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. donaldparida

    B Difference between W=-(ΔU) and negative U.

    Is there any difference between the meaning of the equation W=-ΔU and the meaning of the statement that potential energy of system is always negative when the reference point(zero point) is taken to be located at infinity or do they both convey the same message?
  2. C

    B Can Cosmological Constant contract (negative)?

    Hello... Can the cosmological constant become so rigid as to resist the 120 magnitude quantum contribution? Where is the mathematical terms for it in GR EFEs? is the effect like contraction instead of expansion? Because the 120 magnitude quantum contribution should immediately warp spacetime...
  3. Pallta

    How do I know when velocity is negative in a 1-D motion problem?

    Homework Statement Two baseballs are set in motion from the top of a 5 m tall tower. One is thrown straight down toward the ground with an initial velocity of 20 m/s. The second is thrown straight up toward the sky with an initial velocity of 20 m/s. How do their velocities compare when they...
  4. G

    I Why Is Negative Magnetoresistance Possible in Dilute Magnetic Alloys?

    A free electron gas would have zero magnetoresistance; it takes two carrier types to get ordinary magnetoresistance, which is always positive in sign. Beal-Monod and Weiner explain the negative magnetoresistance found in very dilute magnetic alloys, in terms of the spin-flip scattering of...
  5. T

    Carnot Cycle with negative temperatures

    Homework Statement Heat engines at negative temperatures. Consider using two heat reservoirs to run an engine (analogous to the Carnot cycle of chapter 3), but specify that both temperatures, T_hot and T_cold, are negative temperatures. The engine is to run reversibly. (a) If the engine is to...
  6. P

    Exploring the Concept of Negative Weight and its Effects on the Human Body

    I have read that the apparent weight of a person in a lift accelerating with acceleration 'a' downwards is given by: W = m(g-a) where 'm' is his mass so if a>g, then one feels negative apparent weight. But, it is also true that one becomes conscious of his weight only when he gets a reaction...
  7. xortan

    Attaching AC Earth to DC Negative

    Hello everyone, So I am doing this EMC course and got to a section about cable shielding. It was suggested that the best way is to have a 360 connection to the chassis and to connect the ground of the PCB to the chassis as to provide a better return path for the current. It has been suggested...
  8. B

    B Does physics allow us to create large amounts of negative energy?

    Hello. Casimir effect allows to create negative-energy-density (NED), but ONLY SMALL AMOUNTS of it. I wonder if physics generally allows for the existence of negative energy in large quantities. I think that if the negative energy can be produced in small quantities, it can also occur in larger...
  9. Mr Davis 97

    B No distinction between positive and negative for imag nums?

    I am solving for the square root of a complex number, namely: ##\sqrt{5 -12i}## Let's assume for brevity's sake that I already have the solution ##3- 2i##. This is fine and well, but the book that I am reading goes on to say that "##- (3 -2i)## is an equally valid solution, since there is no...
  10. Shafia Zahin

    B Why does an attractive force always have a negative sign?

    I've seen in many equations of physics that whenever we demonstrate an attraction force we tend to use a negative sign before it,why is that? In case of coulomb force it makes sense because when the charged particles are of opposite signs a negative sign is sure to be appeared.But why do we...
  11. akashpandey

    I Why Do Opposite Charges Attract?

    I know its very basic but still. From the school level we thaught that positive attracts negative. But i still don't know what is reason behind it. Why this work on atomic level? What is the reason behind the electrostatic attraction?
  12. L

    Getting 'negative' force when calculating drag

    I'm trying to add flight physics to a 3d game. When I try to calculate drag I sometimes get a force that pushes the aircraft backwards if I make the wingspan very large (for example). I have set up a simple scenario: A flat rectangle sheet falling down due to gravity. If I make the gravity...
  13. F

    I Feynman Lectures: negative alpha for solving Schrödinger equation

    Why doesn't The Feynman Lectures consider the possibility of negative ##\alpha## when it says that ##e^{+2\alpha\rho}## is a rapidly increasing exponential (just below http://feynmanlectures.caltech.edu/III_19.html#mjx-eqn-EqIII1923) ?
  14. Borrah Campbell

    Build a Low-Voltage Negative Ion Generator w/ AA Batteries

    Howdy! How do I build a small low-voltage ion generator? The simplest possible design; we'er talking AA batteries here with step-by-step instructions... Any links or advice would be graciously accepted / appreciated. Here is a youtube video of the thing I want in case I'm not describing it...
  15. Y

    How to understand negative frequency?

