Sign Definition and 595 Threads

A sign is an object, quality, event, or entity whose presence or occurrence indicates the probable presence or occurrence of something else. A natural sign bears a causal relation to its object—for instance, thunder is a sign of storm, or medical symptoms a sign of disease. A conventional sign signifies by agreement, as a full stop signifies the end of a sentence; similarly the words and expressions of a language, as well as bodily gestures, can be regarded as signs, expressing particular meanings. The physical objects most commonly referred to as signs (notices, road signs, etc., collectively known as signage) generally inform or instruct using written text, symbols, pictures or a combination of these.
The philosophical study of signs and symbols is called semiotics; this includes the study of semiosis, which is the way in which signs (in the semiotic sense) operate.

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  1. Amith2006

    Confused on mirror/lens sign conventions

    Sir, I am confused on what sign conventions to follow. I reffered 5 or six books which says that focal length of convex mirror is positive and focal length of concave mirror is negative. But in Resinick & halliday,wikipedia and many other websites it is given the opposite. Please help me!
  2. E

    Is the Work Done on a System Positive When There is Compression?

    In terms of the thermodynamic identity: dU = {\tau}d{\sigma} - pdV the term for the work done on the system (-pdV) must be positive if there is a compression, in which case dV would be negative, correct? If one wanted to write the identity in terms of the work done *by* the system, you...
  3. Ivan Seeking

    UFO study finds no sign of aliens

    http://news.bbc.co.uk/2/hi/uk_news/4981720.stm It has long been suspected that this sort of thing may account for some UFO reports - perhaps a good number of the more interesting cases. Of course it remains to be shown that such a phenomenon really does exist that can affect humans to the...
  4. Schrodinger's Dog

    News What would it take the US to sign a protocol?

    I believe it was world something or other day in the US yesterday so with that in mind:- What would it take for the US to sign an agreed protocol to help combat climate change? I read recently that the US has a population of 298 million roughly yet produces more CO2 than Europe population 450...
  5. D

    SHM damping coefficient which envelope sign?

    Hi, I'll get right away to the point. I'm determining damping coefficients from motion sensor traces of a damped oscillator. I have gone through the standard procedure of taking natural logs of the sine wave peaks and drawing graphs etc, however what puzzles me is that the SIGN of the damping...
  6. Y

    Neon Sign Light: Continuous Spectrum or Few Colors?

    need to hand in an assingment in an hour. would appreciate help on this : "Does the light emitted by a neon sign constitute a continuous spectrum or only a few colors? Defend your answer" thank you
  7. G01

    Solve Integral Error: \int\frac{1+e^x}{1-e^x}dx

    \int \frac{1+e^x}{1-e^x}dx = \int \frac{dx}{1-e^x} + \int \frac{e^x}{1-e^x}dx The second integral can be done by the substitution u = 1-e^x du = -e^x dx So the second integral becomes: \int \frac{du}{u} = \ln|u|+C In the first integral, you can use the substituion: w = e^x...
  8. T

    Sign Magnitude: 10011101 & 11001100 Decimal Value

    for 10011101 and 11001100 ,what is the decimal value in sign magnitude format (8bits) ?? pls help
  9. M

    Does this negative sign even matter in sin(x)?

    Hello everyone, when I'm doing these problems i always make sure i put a negative inside the sin(x) function, then just later take it out like cos(2t)+sin(-2t) = cos(2t)-sin(2t); Because sin is an odd function. But my professor says f it and never does, for instance here is my work, i came out...
  10. Evo

    Business Budget Cuts: Sign of The Times?

