZE="3"]Suppose that p and q are odd primes and p=2q+1. Suppose that α∈ Z_p^*,α≢±1 mod p. Prove that α is primitive element modulo p if and only if α^q≡-1 mod q.

Say set p = \left\{p_1, p_2,\ldots,p_n\right\}, how to notate p_n without saying p_n, since I'm not explicitly writing out p like that for a variety of reasons? Like max(p) has the maximal element, what about last(p) or something? Is that recognized?

If you were to put 1 atom every element in its elemental form in a box, what would be the resulting compounds? 1.) I know it's probably impossible. 2.) I don't mean highly radioactive elements (transuranium metals, francium, radon, astatine, etc.) 3.) I'm really only talking about some of...

Homework Statement Compute the area element for elliptic cylinder coordinates Homework Equations The coordinates are defined as follows: x=a*cosh(u)*cos(v) y=a*sinh(u)*sin(v) The Attempt at a Solution Starting from the assumption that the area element dA=dx*dy, I found dx and dy...

Regarding a 12v source, is there a way to calculate how much energy is required to maintain a certain temperature through an element? Meaning if you want to maintain an element temperature of 35 F how much energy will it consume using 12v? How will the ambient temperature affect this equation...

Homework Statement this is part of a theorem for the error estimate for the model problem for finite element method. i have to prove the following inequality: \left|u'(x)-\tilde{u}'_h(x)\right|\leq max_{0\leq(y)\leq1}\left|u''(y)\right| Homework Equations \tilde{u_h} is the...

Homework Statement Let R and Q be the groups of real and rational numbers under addition, and R/Q be a quotient group (or factor group). Part a) If a + Q = b + Q for a,b ∈ R, what can you deduce about a and b? Part b) Prove that every element in R/Q has order 1 or ∞. Homework...

Homework Statement If G is a finite group and g is in G, then there exists a positive integer r with g^r=e. and in general, prove that, in any finite group G, the inverse of each element is a power of itself. Homework Equations The Attempt at a Solution I know if a group is...

Consider a beam under combined loading. Axial force, bending moment and torsion. I'm interested in determining the principle stress in any stress element on surface of beam. Well as per rule I've to show my attempt so: normal stress=axial load/beam crosssection shear...

Hello, I was just reading about implicit vs explicit finite element solvers and have a question about the difference between them. I understand that the implicit solver has a linear approximation step that is used to force equilibrium. My question is does that make the explicit solver...

Homework Statement using only trigonometric identities, derive the differential area element in polar coordinates? any help with this problem or at least a start? Homework Equations i found this so far dA=(dr)(rd θ) The Attempt at a Solution i have tried to figure this one out...

Homework Statement Given that the current flow is due to electron flow, state whether electrons are entering or leaving terminal 2. i _____ --> | | - -----|1 | v | | + -----|2 | |___| Situation A: V=40V, i=-10A Situation B: V=-60V, i=-10A Homework...

I am trying to make a program that solves elasticity problems with finite element method and I don't understand how to bring in boundary conditions. Constant displacement boundary conditions seem simple: replace variables that represent the displacements at surface nodes with the prescribed...

http://users.on.net/~rohanlal/MOHR.JPG For this I-Beam which has a depth of 50mm I need to determine the Principal and maximum shear stresses acting on an element mid way between the Neutral Axis and the top of the flange (12.5mm from the top of the flange). I don't know how to determine...

For a set S, there is an identity element e with respect to operation * such that for an element a in S: a*e = e*a = a. For a matrix B that is m x n, the identity element for matrix multiplication e = I should satisfy IB = BI = B. But for IB, I is m x m, whereas for BI, I is n x n. Doesn't...

Is it possible create a quantum mechanics simulation to predict what the half life of an element will be, say C-14? I know one way to figure an element's half life is to get a bunch of atoms(a really big number of them), wait for some time to pass, and count how many atoms decayed, thus the...

Homework Statement Hi guys, i need a bit of help with the following question. Ok the question states the following, explain why the element of charge, dq, located within an infinitesimally thin spherical shell or radius r is equal to rho(r)*4*pi*(r)^2dr, where dr is the thickness of the...

According to Webelements.com, http://www.webelements.com/nexus/node/1419 I bet people will call it Copernicum, just like we say aluminum in the US as opposed to aluminium (UK, Australia, NZ, etc).

I need to prove that if a group contains exactly one element with order 2, then that element is the center of the group. Here is how I formulated the problem: Let A be a group with an element c such that c^2 = 1 (i.e. c = c^-1), and b^2 = 1 implies b=c. Want either: ac = ca, for all a in...

May anyone help me on how to define the units used to define the abundance of elements on Earth's crust "It's written ppb(parts per billion by weight)" I really fail to define that!

Homework Statement Let G be a group of order 2n. Show that G contains an element of order 2. If n is odd and G is abelian, then there is only one element of order 2 Homework Equations Theorem (Lagrange): If H is a subgroup of a group G, then |G|=[G:H]|H|. In particular, if G is finite...

