Sign Definition and 579 Threads

I am looking at the Fermi-Walker transport of a tetrad transported by an observer in circular motion in Minkowski space. The 0-component of the tetrad should be the 4-velocity of the observer, which should therefore satisfy the FWT DE, but I'm finding that it is equal to the negative of what it...

Hi, I've tottally confused myself over the mutiplying rules. Can someone please tell me all the rules +x+ = -X+ = +X- = -X- = Because I am stupid and keep messing up my polynomials with them. look forward to posting many easy questions for you guys, Dam some of this stuff is...

Anyone who has problem in signing up in Hotmail account? I can't check my mails!

I forgot a little detail in the integration by parts formula Is it \int u \,dv = uv + or - \int v \,du I don't remember if its plus or minus...

find the cross product a x b of the vectors a = 5.0m,i and b=4.3m,k 5.0m\ast 4.3m\ast \sin (90)=22m^2,\hat {j} The back of the book gives -(22m^2)\hat {j} Where does the minus sign come from?

A sign has a mass of 1050 kg, a height h = 1 m, and a width W = 4 m. It is held by a light rod of length 5 m that is perpendicular to a rough wall. A guy wire at 23° to the horizontal holds the sign to the wall. Note that the distance from the left edge of the sign to the wall is 1 m. Suppose...

Okay, we've been studying this for a while but I still always seem to forget how to do these and they aren't anywhere in my Physics book. Problem 1: Sign hanging at rest from two cables. One is angled at zero degrees while the other is at 135 degrees. The sign is 10kg. Find the tension...

Hi Could someone point me to websites with tutorials on the real-virtual sign convention for geometric optics (and possibly other known conventions too)? I've been googling for some time but the results aren't too satisfying. PS--Tutorials with mathematics are preferred... Thanks and...

hey there! i am taking a physical chemistry course at my college. an assignment given was about miniature machines: "pulling" nanowires. one of the questions asked is concerning the types of sign conventions of force. i have tried to research this topic had have trouble finding out the...

Can we do this with "greater than" sign If (2x-9)(x+3)\geq0 then can we say (2x-9)\geq0 and (x+3)\geq0 and solve them seperately ? I am not sure if i can do this because of the \geq sign. Hmm wrong section. Actually this is part of my homework anyway. :biggrin:

does anyone know the words to Lumberjack? i figured people out here know a lot and maybe someone kwons the words to the Lumberjack song... i think it sort of goes like I'm a lumberjack and I'm okay Eat all night and I sleep all day I'm a lumberjack and it's okay I work all night...

But you make the second most pollution on earth... http://www.channelnewsasia.com/stories/afp_asiapacific/view/120966/1/.html But of course, we Americans are just big fat greedy devils! Or could it have to do with the fact that the 'holy grail' of climate control pragmatically targets the...

Here are some pictures of "our" bus: :biggrin: You like? http://hosted.yourimg.com/04/339/22/PFBus.jpg http://hosted.yourimg.com/04/339/22/PFBus1.jpg http://hosted.yourimg.com/04/339/22/PFBus2.jpg http://hosted.yourimg.com/04/339/22/PFBus3.jpg...

I was going to make a poll including each sign, but there are only 10 options. Just post your sign (and Moon's sign or Ascendant if you know it). The only thing I'd anticipate is an absence of Taurus and Capricorn. Unsure, born on the cusp? Be sure Sagittarius (Aquarius Moon)

This one is confusing me: -----The yield strength of a material is the largest stress a material can support without permanently elongating (like a slinky stretched too far). A brass wire 2.10m long is to support a 176.00N "Eat At Joe's" sign without permanently elongating. The wire...

It always amazes me how people who are young enough and fit enough to serve in the military can both support the war, and yet not sign up for the military. The way I see it, if you think there's a cause out there worth fighting and dying for, then you should be willing to fight and die for it...

A shop sign weighing 206 N is supported by a uniform 132 N beam of length L = 1.89 m as shown in figure below. The guy wire is connected D = 1.19 m from the backboard. Find the tension in the guy wire. Assume theta = 43.0 o Find the horizontal force exerted by the hinge on the beam. Find...

http://www.planetary.org/news/2004/dyson_spheres.html

Take this for what you think it's worth. http://www.nationalreview.com/nrof_comment/release_bc04_economists.html The 368 signatories are shown at the linked site.

I have this problem that reads a) Prove that the three-product (A.(B x C)) of the vectors A, B and C where A, B and C are not lying in a single plane, is the volume of the parallelepiped whose edges are A, B and C with positive or negative sign according to wheter a right-hand screw rotated...

Hello. Excuse my english, it is not my natal tongue. I have a question about real functions of two real variables. Does someone knows how to use differentiation under the integral sign to proof the equality of mixed partials ? I have read said proof in a book of an english author, David...

I recently found this problem online and wasn't able to figure it out. Maybe someone here can figure out the puzzle and explain how they got it! In celebration of Yurbles coming in for training, Cap'n Threelegs decided to make a sign for his Swashbuckling Academy that read "Welcome Yurbles...

Okay for the most part I understand the concepts involved but I'm having some trouble with this question. The distance between an object and its upright image is 20.0 cm. If the magnification is 0.500, what is the focal length of the lens that is being used to form the image? Now...

The first time I saw Euler's equation, it blew my mind. e^{i\pi}+1 \equal 0 Here, we have three of the most important numbers in math, all related to each other in such a remarkably compact equation. Does anyone know what this means? I think you can prove this through Taylor Series...

In my EM textbook it uses a equal sign with a triangle on top to define the intrinsic impedence of a lossless medium. I think it means definition but I'm not certain. The text is 2004 edition of author Ulaby titled Fundametals of Applied Electromagnetics, pg. 265. Thanks

Hello everyone, This is my first post. I would like to understand better the idea of differentiation under the integral sign. I read about it in http://mathworld.wolfram.com/LeibnizIntegralRule.html and Feynman's autobiography, about evaluating an integral by differentiation under the...

please help! i need to type up some problems that involve with temperature. i was wondering how do you the degree sign on the microsoft word? you know, the little circle? thanks!

I recently read an argument that atheists are fools, not for disbelieving in God, but for believing too much in themselves. The writer argues that what makes theists superior to atheists is not their faith, but in fact their doubt. I can't speak for every theist, but it's certainly my case that...

I know that in electronics the sine-wave applies to AC voltage because it is constantly going from negative to positive, and back to negative again causing an analog wave of the rising and collapsing voltage and sometimes magnetic fields. But sound and light are supposed to create waves by just...