Negative Definition and 1000 Threads

In mathematics, a negative number represents an opposite. In the real number system, a negative number is a number that is less than zero. Negative numbers are often used to represent the magnitude of a loss or deficiency. A debt that is owed may be thought of as a negative asset, a decrease in some quantity may be thought of as a negative increase. If a quantity, such as the charge on an electron, may have either of two opposite senses, then one may choose to distinguish between those senses—perhaps arbitrarily—as positive and negative. Negative numbers are used to describe values on a scale that goes below zero, such as the Celsius and Fahrenheit scales for temperature. The laws of arithmetic for negative numbers ensure that the common-sense idea of an opposite is reflected in arithmetic. For example, −(−3) = 3 because the opposite of an opposite is the original value.
Negative numbers are usually written with a minus sign in front. For example, −3 represents a negative quantity with a magnitude of three, and is pronounced "minus three" or "negative three". To help tell the difference between a subtraction operation and a negative number, occasionally the negative sign is placed slightly higher than the minus sign (as a superscript). Conversely, a number that is greater than zero is called positive; zero is usually (but not always) thought of as neither positive nor negative. The positivity of a number may be emphasized by placing a plus sign before it, e.g. +3. In general, the negativity or positivity of a number is referred to as its sign.
Every real number other than zero is either positive or negative. The non-negative whole numbers are referred to as natural numbers (i.e., 0, 1, 2, 3...), while the positive and negative whole numbers (together with zero) are referred to as integers. (Some definitions of the natural numbers exclude zero.)
In bookkeeping, amounts owed are often represented by red numbers, or a number in parentheses, as an alternative notation to represent negative numbers.
Negative numbers appeared for the first time in history in the Nine Chapters on the Mathematical Art, which in its present form dates from the period of the Chinese Han Dynasty (202 BC – AD 220), but may well contain much older material. Liu Hui (c. 3rd century) established rules for adding and subtracting negative numbers. By the 7th century, Indian mathematicians such as Brahmagupta were describing the use of negative numbers. Islamic mathematicians further developed the rules of subtracting and multiplying negative numbers and solved problems with negative coefficients. Prior to the concept of negative numbers, mathematicians such as Diophantus considered negative solutions to problems "false" and equations requiring negative solutions were described as absurd. Western mathematicians like Leibniz (1646–1716) held that negative numbers were invalid, but still used them in calculations.

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  1. PeteyCoco

    Programming Function With Cut On Negative Imaginary Axis

    The Function To Be Programmed \sigma_m=\frac{4(n_r^2 -1)J_m(n_r k R)}{\pi^2kD_m^+(kR)D_m^-(kR)} where D_m(z)=n_rJ'_m(n_rz)H_m(z)-J_m(n_rz)H'_m(z). The '+'/'-' superscripts indicate the limits as z approaches the branch cut, which lies along the negative imaginary half axis, from the positive...
  2. D

    Probability Problem (maybe on Negative Binomial Distribution)

    The following problem is from "Probability and Statistics in Engineering - Hines, Montgomery" A potential customer enters an automobile dealership every hour. The probability of a salesperson concluding a transaction is 0.10. She is determined to keep working until she has sold three cars...
  3. T

    Precise Definition of a Limit at Negative Infinity

    I'm working through some problems from Stewart's Calulus, 6ed. and am having some difficulty with certain limit proofs. In particular, there is no definition provided for limits of the form: $$ \lim_{x \to - \infty} f(x) = L $$ One of the exercises is to come up with a formal definition...
  4. A

    Simpson's Rule with negative values

    Hey guys, Not claiming to be an expert on numerical methods here but I am doing some digital integration using simpson's rule that takes 10 samples a second to provide me with the "approximate" integral for that time period. Right now I am currently taking the magnitude of the value I...
  5. Mogarrr

    Parameter space for the negative binomial distribution

    Homework Statement For the negative binomial distribution, with r known, describe the natural parameter space Homework Equations the pmf for the negative binomial distribution with parameters r and p can be 1) P(X=x|r,p)= \binom {x-1}{r-1}p^{r}(1-p)^{x-r} where x=r,r+1,... , or 2)...
  6. N

    Regarding electric potential with respect to a negative charge

    Homework Statement If I have a electric source charge, does that mean that electric potential increases as r increases (because it gets increasingly less negative as you go farther from the source charge) as opposed to a positive charge in which potential energy would increase as r...
  7. N

    Why do negative charges spontaneously accelerate when they move to?