    Recently I learned some communication theory, which uses negative frequency, what does negative frequency means? So I checked textbook, found the negative frequency comes from the Fourier transform, which comes from the euler formula, e-jx=cosx+isinx, or another form cosx=(ejx+e-jx)/2, then any...
  16. T

    Which reaction will have a negative ∆H value

    Homework Statement Homework EquationsThe Attempt at a Solution Negative ∆H means that the product is more stable. Change from solid to gas requires energy so cancel out A and C. Reaction D doesn't make sense. The products of reaction B and E are more stable than the reactant because there is...
  17. cnh1995

    Rotor and negative sequence impedance of alternator

    When an alternator is supplied with a 3-phase voltage and its rotor is rotated in opposite direction to that of the stator rmf, the ratio phase voltage/phase current is the negative sequence impedance of the alternator. My understanding of this is as follows: When rotor is rotated in opposite...
  18. M

    Negative index of refraction transmission

    Hi guys, I read a lots of papers about this theme, but still I don't understand what is going on. I have slab of negative index of refraction material, inside the material the evanescence field is amplified. I want to calculate transmission of this slab for evanescence waves, so I used fresnel...
  19. 1

    Why does the point experience NEGATIVE field strength?

    Hi, i'm looking for an explanation to this answer of a past paper that I'm doing, it's from OCR (A level) G485, question 1 b ii) the question on top, and answer on bottom i don't understand why would the point experience a negative electric field strength when it's getting closer to a...
  20. JR Sauerland

    B Why did they change the sign to be negative?

    http://imgur.com/BNQPAQa I'm missing something. Why does x+1/x suddenly become x-1/x2? I get that they moved the x to the top, subtracted the -1-1, but does that exclusively set the fraction negative all on its own ? I've computed it by hand. 1-2 comes out to be 1... So why is it negative... ?
  21. C

    Electric Field question - Why is this answer negative

    Hello. The first image is the question, the second image is from the solutions manual. I don't understand why these answers are negative. Anyone have a clue?
  22. G

    Negative Buckling: What Are the Conditions?

    Under what conditions would negative buckling (B^2) be possible?
  23. Mouadys

    Hooke's Law: Spring Force Negative?

    Hello, Following Hooke's law, the force applied by a string on an object attached to one of its ends is F = -kx But here is my question : if we consider the equilibrium coordinate x=0 of a horizontal string, and the string is stretched until its end reaches a coordinate x1>0. By applying hooke's...
  24. cnh1995

    Negative sequence currents in an alternator

    We recently performed one experiment regarding measurement of negative sequence impedance of an alternator(unloaded) in our lab session. The alternator was star connected and we shorted Y and B phases together, leaving R phase open(an L-L fault). How does this arrangement generate negative...
  25. Cosmology2015

    I Energy Locally Never Negative: Explained

    Hello to all members! I heard on a documentary about general relativity and singularities that "energy is locally never negative". However, I was not able to get grasp the meaning of this term. Could someone explain to me the meaning of this term in the framework of general relativity. I really...
  26. D

    The negative charge of the Earth

    The Earth has a net negative charge whilst the Ionosphere has a net positive charge, this has been known for well over a hundred years now. My question is about the negative charge of the Earth, are the free electrons on the Earth's surface stationary? are they whizzing around in the Earth in...
  27. S

    B Exploring Negative Energy in the Universe: Examples, Evidence, and Impact

    Hawking and others have claimed that there's a negative energy associated with gravitation that makes the universe's total energy balance -- including all the energy in all the mass in all the matter in the universe -- zero. But there was no such thing as negative energy in any type of physics...
  28. T

    MHB Linked list negative values counting.

    I am having trouble with this program with negativeCntr . Any one explain what i am doing wrong and guide me please. [CODE]#include <iostream> #include <cstdlib> using namespace std; class IntNode { public: IntNode(int dataInit = 0, IntNode* nextLoc = 0); void InsertAfter(IntNode*...
  29. E

    Pseudo forces and negative acceleration

    Homework Statement Homework Equations F = ma The Attempt at a Solution [/B] I already have the solution, however, I have a few questions. 1)In the solution they have taken m2's acceleration relative to the ground to be a0-a downwards. However, if a>a0, then wouldn't the acceleration...
  30. Dan15

    I How does negative power link to amplification?

