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. M

    What does it mean to have a negative change in current?

    Does a di/dt<0 mean an increasing current moving from a lower potential to a higher potential (if we define the direction of current to be the flow of the positive charges)? Similar question with negative current i.e.; dq/dt<0.
  2. P

    When should I consider the sign of charges when applying Coulomb's Law?

    I am studying Physics Vol2 by halliday, resnick and krane. I was attempting the coloumb force exercises..If we put one charge negative and other positive in the formula..then the force comes out to be negative but the instructor manual for the book ignores the negative charge, and take it as...
  3. S

    Negative energy eigenvalues of Hamiltonian

    Homework Statement If I have a Hamiltonian matrix, \mathcal{H}, that only depends on a kinetic energy operator, do the energy eigenvalues have to be non-negative? I have an \mathcal{H} like this, and some of its eigenvalues are negative, so I was wondering if they have any physical...
  4. L

    Why Is Lowering a Box Considered Negative Work While Gravity Does Positive?

    Homework Statement How come A person picks a 1.00-kg box of macaroni from off the shelf and lowers it 0.77 m into a shopping cart. The work done on the macaroni by the person is negative work however when person picks up a 1.00-kg box of macaroni from off the shelf and lowers it 0.77 m into a...
  5. K

    Fxy in a contour graph, positive or negative?

    Homework Statement d=1352846320 The question asks for fxy. The rate of change of (the rate of change of f in the x direction) in the y-direction. We know fx is negative because as f moves in the x-direction, f decreases. But how do I know the rate of change of fx in the...
  6. C

    Statistical mechanics with a negative amount of atoms

    My advanced statistical mechanics prof told me that it wouldn't make any physical sense to allow N (the number of particles in a system) to be negative. But, somehow, I think that this possibility should be theoretically left open; perhaps there are some systems whose statistical behavior would...
  7. K

    Op amps, negative feedback or not?

    Homework Statement What is the exact definition of negative feedback? the instructor told us that negative exists if the output is connected back to the inverting input through a passive element. But what exactly is precise the definition ? (say parallel connect, same two nodes, I want the...
  8. M

    Why Can Tangential Acceleration Vector's Scalar Component Not Be Negative?

    we already know that the scalar component of the Centripetal ( Radial ) Acceleration vector is always negative because it's ALWAYS directed to the opposite direction of its unit vector ( toward the center of the circle ) , and this is satisfying to me and to the formula . however , when it...
  9. E

    Expanding parenthesis when a negative is involved

    Im completing Engineering Maths cover to cover in an attempt to get more familiar with maths as I finished my education many years ago without really understanding many basic maths concepts. This problem is at the back of the introduction to algebra. (x-2y)^2 - (2x - y)^2 Now I can expand...
  10. O

    Consequences of a negative mass universe

    If a universe existed where all the mass was negative but everything else was the same as our universe in terms laws of physics what would happen? To be more specific it appears that all the mass would repel each other, would negative mass atoms form, would these particles absorb or emit light...
  11. L

    Limit approaching negative infinity

    lim x( (x2 −2x+5)^(1/2)−|x−1|) x→−∞ so far, the only way I have started the question is by multiplying for the conjugate but i cannot get it to simply to the answer which is -2 after that step.
  12. tomwilliam2

    Is the Work Done by the Electric Field Positive or Negative?

    Homework Statement How much work is done by the electric field in moving a particle from (a,a,0) to (a,a,a) in a region where the electric field is: E = zye_x + yxey + xyezHomework Equations F=qE W = integral F dot dl V(2)-V(1)= - integral E dot dl The Attempt at a Solution I know how to do...
  13. I

    Phase portrait for a conservative negative potential

    Hi, i was studying Classical Mechanics course introduced by the brilliant Prof. V. Balakrishnan he was studying the phase portrait of a simple harmonic oscillator in one dimension , where the total enegry of the system is E=\frac{1}{2}m\dot{q}^{2}+\frac{1}{2}mω^{2}q^{2} where E is constant...
  14. PhizKid

    Why is weight positive if gravity is negative?

    Homework Statement Why is weight positive if gravity is negative? Homework Equations W = mg The Attempt at a Solution So say there is some weight of an object, and the object's mass is multiplied by the acceleration due to gravity pointing downwards, so the weight becomes negative...
  15. Z

    Can negative particles attract each other

    My first post so please forgive me if I am already breaking some rules ;) This may apply to positive or negative particles: We know that equal charges repel each other to the value of Coulomb force F=kqq/r^2. What I would like to know is if a magnetic force between two (non-moving, but...
  16. J

    What is negative mechanical Power?

    Homework Statement In terms of mechanics, does negative Work produce negative Power? If so, what is negative mechanical Power? Homework Equations W=F*d P=W/t The Attempt at a Solution I know if a car is rolling downhill and I try to push against it, but I end up getting pushed...
  17. C

    Can decreasing acceleration be negative acceleration ?

