Section Definition and 680 Threads

I need to classify the conic given by the following equation: x^2 + xy + 4y^2 + 3x - 9 = 0 I found A = \left(\begin{array}{cc}1 & \frac{1}{2}\\\frac{1}{2} & 4\end{array}\right) I need to find an orthogonal matrix P with detP = 1. So I find the eigenvalues of A I get (\lambda -...

What is the cross section of a photon traversing the observable universe? That of a neutrino? Dark matter in general?

Sorry guys, I thought it would be easy, but it is not. I have a random quadrilateral A,B,C,D, drawn and a random point M inside of it. Now, I want to draw a line passing through the point M and crossing the sides AB and DC at points P and Q. So far so good, but I want more, in addition...

(I am not sure whether I'm posting in the right forum. I apologize if I do) Does anyone have an alrorithm or a code (in any language) that constructs a Poincare surface of section? I want to do so for a Hamiltonian model: A mass under the influense of the Henon-Heiles potential. It has to...

I have no idea which forum this question should go in, so feel free to move it, mods. But I am looking at an astronomy paper containing this symbol, so I'll ask here. What is that symbol that is used to mean "section"? For example: "The relative light curves of XN Mus 1991 were derived...

Calculating Surface area/volume from 2D cross section?? I'm feeling a little stupid today and I need some help...:-p Assume that I have a radially-symmetric 3D object (for example a candle stick or the base of a table lamp) and that I can calculate the surface area of the largest longitudinal...

ok I am in consepual physics 7th edition by paul g hewit and the sound section makes no sense... It is really badly written ie it tells about media storage but not about sound... ok here is my problem: chapter 18 it says that speed of a wave = frequency * wavelength chapter 19 it says...

I've been told that this thread should have been in this section. https://www.physicsforums.com/showthread.php?t=101782" Sorry about that. EDIT: HERE IS THE TEXT This is mind boggling. There is an array of 16 squares, arranged in a 4 x 4 grid. A supply of 4 A's, B's, C's, and D's are given...

What is "momentum transfer cross section" ? Hi all, I'm reading a book on electron-molecule interactions and I'm puzzled by a quantity (well, by the difference in definition of two quantities). The book is, for your information, "fundamental electron interactions with plasma processing gases"...

Can we create a section on physicsforum.com dedicated to the different mathematics software? Separate forums for Maple, MatLab, and Mathematica would allow us to group together questions on those different software packages.

I got the first part of this question but can't seem to get the 2nd part.. A 105 V potential difference is applied to a space heater that dissipates 1000 W during operation. (a) What is its resistance during operation? 11.025 OHM (b) At what rate do electrons flow through any...

I have read about "Thompson Cross section for free electrons" My problem is there must be the other cross sections photons are scattered by free electrons. photons must be scattered by aka protons and as well by alpha particles. Is there any defined cross sctions for the other particles as...

In this section explaining relativity, " If a mirror clock and a conventional clock in the spacecraft agree with each other on the ground but not when in flight, the disagreement between them could be used to find the speed of the spacecraft independently of anyh outside frame of...

In the book "Gauge Theories of the strong, weak, and electromagnetic interactions" by Chris Quigg the calculus of the scattering of proton-electron is esbosed (chapter 7, section 3 , pag 168). He get the result (in the lab frame): \frac{\mbox d^2\sigma}{\mbox d E^\prime\mbox...

Does anybody know where to get the expected cross section for Z at the LHC (pp at 14 TeV)? (it would be great if you could provide a reference).

In this problem, you will estimate the cross section for an earth-asteroid collision. In all that follows, assume that the Earth is fixed in space and that the radius of the asteroid is much less than the radius R of the earth. The mass of the Earth is M_e, and the mass of the asteroid is m. Use...

I'm going through my intro to mechanical engineering material and there was one thing I was never clear on: If you have a cross section of a rod, why isn't its' area at a cross section pi * r^2 as a opposed to piD^2/4, where D is the diameter?

Is anyone familiar with Breit-Wigner Cross section? Say, for a reaction with 2 particles in the initial state, 1 intermediate and 2 final: \sigma = \frac{g \pi \lambda^2 \Gamma_i \Gamma_f}{(E-E_0)^2 + \frac{\Gamma^2}{4}} I can't see why for the wavelength we should use the momentum of...

I'm looking either for online resources or reference to a good book. I've been trying to help someone with a homework problem in a course entitled, Elements of Mechanical Design which uses Mechanical Design of Machine Elements and Machines by Jack A. Collins. The book sucks. The system...

How do I find the volume of a bowl shaped section of a sphere, given the depth of the section. I know i can integrate it, but a friend says that i can find the volume of a cone with equal height and radius, and then use that to find the volume of the spherical section.

What is the differential cross section for photo-electric effect? Is there a paper that explains this in more detail? Thanks in advance for any responses!

Hey...i'm about to take the PSATs in a week...any tricks w. the math aspect? I'm in calc...so i figure that'll help thx pat

Hello People! Im new to this forums and didnt really found a specific thread on Latex help. Im trying to convert word documents into Latex format. Im a novice in this topic.. was wondering if anyone can help me out. I have a problem in changing the default value of Section in Latex...

Area moment of inertia--circular cross section From the bending beam calculation, the moment of inertia of the cross section with regard to a coplanor axis of rotation is used. If we have a circular "beam", the area moment of inertia of a circular disk of radius a about a diameter is I_d =...

The question is: 19.5.4 Show that the s-wave phase shift for a square well of depth V0 and range r0 is δ0 = -k r0 + tan-1{(k/k') tan(k'r0)} where k' and k are the wave numbers inside and outside the well. For k small, kr0 is some small number and we ignore it. Let us see what happens...

I have a major problem. Let me explain everything from the beginning. I got a 120 GB HD and decided to partition it to three section. One section had about 80 GB w/o an OS. The second was 20 GB with XP Home and the third 10 GB with XP Professional. Therefore, while booting, the computer will ask...

Can someone explain what absorption cross section is and how it's figured into an equation? And what is irradiation?

If the area enclosed by an ellipse 4x^2+y^2=1 and its cross section is perpendicular to the x-axis then its volume is? I don't have the slightest clue how to do this? Maybe solve for 2y^2=1-4x^2 set the integral equal to pi times the intergral of 1/4 to 1 of 1-4x^2?

Here is a problem don't understand: A liquid with a density of 1.08*10^3 kg/m^3 flows through two horizontal sections of tubing joined to the end. In the first section the cross sectional areais 10.5 cm^2, the flow speed is 274 cm/s, and the pressure is 1.29*10^5 Pa. In the second section, the...

If anybody else has had problems with Rise of Nations can you please refer to my post in the Software section.