    Businesses just keep tightening their budgets more and more. Last year the division I work for flew everyone to Las Vegas to celebrate the annual branch kickoff. This year, we're driving down the block to a cheesy strip mall type convention center for TWO hours to celebrate. I'll bet if I'm...
  11. Mk

    News China Urges US to sign the Kyoto Treaty

    http://news.yahoo.com/s/ap/20051201/ap_on_re_ca/canada_climate_change Those countries are missing out on the moolah. :smile:
  12. G

    Finding Derivative, but wrong sign

    Ok, I am doing my calculus homework, but sometimes I get a negative in the wrong place... Here is an example: The solution I got for the derivative attached is on the numerator: 5e^x(9e^x)-5e^x(4+9e^x) In the solution, the negative sign is on the other side?? I don't get it
  13. B

    How do you do a sign function?

    I have always used a calculator to find the sin when the angle is given. But how would you figure this out if you didn't have a calculator
  14. S

    Understanding Absolute Value Sign in Derivative

    Hi So I am a little confused about the absolute value sign here. Is the derivative right: [x-1/|x-1|]e^x + |x-1|e^x But what do I do when I set this to zero? Do I get two expressions, one for x>1 and one for x<1 ? (thus removing the absolute value signs)
  15. N

    Free way Sign Problem - Statics

    Q. The base of the freeway sign is attached to its foundation with four bolts.The four bolts must be able to resist the twisiting of the pole that is caused by the wind. Assume each bolt carries the same force. If the diameter of the bolt circle is 0.9m, calculate the horizontal (shear) force on...
  16. M

    Lenses/Mirrors, [1/f = (1/do+1/di)] sign help

    Hello Im really confused on the signs for f, do and di in this equation.. Please tell me if I am correct.. but here is how i presently understand if For definition sake, the 'front' of a mirror is where you would normally stand to look in a mirror, and the 'front' of a lens (like a camera)...
  17. M

    Fermi-Walker transport - problem with a minus sign

    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...
  18. A

    EASY Q (Multiplying sign rules)

    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...
  19. S

    Troubleshooting Hotmail Sign Up: Get Help Checking Your Mail

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

    Integration by Parts: What's the Sign of that Last Term?

    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...
  21. tony873004

    The Mystery of the Minus Sign: Finding the Cross Product of a x b

    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?
  22. L

    Statics/rotational dynamics:hanging sign

    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...
  23. G

    Hanging Sign Problem and Pulley Problem

    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...
  24. maverick280857

    Sign Convention for Geometrical Optics

    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...
  25. H

    What are the sign conventions for force in physical chemistry?

    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...
  26. R

    Can we do this with greater than sign

    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:
  27. X

    Do You Know the Words to "The Lumberjack" Song?

    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...
  28. M

    News China, you're just a developing country, so you don't have to sign kyoto

    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...
  29. Tsu

    News Sign Up Now for the PF Cyber Bus Trip to Tom's

    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...
  30. 0TheSwerve0

    What's Your Sun Sign? Share Your Zodiac Placement!

    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)
  31. S

    Find out the Minimum Diameter Wire for a 176.00N Sign

    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...
  32. wasteofo2

    News Supporters of the war: what will it take for you to sign up for the military?

    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...
  33. S

    Solving Hanging Sign Problem: Find Tension, Horizontal & Vertical Force

    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...
  34. A

    Best sign of extraterrestrial intelligence?

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

    News 368 Economists sign letter opposing Kerry (6 Nobel laureates)

    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.
  36. quasar987

    Volume of a parallelepiped's sign

    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...
  37. C

    Using differentiation under integral sign to proof equality of mixed partials

    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...
  38. C

    Solve Cap'n Threelegs' Puzzling Sign Problem!

    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...
  39. O

    Calculating Focal Length Using Sign Conventions for Lenses

    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...
  40. J

    Euler's Equation: A sign from god?

    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...
  41. frankR

    Equal sign with a triagle above it?

    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
  42. H

    Differentiation under the integral sign

    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...
  43. H

    Writing degree sign on the microsoft word?

    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!
  44. A

    Is atheism a sign of intellectual weakness?

    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...
  45. C

    What function does the sign wave represent in sound and light?

    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...
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