    Homework Statement Why do negative charges spontaneously accelerate? The book I am studying from asked me to verify this statement: Negative charges spontaneously accelerate and increase in kinetic energy when they move toward a point of higher potential. I don't understand why...
  8. Dethrone

    MHB Solids of Revolution - Negative Volume

    I encountered a problem where the answer I got was negative. Calculate the volume bounded by $y=x^2-5x+6$, $y=0$, about y-axis. An easy question that is best done with the cylindrical shell method: $$V=2\pi \int_{2}^{3} x(x^2-5x+6)\,dx$$ $$V=\frac{-5\pi}{6}$$ I think I know why it's...
  9. N

    Photodiode and negative resistance

    Our professor has asked us why would a photo diode when shined with light, produce no negative resistance. So far, the only thing I can come up with is because it is in photo conductive orientation (as opposed to photo voltaic) increasing Dark Current thereby eliminating the negative...
  10. O

    Radical with negative radicand squared

    Can someone explain this for me. sqrt x^2 = x (sqrt x)^2 = x Yet sqrt -1^2 = |x| = -(-1) = 1 (sqrt -1)^2 = (sqrt -1)(sqrt -1) = -1
  11. G

    Negative Energy in Quantum Mechanics: Can Particles Exist?

    I'm coming here from going through the Dirac delta potential in QM to clear my mind about the case when E < 0, which as a result produces the single bound state solution in that potential. The thing that's vexing my soul(if we have one anyways) is the fact that a particle is taken to be in...
  12. R

    Infinite Acceleration, Conservation of Energy, and Negative Mass

    I've read that the Alcubierre Drive depends on the existence of negative mass, but I've seen that physicists say it could violate the conservation of energy. Their reasoning is that basically a negative mass and positive mass would interact in a perpetual motion sort of way that eternally...
  13. Mogarrr

    Negative binomial transformation and mgf

    Imo, this problem is crazy hard. Homework Statement Let X have the negative binomial distribution with pmf: f_X(x) = \binom{r+x-1}{x}p^{r}(1-p)^{x}, x=0.1.2..., where 0<p<1 and r is a positive integer. (a) Calculate the mgf (moment generating function) of X. (b) Define a new...
  14. D

    Positive, negative, complex determinants

    Hi, I have a rather trivial question but google did not really help me. So far I was always familiar with the fact that the determinant of a square matrix is positive. But it is not. When I randomly execute det(randn(12)) in MATLAB I get a negative determinant every couple of trials...
  15. M

    Negative in a Electric Potential Energy/Kinetic Energy Question

    Homework Statement My questions reads: An electron is pulled away from a fixed charge of 1.3μC. The electron is moved from the positive charge to 4.0 cm away from the charge. If the electron is released from the 4.0 c mark, what is the max velocity of the electron? Homework...
  16. E

    Deriving a volume formula, answer seems to be correct but is negative.

    I'm an engineering student, and I'm making a formula for the volume of liquid in a cylinder that is cut in half diagonally. r is the radius, h is the height from the bottom to the top of the sloped flat bottom, and L is the height of the water within the cylinder. So when L = h you would expect...
  17. F

    Is there a negative stigma with applied physics

    I'm currently a physics major. I plan to study robotics engineering in grad school (haven't decided if I'll do it through ME, EE, CS, or a robotics specific program). I've recently realized, though, that if I change my major to applied physics, I'll be able to take electives that will be more...
  18. 2

    Negative sign when finding forces from derivative of potential?

    Hi! I'm currently reading a book where they give the Coulomb potential, gravitational potential and harmonic potential as +Q1Q2/4∏εx -Gm1m2/x +(1/2)qx2 I think I get the signs as they are used here, but when I am trying to find the force by taking the derivative of these with respect...
  19. D

    Negative Poisson-Binomial Distribution

    The name in the title is probably not what it's called but it so similar that I chose it anyways. This is a problem I've been looking into on my spare time and I'm having a difficult time nailing it down. Essentially, it's an "extension" of the negative binomial distribution in the sense that...
  20. PhysicsStudnt

    Is there a difference between negative acceleration and retardation

    Kindly elaborate on the difference between negative acceleration and retardation...if they are different
  21. L

    How can Voltage have polarity? How can they be negative or positive?