    Can decreasing acceleration be negative acceleration ?
  18. D

    Question regarding Negative Velocity

    On a Position-Time Graph, if you start with a negative velocity and slowly increase (Accelerate) in velocity, would you have a negative position that increases to a positive position? In other words, would it look like this? Velocity-Time Graph on the Right, Position Time-Graph on...
  19. C

    What Are Negative Energies in System ψ?

    Lets say I have a system ψ with a Hamiltonian matrix H and energy eigenvalues E. Just a general system, with no particular basis given. When I solve the eigenvalue equation for H, and get zero or negative numbers or zero for E, is that physical? If it is not physical, do the negative numbers or...
  20. S

    Factorial of a negative number

    Is it possible to find the factorial of a negative real number ? If possible, then what is its practical application ?
  21. H

    What Does n^{-1} Really Represent in Mathematical Terms?

    Homework Statement The problem is stated in the attempt as a solution Homework Equations There are none The Attempt at a Solution Suppose you have n^{-1} am I right in thinking this is just \frac{n}{1} so for something like n^{-2} would it be simply \frac{n}{2}?
  22. K

    Why Did the Negative Sign Disappear in the Calculus Example?

    http://math.colorado.edu/~jkeller/math1300/lectures/L8limits3.pdf Example 8, the 2nd to 3rd step... where did the negative go? It's (x^2 - 3x) - x^2 then it became 3x in the numerator. Where'd the negative go? I don't see any other sign changes so could someone please tell me?
  23. J

    Gamma Function Limits: Proving \Gamma(x) \to 0 as x \to -\infty

    Homework Statement The absolute value of the gamma function \Gamma (x) that is defined on the negative real axis tends to zero as x \to - \infty . Right? But how do I prove it? Homework Equations The Attempt at a Solution I've tried to use Gauss's Formula...
  24. P

    Negative number multiplied by a negative number

    For two positive numbers such as 5 and 3 their multiplication results in a positive number because it is 5 times 3 or 3 times 5 (5+5+5) also when we multiply a negative number with a positive number say -5x3 i.e 3 times negative 5 will give us (-5+-5+-5) but now what is the explanation for a...
  25. L

    Epsilon-delta proof of linear eq. with negative slope

    I am familiar with most of how to do ε-δ proofs (even though our professor thought it unimportant to teach it, and our book kind of glosses over it (Larson, Fundamentals of Calculus, 9th), even quadratically, but for some reason I am just getting stuck on what is probably a simple problem...
  26. S

    Simplifying with rational and negative exponents

    Homework Statement Simplify the expression completely 3(y)(1/3)-3x(y)(-2/3)(2x) / [(y)(1/3)]2 The Attempt at a Solution My attempt is totally wrong. I can't quit figure out what to do or where to start 3(y)(1/3)-3x(y)(-2/3)(2x) / [(y)(1/3)]2 3(y)(1/3)-6x(y)(-2/3) / y(2/3)...
  27. B

    Does Lifting a Block Involve Negative Work on You?

    Unfortunately I still have not completely grasped the idea of negative work. I appreciate all the help in understanding this concept! Suppose that you lift a block of mass M an upwards distance of D. The force you applied on the block is a constant F directed parallel to the displacement of the...
  28. B

    Question about the significance of negative work

    I am having some trouble understanding the significance of negative work. If the work that I do on object X is W, is it equivalent to saying that object X does work on me equal to -W ? After all, work is scalar, so I can't fathom the physical significance of negative work. Also...
  29. Z

    Are Negative Angles Important in Geometry?

    Hi everybody; I am a bit stuck with negative angles. What I know is that: If we measure an angle from x-axis clockwise direction, the angle is negative. However, I am a bit dissapointed because while I researched the web I see the negative agles only in topics subject to trigonometry. So I...
  30. L

    Dependent sources - can the gain (g) be negative?

    So the goal in this case is to find k, the gain of the dependent source shown as a diamond. Formula for dependent voltage sources: V=g*V0 In this case V=k*Va I would get a negative value for k, because k=V/Va=-10V/(0.2A*10Ω)=-5 But can you have a negative value for k? Is that possible? Or...
  31. G

    Maximum Power Transfer with Negative Thevenin Resistance?

    Hello everyone! I have a general question about how to find out the maximum power transfer to a load resistor with a negative Thevenin Resistance (Rth < 0). I know for positive cases, P = R*(Vth/(R + Rth))^2, in which R is the load resistor connected to the Thevenin equivalence circuit, and Pmax...
  32. P

    Electric Potential - Work: Negative or Positive

    Hi guys, So, these two formulas are making me very confused: UE=kQq/r ΔUE=-WE Ok, here is the problem: Let's imagine that we have two positive charges. One of them is static, the other one can move. If we place the positive charge close to the source charge, the movable...
  33. J

    Can you have a negative average velocity?

    I understand that it's possible to have a negative instantaneous velocity, but I'm wondering if it's possible to have an negative average velocity. For example, let's say you start heading north at a constant 10 mph for an hour. The second hour, you drive south (directly toward the starting...
  34. B

    Why does inverting the base of a negative exponent cancel the negative?