Homework Statement In the 7 diagrams below, the solid arrow represents the object and the dashed arrow the image. The rectangle shows the position of an SINGLE OPTICAL ELEMENT. Match each diagram with the appropriate optical element. 1)http://img190.imageshack.us/img190/5176/92585723.gif...

only one isotope of element X occurs in nature. One atom of this isotope has a mass of 9.123x10-23g. What is the molar of the element X?

Hey ppl i wanted to know that wat is the name of the method with which astrosphysicists are able to detect the elements present in supernovae.for eg they say type 2 suprnva is mainly hydrogen containing. Is it by spectroscopy if yes which one? pleasez temme soon

Let's say I have an unsorted array of integers. Is it possible to determine if there exists a number in the array that appears only once with a time complexity of less than O(nlogn)? Sorting the array takes nlogn time so I'm wondering if it's possible without sorting. I don't need to return...

If I have a semigroup S, is it possible to partition the set of element S into two semigroups S_1 and S_2 (with S_1 \cap S_2 = 0), in such a way that S_1 has an identity element but S_2 has none?

Hello I have an assignemt to analysis a landing gear for the cyclone earoplane, an initial design being supplied, I have being askedto check for the suitability of the part, the conditions are: Aircraft mass with fuel: 43000 lbs Landing speed: 65 Knots Maximum deceleration: 3g Each part...

Can a set A be an element of A, or can A be not an element of A? And what would such mean in plain-speak?

For two level system , let denotes the ground state as 1 and exctied state as 2, for writing the office off-diagonal matrix element for the density operator, shall it be \rho_{12} = |2\rangle\langle 1| and \rho_{21} = |1\rangle\langle 2| ?

Homework Statement Let \vec{F} = xy\vec{i} + yz\vec{j} + xz\vec{k} and C is the boundary of S, the surface z = 9 - x2 for 0 ≤ x ≤ 3 and -6 ≤ y ≤ 6, oriented upward. Use Stokes' Theorem to find [tex] \int\limits_c \vec{F} \cdot d\vec{r}. Homework Equations The Attempt at a Solution well...

Homework Statement An unknown nucleus contains 71 neutrons and has twice the volume of the nickel http://www.webassign.net/www32/symImages/f/1/3dca243bf11d1adbce4ca198d1973f.gif nucleus. Identify the unknown nucleus. Homework Equations r = (1.2X10^-15)(A^(1/3)) V= (4/3)(pi)(r)^3...

Everyone, I am a Mechanical Engineer working on a design modification (or existing product recommendation) for an Idaho National Laboratory project. What follows is the situation description. At the end is the question. You can skip down to the bottom of the post (which details the...

Hi, Does anyone know where I can get any programming for finite element in 3d object not calculation but for the display such as cad (e.g. meshing display)? Also what software that can do above operation? I mean, not ansys, nastran, algor, etc., but other that I can make it by myself by my...

Homework Statement 3Ag2 S + 2Al --> 6Ag + Al2 S3 consider the equation for silver tarnishing. a) state the oxidation number for each element in the reaction. b)identify the the oxidized reactant and the reduced reactant. The Attempt at a Solution Ag2=2 S= -2 Al=0 --->...

As I understand it, Uranium is the heaviest "natural" element that is still observable on Earth because of it's stability, but what is the heaviest element that may have ever been produced by a supernova regardless of stability?

Hey guys I'm dissecting this pencil sharpener to see how it works. I understand every component except one. The sharpener is battery operated, running on 4 AA's and once the current leaves the battery you can trace the wire to a small platform containing two elements connected. The first element...

what is the percentage of heavy element (heavier than helium) of the sun? (not the photospheric composition)

how the decay depends on total mass of the radioactive element? is it necessary that all the atoms of the element keep contact among them, for the above case?

Homework Statement A heater consists of heating elements connected in parallel across a power supply. A wire in one of the heating elements breaks. What happens to the total resistance of the heater? And the power output of the heater? The Attempt at a Solution Will the resistance...

I am looking for a 4D angular coordinate system (radius and three angles) and its corresponding "hypervolume element". 2D: polar coordinates - dA = r dr dtheta 3D: spherical coordinates - dV = r^2 sin(phi) dphi dtheta dr 4D: ?

Hello, I was thinking about how to predict the order of an element a*b if the orders of a and b are known where a and b are elements of some group. One textbook I have gives the result (without proof) that if a and b commute and their orders are relatively prime, then order(a*b) =...

hi, in MatLab, if you have x and y vectors and want to address an element in vector x, let's say i>=3 from which to construct a new vector x that starts from the addressed element until the last element and at the same time construct a new y vector corresponding to the new x vector? x=[1 2 3...

In Ray d'Inverno's book on general relativity, he defines the volume element in a way which makes it a scalar density of weight -1, meaning it transforms with the inverse of the Jacobian. Every other source I have looked at seems to say it should transform with the Jacobian, making it a scalar...

Homework Statement Show that (S, *) is a group where S is the set of all real numbers except for -1. Define * on S by a*b=a+b+ab The Attempt at a Solution Well I know that i have to follow the axioms to prove this. So I started with G1 which is associativity. This one I got to...