    Voltage is potential difference between two terminals of a power source that causes the electrons to flow, right? How can that be positive or negative? What is positive voltage and what is negative voltage? Thank you,
  22. S

    [Signals and Systems] What's the signinfance of negative time?

    Hello all, This one thought came to my mind just now. What's the physical significance of signal representation in negative time, i mean second and third quadrant. So for example, sin(t) and sin(t).u(t) aren't they same for all practical purposes? I know, mathematically they are...
  23. N

    Why negative Rockwell Hardness value is considered as "no good"?

    I have read some pdf files and it says negative Rockwell hardness value is not used because of it would cause confusion. What I currently know is : HR(C/B) = N - h/s; for C scale, N = 130; while for B scale N = 100; s always = 0.002 and h is the permanent depth of the indentation...
  24. A

    Question about an Alcubierre warp drive's negative energy requirement

    I've been reading Dr. Harold G. White's work on recent developments in Warp Field Mechanics, and thought up the following question: Could a proof of the Alcubierre warp drive concept be made by using a warp bubble energy differential whose flat-space energy density level was positively offset...
  25. A

    Can the electric potential be negative ?

    I have just solved a problem about electric potential and it is: " A positive point charge of 1.0 nC is located at position x=0.00 . A second point charge q=-1.0 nC is located at x=0.10 m. (a) What is the value of the electric potential on the x-axis at x=0.3 m ? (b) What is the value of the...
  26. D

    Exploring Negative Binding Energy: Examples & Explanations

    What is binding energy? Give two examples. Most forms of energy are positive. Why is binding energy negative?
  27. ecoo

    Why Does Raising a Negative Number to a Power Yield a Negative Result?

    How come when you do something like -3^2=-9. Does it mean that the dash is a subtraction symbol and not a negative symbol?
  28. G

    How Does the Additional Electron in (O2)- Affect Its Paramagnetism?

    O2 has two unpaired electrons, therefore it's quite strong paramagnetism. But what about (O2)-, the negatively charged O2 ion? Am I right in assuming that due to the additional electron one unpaired electron will get together with it, so that overall it should still be paramagnetic, but...
  29. N

    Two isolated metal cubes: Negative ΔS? Thermodynamics

    Hi. So let's say you have two identical cubes with expansion coefficients of approx. zero. These cubes are thermally in contact with each other, and otherwise isolated from the surroundings. One cube has a higher temperature than the other, so heat will flow from the hotter cube and to the...
  30. A

    Why is potential energy considered negative in an inversed pendulum system?

    we have an inversed pendulum(ignore the car) and we choose the coordinate system to be upwards the potential energy PE=mgz (z will be hegative since( O,k) is upwards right?) z is always under O. but in the textbook they basically take the absolute value of h i don't understand why?
  31. K

    Electric Field with three negative point charges in a line

    Homework Statement Find the magnitude of the electric field this comination of charges produces at point P, which lies 6.00cm from the -2.00μC charge measured perpendicular to the line connecting the three charges. Homework Equations E=k\frac{Q}{r^{2}} F=k\frac{q_{1}q_{2}}{r^{2}}...
  32. I

    Are electrons negative by default?

    Are electrons negative to anything? Did we notice two different charges and decide to label them like we did with left and right? I'm very curious to know why we brand electrons as negatively charged.
  33. F

    Negative values in calibration curve

    Hi I just wondering how to report negative values cuased by non-zero intersection. For example, when the absorbance<0.037 in the figure, the concentration would be negative. Thank you!
  34. S

    How to understand the negative two-photon transition strength

    Dear all, I have calculated the rotationally averaged two-photon transition strength (DeltaTPA) using the CCSD response approach. Degenerate TPAs of ten excited states have been calculated. For most of the excited states considered, I got the positive DeltaTPAs, while for some excited states...
  35. F

    Unsensible Rules/Laws of negative number operations

    First of all I must make a claim. Rules are shortcuts. Shortcuts that people use to not bother in understanding the complete picture of something. And this includes the rules of calculation between negative and positive numbers. Furthermore, I believe that these rules are counterintuitive or...
  36. G

