Explanation Definition and 955 Threads

My first question is whether the next paragraph is a correct summary, and then I have questions about the two shaky points mentioned in the summary. In "The Elegant Universe", Greene presents the division of energy of strings into the winding energy, the uniform vibrational energy, and ordinary...

In software maintenance, I have noticed that very few organizations and companies publish a precise well written Software Explanation Document to explain exactly and in a very well written way how thousand lines program work. It is amazing that of all the documents that are written, none of...

Hi, Can anybody please explain to me (in everyday language) what spectral index is? The wikipedia entry doesn't shed much light, and a lot of the textbooks give very convoluted explanations for its derivation. Thanks.

In very simple terms, (1) How is RMS Velocity determined?

1. How would a general relativist explain why an object falls towards the earth? 2. Is it correct to say that it is not the apple that falls towards the Earth but it is the Earth that accelerates towards the apple? Why is this ok to say?

Homework Statement This question refers to Griffiths E and M book. See the solution here http://www.physics.gatech.edu/academics/Classes/fall2005/3122/hw9solution.pdf I don't understand why they say the torque we exert is clockwise (I assume that means in the minus z direction). Homework...

Homework Statement Hi 1) I read the following article: http://pdg.lbl.gov/2005/reviews/passagerpp.pdf On page 12 of the .pdf there is a figure, figure 27.8, which shows how a charged particle deviates from it's path when scattered by the Coulomb force that comes from the nuclei of the matter...

The null result of the Michelson-Morley experiment led Lorentz to believe that the ether can never be detected because it distorts things in the direction that they move with respect to it. But from what I've read, Michelson himself explained the result by saying that the ether must somehow be...

Just curious. For some odd reason, I don't seem to get it.

Can someone please explain something too me. From what I understand our current calculations suggest the universe is between 11 and 20 some billion years old. Astronomers have measured the cosmos to be roughly 156 billion light years across, or 78 billion light years from the outermost...

1. How would a general relativist explain why an object falls towards the earth? 2. Is it correct to say that it is not the apple that falls towards the Earth but it is the Earth that accelerates towards the apple? Why is this ok to say? Is it because, in GR, there are no preferred...

Today in class we went over the single slit experiment, the aim of the lesson was to see that the greater the diffraction angle the lower the intensity. We then looked at a graph where it showed along the x-axis the angle of diffraction and up the y-axis the intensity. There was a decrease in...

Q 5 Match the column If net force on a system of particles is zero then Table 1 Table 2 a) acc. of COM p) constant b)momentum of COM q)zero c)velocity of COM...

Homework Statement http://img220.imageshack.us/img220/2813/graphmo4.jpg [/URL] Homework Equations Not necessary The Attempt at a Solution The answers that I have up there are correct, but I was wondering why graph 2 did not look something like this...

this isn't my explanation, but I was just wondering what others thought: "Einstein's special theory of relativity showed that an object can be of two different sizes for two different people and that they can perceive the time between two events to have different duratoins. His General...

I am currently reading A Brief History of Time and after reading chapter 7 there are still concepts which I do not understand. Hawking explains that particles go into black holes while antiparticles are thrown outwards into infinity. How and why does this happen? He also goes on to explain...

Hey, well recently I've found out at the late age of 17, that you can only fold a sheet of paper 7 times over, no matter how thin, or large the piece of paper is. Is there any scientific reasoning behind this? I can't think of anything??

what exactly is the cut-off ratio, in physical terms?

Explanation for "hydrophobic"? Hi, in chemistry class I was always wondering how materials can be hydrophobic. I understand that dipolar molecules such as water are hydrophil because they attract due to the dipole interaction, but why do they repell neutral molecules? What is the...

Hello, I'm reading through my textbook and it claims the explanation for the twins paradox is that the space-traveler must experience acceleration during his journey... but could it not be said that, relative to him, the rest of the universe is accelerating in the opposite direction?

Is there any simpler proof for Cramer's rule because I've been trying to understand it from this site and some of it I just don't get http://planetmath.org/encyclopedia/ProofOfCramersRule.html

folks, when i was small,the explanation for thunder,given to me was that when two clouds clash lightning is produced and due to the collision thunder is heard but now someone told me that thunder is caused when two clouds clash charges are neutralised and large amount of...

This isn't so much a question specifically as a point that came up in my mechanics class... so sorry if I'm posting it in the wrong place! In a basic mechanics class; we were finding the frictional force on a box by thinking about someone moving it by pulling an attached string. Someone in...

I am still in high school taking a Physics class and honestly the book the school gave us just shows you example problems. So I was wondering if you guys knew of any good Beginning Physics books that would be good and have a lot more explanation. All we have done so far is learned about...

I conducted a transformer efficiency experiment using a 240/110V double wound transformer, first with one heater connected in series then with two connected in parallell. What I don't understand is why when both (identical) heaters are connected current almost doubles on the primary side. Why...

Looking for a "mainstream" explanation for gamma gays and nuetron capture signatures. One of Elizabeth's homework problems got me to thinking: Now if Elizabeth is reading this thread, please note that the "correct" answer (in mainstream thinking today) is probably a). However...

Homework Statement There is a bike odometer that measures distance traveled for 27" wheels. So what heppens if you use it on a bike with 24" wheels? Will the odometer show the same, a larger or smaller distance traveled? Explain. Homework Equations The Attempt at a...

