What is Sign: Definition and 592 Discussions

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. K

    What does the 'not equal to' sign mean?

    the 'not equal to' sign ( =/= )? If I say, blue =/= red. could you simply say: blue = 0 red? Or: life =/= death... mean life = 0 death? Does the not equal to sign mean merely 'incompatible' or does it mean 0 of the thing =/=? How do you use that sign?! I may be far off
  2. B

    Sign in Conservation of Angular Momentum Problem

    Homework Statement A girl of mass M stands on the rim of a frictionless merry-go-round of radius R and rotational inertia I that is not moving. She throws a rock of mass m horizontally in a direction that is tangent to the outer edge of the merry-go-round. The speed of the rock, relative to...
  3. R

    Sign Convention - Physics - Optics

    [SOLVED] Sign Convention - Physics - Optics I was just looking at some sign conventions and I was wondering if this is true: Along the principle axis, if Si > 0, then does that mean you have a real, inverted image? Also along the principle axis, if So < 0, then does that mean you have a...
  4. P

    How to Calculate Tension in a Hanging Sign Supported by Two Ropes

    [SOLVED] Tension- Hanging Sign A 20.0 kg sign is being held up by 2 ropes. Each rope makes a 60 degree angle with the sign. So there is an upright triangle, each angle 60 degrees. I have to calculate the tenstion in the two ropes. So far, I have \Sigma F_{}y=ma_{}y +Fa_{}1sin60 +...
  5. R

    Voltage - Sign convention problems

    Hey guys, I need some help clearing up voltage signs, its always confusing me and I have my final this Friday. First off I'm not talking about voltage in a circuit, but rather if there is an electric field caused by a charge distribution. First off, I understand potential energy for gravity...
  6. D

    Minus sign before the 2nd integral

    [Solved] Where did I go wrong? \int \frac{(x-2)}{x(1+x^2)}dx \int \frac{x}{x+x^3}dx - \int \frac{2}{x+x^3}dx I choose u = arctan(x) so du = \frac{1}{1+x^2} and \int \frac{x}{x+x^3} = \int \frac{1}{1+x^2} 1) \int \frac{1}{1+x^2}dx = arctan(x) 2) \int...
  7. C

    Find Height of Sign for Optimal View at 60 Feet

    At the top of their 50 foot tall sales building, there is a 10 feet tall sign. But he wants to replace it with a sign for which the ideal viewing distance is 60 feet from the building. For an observer, the angle between the lines of sight from the observer's eye to the top and the bottom of the...
  8. DaveC426913

    Spam bounce back sign of zombiism?

    Occasionally I get administrator emails that indicate emails bounced back. The email is some spam thing. It looks for all the world like I sent that piece of spam, though I have the latest spam blocking s/w. Does this, in fact, mean that my system is affected, or is it a fake?
  9. S

    Hanging sign, torque and pivot points

    Homework Statement There is a sign of mass M that is attached to a rigid bar perpendicular to the ground. There is also a rope attached to the sign at the same point, then pulled out at an angle 45 degrees below the horizontal up to the ceiling. a) Consider the rigid bar to be at...
  10. N

    Optics: Applying Sign Conventions Twice?

    Please provide me with some help in optics. This doubt is in relation to the use of sign conventions in optics. Whenever we prove anything in optics, say for example, when we prove the mirror formula or the lens formula or the lens-maker's formula, we apply the sign conventions in the derivation...
  11. F

    Curio: general sign for all elements.

    As we have seen some mathematical sign lately in this group, because I put you in the drawing of the general sign of any element. You also can see more searching “from zero to infinite, ferman”. Thank you.
  12. P

    Electric Potential (Why the opposite sign?)

    Homework Statement Two large, parallel, conducting plates are 12 cm apart and have charges of equal magnitude and opposite sign on their facing surfaces. An electrostatic force of 3.9 \times {10}^{-15} N acts on an electron placed anywhere between the two plates. (Neglect fringing.) (a)...
  13. K

    Hanging Sign Problem: Find Angle & Distance from Ceiling

    Homework Statement If you are hanging a sign from the ceiling with two wires, each with a safe working load of 20N. The hooks at the top of the sign are 2.0 meters apart while the hooks in the ceiling are 4.0 meters apart. A) If the sign weighs 30N what is the minimum angle to the horizontal...
  14. M

    Understanding the Op Amp Minus Sign Symbol

    What does it mean when an op amp has only a minus sign in its symbol? Is the positive terminal at ground, or is it at some arbitrary voltage?
  15. A

    Delta Sign Confusion: Solving Depth of Grand Canyon

    Homework Statement Hans stands at the of the Grand Canyon and yodels down to the bottom. He hears his yodel echo back from the canyon floor 5.20s later. Assume that the speed of sound in air is 340.0m/s. How deep is the canyon at this location? I made a chart. Velocity Original = 340...
  16. P

    Gauss' Law (Why the opposite sign?)