    Bound States, Negative Potential, Alternate Basis, Matrix Mechanics

    Homework Statement Given the potential V(x) = - 1/ sqrt(1+x^2) Consider this in a 50x50 matrix representation of the hamiltonian in the basis of a one dimensional harmonic oscillator. Determine the eigenvalues and eigenvecotrs, the optimal parameter for the basis, and cop ate the...
  37. G

    Bound state negative potentials into harmonic oscillator basis

    Hello readers, Given the potential V(x) = - 1/ sqrt(1+x^2) I have found numerically 12 negative energy solutions Now I want to try to solve for these using matrix mechanics I know the matrix form of the harmonic oscillator operators X_ho, P_ho. I believe I need to perform the...
  38. T

    Do I Need to Include Minus Signs in Energy Conservation Equations?

    Hi All, I just have a question regarding potential energies. Say I have a block above a spring, and I define the potential energy of gravity and the spring to be zero at the uncompressed point. I then drop the block, trying to find the maximum compression of the spring using conservation of...
  39. N

    What happens to the negative charge

    A negative charge -q is placed at the origin. Two positive charge of +4q are on both sides of the negative charge at distance d. what happens?
  40. S

    Negative Force-potential energy relationship?

    I've been wondering for a while why force is the negative derivative of potential energy. In our books, they write that F=-dU/dx, and U=-W I don't really understand why it should be negative. Doesn't the force need to be positive in order to increase the potential energy? For example, when you...
  41. D

    Negative refraction, meta materials, no quest for chemists?

    Recently, I have read a lot about the physics behind negative refraction, super lenses, meta-materials and the like and I think I understood the theory to quite some detail. Negative refraction was predicted first by sowiet physicists around Mandelshtam [1,2], and, a paper by Veselago [3,4]...
  42. J

    Do Positive Numbers Necessitate the Existence of Their Negative Counterparts?

    If counting/positive numbers exist, do they imply the existence of negative numbers? I'd say yes, because there's always a bijection that maps the lowest counting number of the set to the highest, then the second lowest to the second highest, etc. This reversal of order/mirroring is possible...
  43. M

    How to determine negative ambient pressure?

    hello! which methods are available to determine (negative) ambient pressure? for example, I want to check the pressure inside a plastic see-through box can I send a beam of laser, an ultrasound, or something else to determine it? thanks!
  44. G

    How are negative ions created in an experiment with a balloon and wool?

    In a famous experiment with a balloon and wool. http://phet.colorado.edu/sims/html/balloons-and-static-electricity/latest/balloons-and-static-electricity_en.html Initially the balloon and wool pullover have no ions. I understand how positive ions are formed, that you apply energy to the...
  45. C

    Negative work, positive work problems

    Example 23.2 in University Physics of Young and Freedman, i have a confusion with Negative work, positive work In question b, Why the external force does a negative work (as i know, when you put three charges from infinity to the point of need identified, we will always do a force has the same...
  46. anemone

    MHB Finding $q$ in a Polynomial with Negative Integer Roots

    If $P(x)=x^4+mx^3+nx^2+px+q$ is a polynomial whose roots are all negative integers, and given that $m+n+p+q=2009$, find $q$.
  47. E

    Dot Product of a Unit Vector with the Negative of itself

    Homework Statement I am trying to calculate the flux for the octant of a sphere, and I am trying to figure out how the mathematics, dot products, and dA works in the integral. I already did the quadrant for \hat{θ} where θ= π/2 (the bottom quadrant) and I did the left quadrant where \hat{n}...
  48. E

    Can a dot product be negative in case of length?

    Let's say A and B are 2 vectors with length in cm and the angle between them is 170°. Obviously, the dot product of A and B will give cm2 as unit but since the value of cos(170) is negative, will the dot product be negative (something)cm2?
  49. K

    Negative pressure head in a nozzle

    Hi, I am doing some fluid flow calculations for some nozzle designs at work. For one nozzle in particular, the fluid flows through an inlet pipe, then flows through a short contracted section, then flows into a Helmholtz chamber before entering another contracted section through which it...
  50. baby_1

    Negative sign in voltage equation

    hello as we know if we wanta find the resistance of a material we use this equation but in electromagnetic course we know that voltage equation has negative sign that it is refer to positive charge thas positive sing and negative charge has negative sing . why in resistance...
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