Element Definition and 836 Threads

Hi, I was just reading up on some astrophysics and I saw the line element (general relativity stuff) written in spherical coordinates as: ds^2 = dr^2 + r^2(d\theta^2 + \sin\theta\d\phi) I don't get this. dr is the distance from origo to the given point, so why isn't ds^2 = dr^2 without...

Can someone help me on where to begin? What do I know about even ordered groups that could help? My first idea was to incorporate the fact that for an element to be of order 2, it must be it's own inverse. (This made me think of the identity element- I don't know if that's what the proof...

I wanted to get some thought in non linear fea. Let me say there is a spring of initial stiffness k. Let me say in a non linear analysis the load is divided into 20 steps of 1N each(Total load is 20N). 1.1st iteration.1N is applied and the displacement is arrived 2.2nd iteration 2N is...

We can say that the macro properties are emergent properties (non existent at the previous level of complexity, that of atoms) dependent also (apart the quantum laws) on the complex arrangements of the elements at the 'lower' structural level. In the case of many such emergent properties (such...

What, in the atom, dictate elemental properties? I know that protons dictate different elements, but what part of an atom determines if it's a solid, gas, liquid, black, gold, or anything?

how can we fnd out the half life of sum element?

How to determine the matrix representation of position & momentum operator using the energy eigenstates as a basis

what is a non linear finite element finite element analysis. When does a structure behave non linearly and how do we calculate non linearity of an element by the nodal displacements.

Suppose I have a set involving trigonometric functions, with addition defined as multiplication of two vectors. If this is a vector space, the zero vector has to be unique. If cos (0) works as the zero vector, then cos (2*pi), etc. also work. Does this mean the set is not a vector space...

i know that the stiffness for a line element is calculated as fl/ae where a is known as area and l is the length,f is the force applied and e is the youngs modulus. How the stiffness of a plate element are calculated?

How is it that with taking coefficients over a "simpler" ring, we are able to recover more information about the homology of a space? For example, if we take the projective plane as the union of a mobius band and the 2-disk glued along their boundaries, with coefficients in R we only get...

Hello all, I've been trying to model a plate under uniform tension using FEA techniques (in ANSYS). The plate has a circular hole in the centre, and has two axes of symmetry so I've created a mesh based upon the 'top right' quarter of the plate. I'm pretty sure I've done everything right...

If I'm writing a proof that depends upon the assumption that a set of unique identifiers (integers, names, etc) must have a "greatest" element under some ordering scheme, what do I need in order to be entitled to make that assertion?

In "Do we really understand quantum mechanics? Strange correlations, paradoxes and theorems." by F. Laloe, Laboratoire de Physique de l'ENS, LKB, 24 rue Lhomond, F-75005 Paris, France, Laloe explores the meaning of "element of reality": "3.2 Of peas, pods and genes When a physicist...

What would be an example of an element that is also a molecule? Would hydrogen be an example of this?

As the temperature increases and pressure remaining constant. Does the half-life of a radioactive element stay the same? Also, Which gaseous radioactive waste product that is released into the atmosphere after it has decayed to a safe radiation level? radon-222, radium-226, cesium-137...

My school textbook says that "The decay of a radioactive element is a random process and does not depend on external factors such as temperature". But if the decay is a random process, how can we accuratley predict the amount of substance after t seconds using the rate law?? Did I miss something?

I have modelling a mechanical element in ANSYS. Those who have used it will know what I am talking about. I want to obtain the reaction forces at the supports (Fx,Fy,Fz,Mx,My,Mz). So I go to List Reaction forces command window and Ansys gives me a list of nodes and its single reaction: PRINT...

Hi. I'm having a hard time solving this problem. I have to find the identity of element X in the following reaction: XCl_2~+~Cl_2~-->~XCl_4 knowing that 10 grams of XCl_2 + 2.55 grams of Cl_2 produces 12.55 grams of XCl_4. Now, I thought about doing mass percent composition that...

finite element analysis alternative?? hi do you happen to know any alternative for using Finite Element Analysis(FEA)? i need to know it badly.. hope someone could help. thanks!

From the information below identify element x: A. The wavelength of the radio waves sent by an FM station brodcasting at 97.1 MHz is 30 million times greater than the wavelength corresponding to the energy difference between a particular excited state of the hydrogen atom and the ground...

What is meant by 'weather element" What is meant by 'weather element"

physics element in "october sky" hi, my physics teacher gave us a project, we watched "October Sky" in class, and the teacher wants us to do a two page report on the "physics element" of october sky, one of the most prominent moment with the most physics presented is when Homer trys to prove to...

Can someone give me a very good website to learn FEM ? :blushing:

Vector A has x and y components of -8.40 cm and 16.0 cm, respectively; vector B has x and y components of 12.6 cm and -6.00 cm, respectively. If A - B + 3C = 0, what are the components of C? Not sure how to do this problem, I was thinking of adding the horizontal and vertical elements for A...

relative atomic mass of an element ? A sample of neon was found to cotain 90.9% of 20Ne, 0.26% of 21Ne, & 8.8% of 22Ne, Calculate the relative atomic mass of neon. this is what i'v done so far (90.9x 20)+ (0.26x21)+(8.8x22)= 2017/? i don't know what to divide it by :confused: ? I'm not...

So I'm fiddling about with formulae...trying things out...consolidating...as you do...and something didn't work - why? The infinitesimal area element in polar coordinates dA = r*d(theta)*dr . Agreed? Now in the same coordinate system x = r \cos{\theta} ; y = r \sin{\theta} . Taking...

I'm confused by something my book says. For reference, here is the relevant text: Figure 18-5b shows an oscillating element of air of cross-sectional area A and thickness \Delta x, with its center displaced from its equilibrium position by a distance s. From Eq. 18-2 we can write, for the...

Element properties?? I needed some help with the following problem. I don't know what the question is asking me to do. Breafly account for the following relative values: a.) The melting point of sodium is 89oC, whereas that of potassium is 63oC

I have recently read that the platinum family transition elements (copper, gold, iridium, etc) have unusual properties when reduced to the monoatomic state. Basically, high spin leading to nucleonic deformity causing an extension of the shielding potential over the electron shells (valence...

8. [CJ6 14.P.001.] A mass of 135 g of an element is known to contain 30.1 1023 atoms. What is the element? carbon hydrogen oxyden aluminum This is the question on my Physics practice test for my exam tomorrow. i don't know where to even begin with this one. we haven't really gone over...

Does Mercury have properties that would permit its' use as a Fuel to power Spacecraft? Has this been done before or experimented with? If it is heated to its' vaporization point, what happens? I know it is highly poisonous but I have heard that it has a potential for use as "a" fuel.

Do scientists know how many electrons an element has? Can someone explain why I was taught about shells of electrons in atoms?

http://www.delteria.net/images/calctest.gif Conditions: a. f'(x)=0 b. f"(x)= 0 c. f'(x) = DNE d. f = relative max e. f = point of inflection What I have so far (they can repeat I believe): a. X0, X4 b. X3 c. X1 d. X2 e. X2 I'm sure something is wrong... Also, what would a...

Would a heating element have a very high resistance, or a very low resistance? (All comments in this post are based around the fact that the voltage is the same for each situation) I would have thought that a higher resistance would have resulted in more heat loss, but I've been taught that the...

Chemistry help please! I took Chem. 2 yrs ago, don't remember much from it. Next yr, I'm planning to take AP Chem. so I have to do Summer HW. I know that H is the symbol of Hydrogen, C is Carbon.Can someone please help me how to figure out how to write element symbol, for example how to write...