    Homework Statement 4. In Fig. 23-28, a butterfly net is in a uniform electric field of magnitude {E = 3.0} mN/C. The rim, a circle of radius a = 11 cm, is aligned perpendicular to the field. The net contains no net charge. Find the electric flux through the netting...
  17. C

    Calculate Tension in String 1 for Hanging Sign Problem

    I'm working on this hanging sign problem: A sign hangs precariously from your prof's office door. Calculate the magnitude of the tension in string 1, if θ1 = 27.42°, θ2 = 67.35°, and the mass of the sign is 9.9 kg. I was wondering if I could put 9.9*9.8 as a leg in the middle of the...
  18. H

    How to determine when a function changes sign?

    Hi all. Say, I have an alegebric function, e.g. f(y;a)=y^4+b*y^3+c*y^2+d*y+e, where the coefficients b,c,d and e are all depends on a single parameter, a. What I want to do is to check what is the condition of a for the function f(y;a) to change its sign between 0 and 1+a, do you have any...
  19. B

    How close can you get to a stop sign before you start braking?

    Please help! This is urgent! Homework Statement 1) A typical car's brakes can create a maximum acceleration of less than 5 m/s^2 . How close can you get to a stop sign before you start braking? Homework Equations no idea at all since there isn't even enough information given to solve...
  20. H

    What is an equal sign with a strait line down the middle of it mean?

    What does an equal sign with a straight line down the middle of it mean?
  21. Alpha Russ Omega

    Does this device follow Passive Sign Convention?

    Hello: I need help determining if I and V assignments follow the passive sign convention. Here is the image of the circuit: http://img178.imageshack.us/img178/9572/pic1xu2.gif I know that in order for it to follow PSC the current I needs to flow towards +V. I'm not sure if that is...
  22. A

    LaTeX Latex - how to get non-italic UK pound sign

    Latex - how to get non-italic UK "pound" sign I'm using MikTex. When I do \usepackage{times} and then use \pound or \textsterling in non-maths mode, I get the italic version of the "pound" symbol from the Times Roman font. I want a non-italic pound symbol. I also get this message in...
  23. G

    Gravitational Force(Why the negative sign?)

    Homework Statement How come it is said that attractive forces such as gravitational force have negative sign? And how come the sign is ignored in the case of gravitational force? And also, how come gravitational potential energy carries a negative sign? Is it because the displacement of the...
  24. T

    Difference in Sign for 6.4 Equation

    I have a hard time trying to derive the equation in 6.4 . This is what I've done, and as you will see I have a sign difference compared to his. http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=PRVDAQ000070000001015012000001&idtype=cvips&prog=normal Starting with page 8...
  25. Loren Booda

    Synthetic, exotic particles as a sign of extraterrestrial life

    Would obviously synthetic particles traveling through space be a choice to broadcast the presence of life? Likewise, say we detected an unnaturally large cross section of an otherwise rare particle impinging upon Earth; might that vestige be a purposeful indication of extraterrestrial civilization?
  26. I

    Why do people sign their name?

    at the bottom of a post? i mean your userid is just to the left of the post? is it so that if someone murders you and tries to infiltrate our ranks we'll know? maybe it's because some of you write such long posts that by the time one reads the whole thing scrolling up is counterproductive? bob
  27. B

    Uncovering the Metric Sign in Einstein's Equations

    hi. 1. Why does the sign of the metric have to be (+,-,-,-) or (-,+,+,+)? meaning why does the sign in front of the time part of the metric have to be different than the signs in front of the spatial part of the metric? is there a good answer for this question other than it gives the right...
  28. A

    Sign confusion of Mirrors/Lenses.

    To clear up the confusion of signs to use for mirrors and lenses. Would this be a correct way of memorizing the signs? For the equation: 1/s_o+1/s_i=1/f Mirrors: Concave: Since light actually converges at the focal point, it's positive. Any image that is on the same side as the focal point...
  29. hagopbul

    Complete Physics Studies: Sign Up for 4th Year Specialization

    i am studing physics and i Sign up for this courses and I think it is to much: 1st year: Introduction to physics I Introduction to physics II Mathematic (matrixes) Mathematic (Calculus & Analysis) Mathematic (matrixes & Vectors) Mathematic (probability theory) Introduction to chemistry...
  30. F

    Sign and direction on charges, coulumbs law

    the material is over coulombs law, and i am having a rough time understanding the business of the sign's of the charges and the direction of the charge at the same time. here is a problem from the text.: Two charges are located on the x-axis with q1 = 2.3 x 10^-8 C at the orgin, and with q2...
  31. J

    Sign magnitude/1's Complement/2's Complement

    Homework Statement a.) What is the lowest number represented by a 12-bit machine using Sign Magnitude? b.) What is the largest? c.) What decimal number does the bit pattern "101001010010" represent?Homework Equations For a and b: Signed integer ranges for N bits (I don't know if this is...
  32. Amith2006

    Sign of g-factor Value: Is It Positive or Negative?