    So I understand the math, that is, how to solve these problems. But how does inverting the base cancel out the negative in the exponent? I worked out inversion to simply be a setback of 2 decimal places, e.g. 12.5% of 8 = 1, so 1/8 is .125 % of 1. But why does this nullify the negative?
  35. Z

    Fractional Exponent of Negative Numbers

    I have been thinking on this topic for a while. As I have seen on various sites: 1) a^(b/c) means "c"th root of "a^b". 2) Also an even root of a negative number does not exist in real numbers. Then I want to investigate this formula: a=(-4)^(1/2) Mustn't it be equal to...
  36. L

    Plot Negative Axis Upward in Origin - Q&A

    Not sure if this is the right place to post it. Does anyone know how to plot negative axis upwards on Origin?
  37. B

    Negative Ion Emission: Heat, Piezoelectric Effect & Object Differences

    Will more negative ions emit from an object (like a "negative ion generator") due to heat or piezoelectric effect or will they emit any way? Also, do certain objects give off more negative ions than others?
  38. H

    Automotive Very high value of negative camber angle

    I was wondering that what will happen to a car which has a negative camber angle of over 45 degrees, will it make impossible to even move or it is possible if we design special tires for the same..? i know it will be almost impossible to steer such a vehicle but i want to know what is the...
  39. M

    Why do attractive force have a negative sign? like F= -GMm/r^2

    Why do attractive force have a negative sign? The book says its because one must be moving toward the other. But how does it make it negative? I don't understand. Can anyone explain the law of gravitation formula?? F= -GMm/r^2
  40. O

    Negative feedback - Open loop gain question

    This is my first post here. I'm currently learning about Negative feedback. Normally, When we want to know the open loop gain, we rewrite circuit(a) to circuit(b). My question is why do RE1,RF,RE2 from circuit(a) turn into what we see circuit(b)? what is a theory behind this? In...
  41. J

    MHB Integral from negative infinity to infinity

    $\displaystyle (1)\;\; \int_{-\infty}^{\infty}\frac{x^2}{1+4x+3x^2-4x^3-2x^4+2x^5+x^6}dx$
  42. T

    Negative determinants when calculating eigenvectors?

    Let M be a transformation matrix. C is the matrix which diagonalizes M. I'm trying to use the formula D = C-1MC. I noticed that depending on how I arrange my vectors in C, I can change the sign of the determinant. If I calculate D using a configuration of C that gives me a negative value for...
  43. S

    Negative Work but Average Force positive in this situation?

    I just want to make sure I'm understanding negative work correctly. An example problem where there is a bullet with an initial velocity of x m/s and a final velocity of 0 m/s. It is stopped by a wood block and the question asks to determine the amount of work done on the bullet by the block. If...
  44. L

    Stirling's approximation for Gamma functions with a negative argument

    Hi, fellow physicists (to be). This is my first post on the forum, so I hope I get it right. If not so, please let me know :) introduction to the problem At the moment I am working on my physics bachelor's thesis at the theoretical department of my university (Amsterdam). My thesis focusses...
  45. A

    Why isn't 80 mod (-11) equal to 3?

    Can someone please explain why 80 mod (-11) is -8…? Why isn’t it 3? b = aq + r 80 = (-11)q + r 80 = (-11)(-7) + 3 Thus 80 mod (-11) = 3..
  46. nomadreid

    Negative energy: same in Casimir, Hawking rad, & spherical space?

    The term "negative energy" is used (a) for the energy below the vacuum energy between the two plates in the Casimir effect, (b) the energy carried by the sister particle to the radiated particle in Hawking radiation, that is, the particle from the matter-antimatter pair which goes into the...
  47. P

    How do I multiply positive and negative numbers? (in n's complement)

    Homework Statement I need to understand how signed multiplication is done in 2's to 10's complement.Homework Equations The complement D' of a number D with m digits in base r is rm - D. So, the complement of 010 in binary (2 in dec) is 1000 - 010 = 110 (-2, but 6 if it were unsigned). We add a...
  48. J

    Negative Work: What Does it Mean?

    In my textbook there is given an example of a person holding a chair for three minutes. The persons arm gets tired but no work is done because there is no displacement. In the sidebar of my textbook, there is this note: "We can calculate the work done by a force on an object, but that...
  49. A

    Intuition for positive, negative, and ground voltage

    Can anyone help me develop some insight as to what positive and negative voltage means? I've heard of the analogy to water flowing where amps are viewed as units of water flowing through a certain point per unit time and volts are viewed as how high the water is flowing downwards to the...
  50. andrewkirk

    Why is a gravitational field negative energy ?

    Why is a gravitational field "negative energy"? The idea about the universe having zero net energy, as explained for instance in http://en.wikipedia.org/wiki/Zero-energy_universe, seems to be that gravity has 'negative energy', which offsets the positive energy of all the matter and radiation...
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