Basically I'm in a chapter about double and triple integration, integration using polar cordinates, etc... I'm not a big fan of my book and it's not very clear to me , so maybe anyone knows where i can find online good explanation of the subject and maybe more exercises. thank you

I don't have much of a math/physics background, undergraduate physics and calculus is where I stopped... yet I find theoretical physics extremely interesting. The recent online hype about the "E8 theory" only really discusses the fact that Lisi likes to surf and doesn't wear a pocket protector...

Hello, My name is Joe and I am a junior in high school. I am taking AP Calculus right now along with a basic physics class. I am very, very interested in the special and general theories of relativity, but I want to know the exact logic behind it. Right now, I don't really understand any of...

There's a simple explanation that wasn't covered in the last thread about this. Start off with an ideal incompressable fluid with no viscosity in a pipe. The flow rate in the pipe is fixed. The amount of mass per unit time moving past any cross section in the pipe is constant, otherwise mass...

Homework Statement What surface is represented by r . a = conts. that is described if a is a vector of constant magnitude and direction from the origin and r is the position vector to the point P(x1, x2, x3) on the surface? The Attempt at a Solution I know that the dot product of two...

Hello all, I was doing some reading on doubly differential cross-sections and was wondering what does this actually measure, in a physical sense. The way I see it, it looks like the differentiation of the incident angle of the scattering with respect to the reflected angle? Also, there's also...

Hello everyone, I have taken up on reading a mathematical statistics book and have gotten stuck on the moment-generating function. I tried using Wikipedia for a simpler explanation to no avail... I noticed it is used a lot in finding the mean & variance for all types of distributions. Can...

Homework Statement I just want to know how to proceed to get 1/s - s/(s^2+1) using partial fractions on the term 1/(s(s^2 − 1)) I know this is probably straight forward but I just don't get it. Thanks.

Hi guys, I have another weak problem here if you would care to help, please. I am trying to convert between the julian day and the gregorian date, and I found a eally good website:http://www.ortelius.de/kalender/calc_en.php The only problem is that when I run into the centennial cycle...

I was seeing a documentary on amphetamines the other day and I was looking for a biological explanation for the accelerated aging that was apparent in the drug victims' faces. http://en.wikipedia.org/wiki/Crystal_meth#Effects It doesn't list my observation on Wikipedia...

1. How would a general relativist explain why an object falls towards the earth? 2. Is it correct to say that it is not the apple that falls towards the Earth but it is the Earth that accelerates towards the apple? Why is this ok to say? Is it because, in GR, there are no preferred reference...

Hello, I need a comrehensive explanation of Aliasing? and its relation to filters... Thanks for the answers

Homework Statement Explain what is meant by the heat capacity at constant volume, CV, and the heat capacity at constant pressure, CP. How are these two properties related for an ideal gas? Why is CP generally greater than CV Homework Equations The Attempt at a Solution...

If LHC does not see SUSY-partners, of course, this null result would not falsify all SUSY theories, as some SUSY theories could still be realized in nature at a breaking scale some point above 1 TEV, but would a null result falsify SUSY theories that serve as an explanation for hierarchy of the...

hey from what i have been told , in an electric circuit , electrons only move at a few millimeters per sec but then, how can u produce energy kilometers away from these moving electrons ? i mean if we look on an atomic level , u have electrons moving very slowly at the beginning of the...

[[disclaimer: this is *not* a homework assignment]] In general relativity, the lowest non-vanishing multiple of gravitational radiation is generically the quadrupole: the monopole is forbidden by Birkhoff's theorem, and conservation of momentum is forbidden by conservation of momentum. I...

Hi could please let me know the Dirichlet's theorem(Complex analysis) ,statement atleast... as stated in John B Comway's book if possible ...I don't have the textbook and its urgent that's why...thank You

How can we be sure that the Cosmic Microwave Backgound Radiation is a relic of the big bang and not a reflected echo of the sun's solar wind after it's interaction with the heliopause? I ask this because I read an article some years ago which indicated that one of the voyagers had detected a...

Is the Sun heading towards a Maunder Minimum? [PLAIN]http://science.nasa.gov/headlines/y2006/10may_longrange.htm[/URL] The following is an excerpt from the above link: The sun's "Great Conveyor Belt" And from the next link, it appears there was a failed solar magnetic field...

i am having so much difficulty understanding lenz's law. i don't know what it means and how to use it. will someone please give me a good explanation for it because my book SUCKS and I'm having a very hard time understanding this hard(and stupid) topic so please help me.

I JUST started adding vectors.. as in.. last class. I got a ton of questions, and have done three of them. The answers are given, but I got them wrong. I'll follow the little template already given: Homework Statement What is the net force on a stack of books which are applied two forces...

I have done a little research on the internet and I would like to ask my concept is correct or not. 1) Sky is blue As the effect of rayleigh scattering is more effective for shorter wavelength, blue light scatter more than others (e.g. red). Furthermore, our eyes are more sensitive to blue...

Last month I asked here whether there's a consensus about Van Flandern's speculations about the speed of gravity. I quickly learned that he's not well-regarded. Fine. I was hoping to be able to get something out of Steve Carlip's explanation for how GR explains the apparent almost...