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### Physics FAQ

Quality answers to common physics questions
May25-09 11:31 AM ZapperZ

# General Physics

- Nature and properties of matter and energy. For any physics topics not applicable to the categories below.
 Views: 584 Announcement: End of year contest, $75+$50 prize! Dec18-13 Meta Thread / Thread Starter Last Post Replies Views Pinned: Recent Noteworthy Physics Papers ( 1 2 3 ... Last) The aim of this thread is to highlight recent (as in within the past 3 months) noteworthy physics papers that have... Dec9-13 04:47 AM Cthugha 162 151,678 Before posting anything, please review the Physics Forums Global Guidelines. If you are seeking help with a... Apr22-11 06:27 AM ZapperZ 2 60,606 hi this is not physics homework I really need to find out the natural frequency of a window size glass so that I can... Feb5-05 04:09 PM Gonzolo 4 8,651 Are we as baryonic matter permeated by the ZPE, or do" solid", objects displace it? Feb5-05 07:41 AM wolram 0 783 Hi, can someone please explain to me what resistants is affected by in a wire and also what temperature has to do with... Feb4-05 05:19 PM GumzyG 2 831 Suppose I have an arbitrary amount of diode lasers, all of identical construction and abilities. Assume I can... Feb4-05 10:32 AM Laser Jock 17 13,572 What are the properties of materials havind negative refractive index? Are they theoretical or do they exist? Feb4-05 09:48 AM Gonzolo 1 1,075 i have a couple questions to ask 1: When a satellite is in eclipsical orbit, the total energy should stay the same... Feb4-05 09:19 AM Doc Al 2 845 Why do mountain roads rarely go straight up the slope but wind up gradually? Feb4-05 07:02 AM Mk 11 3,446 Is free electron denisty how many electrons per volume unit, flowing through? Do the electrons actually flow through?... Feb4-05 06:39 AM Mk 0 7,358 I got this wrong on a midterm, i have NO IDea absolutely how to solve this type of problem. I asked my TA too and he... Feb4-05 03:36 AM krab 1 761 http://www.newscientist.com/channel/space/mg18524846.500 Feb4-05 02:16 AM Ivan Seeking 9 1,032 having trouble showing that X(t) = Xo cos (wt) + (Vo/w) sin(wt) been fiddling with equations for a while and cant see... Feb3-05 06:28 PM gerben 2 665 Hi everyone, I’m a wannabe scribbler of Science Fiction trying to get things right in a story I’m working on...so... Feb3-05 04:05 PM Tide 1 712 Hi. I understand the equation, but I don't understand logically in my head why it is that way. Maxwell's equations,... Feb3-05 10:47 AM Vern 5 1,048 ohk, i was working on some code work during a pre-calc boring reveiw fest and i want to stte some things that i seem... Feb2-05 04:58 PM Arsonade 7 1,108 hi everybody, I want to know about the mathmatics of deriving this laws. or in another word I want to know how... Feb2-05 03:43 PM da_willem 3 5,185 Do u think it is possible to convert matter to energy and back into matter the same way without harm? Feb2-05 08:21 AM pmb_phy 2 690 I thought this would have to go in the homework topic, but its not really homework its more off a project - so I... Feb1-05 03:29 PM richnfg 0 2,793 I've got a question ... if atoms cannot be compacted, beyond a certain minute level, how can they exist inside a black... Feb1-05 02:31 PM Undomiel 0 1,161 Hello, Curious to know, does an engine at idle have potential energy? For instance would an airplane sitting at the... Feb1-05 02:12 PM Tom Mattson 3 690 Outside, I have a south-facing 3'x8' banner that is hung on a fixed sign connected to an L-shaped building. The wall... Feb1-05 02:05 PM bognemark 2 1,053 1. Maxwell's equations do not hold in NON INTERTIAL reference frames, right?? 2. Lets say you have a charge which... Feb1-05 10:26 AM pmb_phy 7 1,270 Are pyroelectricity and the peltier-seebeck effect the same thing? Feb1-05 10:18 AM Gonzolo 2 4,492 Hi. I have a data gaussian g(t) and data that I suspect is a convolution (g*f). I want to find f(t), so I need to... Feb1-05 10:13 AM Gonzolo 10 6,028 I want to know the speed of sound at sea level. :confused: I also want to know the exact speed of light in... Feb1-05 08:35 AM russ_watters 3 1,383 Hi everyone, I'm new to this forum. I'm not a physicist or a mathematician, but do try to make sense of the way... Feb1-05 08:24 AM ZapperZ 3 1,779 I need help on these ?'s. They are very confusing to me. Can someone please help me. -Here they are: >Two... Jan31-05 11:56 PM Sirus 1 2,922 how come different sounds are made when you hit different objects together, when in reality, the two objects aren't... Jan31-05 09:42 PM Lewis Zack 4 1,221 Mass-energy equivalence is fundamental in relativity, but it seems like energy and momentum are also different aspects... Jan31-05 07:38 PM pervect 1 2,027 For recreational/educational purposes, i am looking into building a small cannon which would shoot projectiles of... Jan31-05 05:58 PM dekoi 5 1,141 I wanted an equation to find the energy being used for time travel instead of space travel. Tell me if this works. ... Jan31-05 04:07 PM demosthenes_001 4 964 Hi, I have a question wich should fit in here: - How big in size may an object be before it's noticed on a radar... Jan31-05 04:02 PM chroot 4 713 Many persons think that classical systems with varying mass obey the fundamental law: \vec{F}=\frac{d\vec{P}}{dt}... Jan31-05 03:10 PM arildno 16 1,603 This question bothered me for some time. From what i have seen in textbooks, dispersion occurs as soon as white... Jan31-05 02:05 PM Gonzolo 5 5,129 If a charge is accelerating, but you are also accelerating WITH the charge, will you see any radiation? I.e. will the... Jan31-05 01:57 PM pmb_phy 15 1,245 Hello, New to this message board (and very happy to have found it). I am reading a book on cosmology by Steven... Jan31-05 01:02 PM p.falk 4 1,090 Hi, Are the speeds of all different colors of light exactly the same? And has this been done experimentally? Have... Jan31-05 12:10 PM Gonzolo 8 1,556 Is there a cheap way for me to get light from sound? If not, is there an expensive way? Jan31-05 11:50 AM Gonzolo 3 1,441 What caused my picture to turn out the way it does. I really like it. If you would like I could upload a full res... Jan31-05 09:59 AM DaveC426913 12 1,201 Hey, I am currently trying to calculate how much current a "wire" of very small dimensions can take. This "wire" is... Jan31-05 04:15 AM danesh 2 1,273 Show that the equation is homogeneous with respect to units: I = nAQv I cant prove it, please help Jan30-05 03:22 PM arildno 4 2,549