    Homework Statement 1)I have a doubt regarding the sign of g factor value. In Wikipedia the g-factors are given as: Orbital g-factor Mu(L) = g(L)[Mu(B)L]/h_bar Where g(L)=-1 is the orbital g factor Spin g-factor Mu(S) = g(S)[Mu(B)S]/h_bar Where g(S)=-2 is the spin g factor Lande...
  33. A

    What Does Changing Sign in Derivatives Mean for Completely Monotone Functions?

    Homework Statement This is ralated to completely monotone functions. if a function and its successive derivative changes sign then what does this mean? Homework Equations The Attempt at a Solution
  34. M

    Minus sign in forces in space problem.

    minus sign in "forces in space" problem. Homework Statement see picture for problem. Homework Equations please see a picture (one is of problem, the other contains the relevant formula). The Attempt at a Solution I was able to solve the whole thing, then looked at the solution...
  35. A

    Why is there a negative sign in the formula for inductive voltage?

    Hi, Let L be an inductance, then you find the following formula in textbooks (high school level): U_ind = - L dI/dt When you actually do calculations for circuits, you see that the minus sign is wrong. So why do they put it there?
  36. T

    Sign Conventions: A Cultural Study

    I guess this is more of an anthropological post. Is there any pattern to which sign convention people prefer? Or is it just a matter of which you were exposed to first?
  37. P

    Electrode Sign: + or -? Understanding Cell Potential

    Electrodes in cells usually have a sign of either + or - My textbook talks about the + as because the electrode is positively charged and - when negatively charged. But is that correct? The electrodes are meant to be conductors and shouldn't be charged at any time. When they do, the ions...
  38. J

    Sign of the gyromagnetic ratio

    Hi, I have posted this doubt in other forums and people don't know the answer. (sorry if my English is not very good!) Let's see: to obtain the operator for the magnetic moment component of a particle, we have to apply a few factors to the spin operator, and one of them, the so-called...
  39. F

    Passive sign convention (negative watts, and negative current confusion)

    This is my (error full?) understanding from my readings: 1. positive current flowing into a positive terminal of let's say a rechargeable battery is power being absorbed by the battery...so positive watts 2. negative current flowing into a positive terminal encounters the higher electrical...
  40. A

    Quick question on sign convention for Work in Columbs

    Homework Statement http://online.physics.uiuc.edu/cgi/courses/shell/phys102/fall06/prep2a.pl?practice/exam1/fa06 Homework Equations W =F*D The Attempt at a Solution I have it solved, now i thought - would be if i put work into the thing to move it but looking at it since both of...
  41. D

    Neglecting Torque Sign for Acceleration Calculation

    If you have two blocks connected over a pulley, and are using the torque on the pulley to calculate the acceleration, then you should disregard the sign of the torque, always treating it as positive, no matter which direction it rotates? Is this right? Thanks, Dorothy
  42. tony873004

    Symbols are used instead of an equal sign

    Sometimes the following symbols are used instead of an equal sign. I think the single one ~ means "is proportional to". One of the other ones means "is approximately". Which one is it? I'm guessing the second one because LaTex calls it approx. When are the others used? \begin{array}{l}...
  43. M

    Understanding Vectors: Homework Help and Tips for Solving Vector Problems

    I have been having a really rough time on my 3 homework problems tonight...I don't really understand vectors, so any help would be appreciated! Sorry about the no LaTeX, I don't know how to do the vector sign:confused: Anyway... 1.Given the Vectors U=2i(hat)-3j(hat)= <2,-3> and...
  44. P

    Kirchoff's 2nd Law : Sign taking method

    I know Kirchoff's 2nd law but when applying to an electrical circuit i am bit confused :confused: with taking correct signs for emf,product of resistor & currect etc. Anyone please help me to solve problems related with Kirchoff's 2nd law in an easy way.
  45. A

    Understanding Standing Wave Sign Conventions

    Hi. Okay, this has been driving me crazy. When combining two given waves into a standing wave equation, how do you know which sign to put in front of the amplitude? All the examples I've been finding seem to contradict each other. Here are three examples from my textbook: 1. Incoming Wave...
  46. L

    Sigma sign in chemistry vs math

    Hi there, We are about to use that sigma sign in chemistry we have however not got told about it in math. SO therefore I am asking you if you could give me a brief introduction to it and how to use it and etc.
  47. S

    Differentiating under the integral sign

    Can someone point me to a reliable source (textbook, website) that teaches this technique? It seems like no course at my university covers this technique even though it is quite useful for solving particular integrals!
  48. 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!
  49. 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...
  50. 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...
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