    So I've been studying electrons behavior in a semiconductor superlattice and I am currently analyzing the negative slope for the drift velocity against electric field. This is where negative differential velocity (NDV) takes place. I understand how NDV leads to negative power, but I can't quite...
  31. NatFex

    I Proving De Moivre's Theorem for Negative Numbers?

    Or basically anything that isn't a positive integer. So I can prove quite easily by induction that for any integer n>0, De Moivre's Theorem (below) holds. If ##\DeclareMathOperator\cis{cis} z = r\cis\theta, z^n= r^n\cis(n\theta)## My proof below: However I struggle to do this with...
  32. Marcin H

    Audio Amp with negative feedback

    Homework Statement Homework Equations The Attempt at a Solution I am not really sure how to do this problem. How can I convert from db to linear terms just given db? Don't I need more information? For do I have to do a system of equations or something using the Power gain =...
  33. K

    Why lungs have more negative intrapleural pressure at the apex

    in some books it is written that it is because of gravity but i can't understand how gravity can cause such a effect
  34. D

    I Proving Zero is Positive or Negative

    Good morning, How do we prove that the number zero is a negative or positive number?
  35. C

    Exploring Negative Refraction in Lenses and its Effects on Visual Perception

    https://en.wikipedia.org/wiki/Negative_refraction http://www.cmth.ph.ic.ac.uk/photonics/Newphotonics/pdf/DRS&JBP_final_.pdf Supposed the nature of light is altered and light itself cause negative refractive index in normal lenses.. what would we see with our eyes, lenses, binoculars? What...
  36. T

    What's the Difference Between Positive and Negative?

    I am aware of what positive and negative polarities are but what specifically causes the distinction between positive and negative polarity?
  37. L

    Why does heat engine need to do negative work to surround?

    Every thermodynamics cycle needs to do negative work to the environment, which lower its total positive work. For example, in Carnot cycle, the most efficiency possible: 1/ Engine receives heat from hot reservoir, expands and do positive work to surround 2/ Surround does work to engine...
  38. S

    B Integrating velocity equation problem

    I've already completed the first question, but with number two, it's a different case. Here's my attempt: \frac { d{ v }_{ y } }{ dt } \quad =\quad -g\quad -\quad \beta { v }_{ y }\\ \frac { d{ v }_{ y } }{ -g\quad -\quad \beta { v }_{ y } } \quad =\quad dt\\ \int { \frac { d{ v }_{ y } }{...
  39. S

    MHB Pattern description: powers of a negative number

    Given the following pattern. $$(-1)^{0}=1$$ $$(-1)^{1}=-1$$ $$(-1)^{2}=1$$ $$(-1)^{3}=-1$$ $$(-1)^{4}=1$$ $$(-1)^{5}=-1$$ $$(-1)^{6}=1$$ $$(-1)^{7}=-1$$ $$\ldots$$ In words, we might say that the power of a negative number is: Positive for even exponents. Negative for odd exponents. How...
  40. kiwaho

    I Why to use negative hydrogen in spallation neutron source?

    Just wondering why to use negative hydrogen H- ion in spallation neutron source. I read the literature through http://neutrons2.ornl.gov/facilities/SNS/works.shtml , still not yet get the answer. If directly use proton, then still easy to accelerate, and no need to strip off the unwanted...
  41. Mohummed Kazmi

    Negative values of magnetic fields strength obtained?

    Homework Statement We were asked to use a Hall probe (in units of Guass) to measure the magnetic field strength in 0.5 cm increments away from a wire carrying 4 A of current. As we got further and further away from the wire our B value got smaller and smaller. Eventually they became negative...
  42. Blockade

    B Why is there a negative in Hooke's Law (F = -kx)

    For Hooke's Law, why is there a negative in F = -k*x? Is it because k is the reaction force against the force applied on the spring and not the force pushing or pulling on it? For example, let's say that the origin is set where the spring ends when it's in equilibrium with no forces applied to...
  43. S

    I Why is the KE operator negative in QM?

    In the Hamilonian for an H2+, the kinetic energy of the electron (KE of nucleus ignored due to born-oppenheimer approximation) has a negative sign in front of it. I understand the signs for the potential energy operators but not for the KE apart from the strictly mathematical point of view. Can...
  44. firefox

    Negative Moment of Inertia from Atwood Machine Experiment?

    I'm currently completing an Atwood Machine Experiment with two 100g weights on either side of the pulley, with a variance in weight created by attaching dimes and pennies to either side of the weights. The point of the experiment is to validate: (m1 – m2)g = (m1 + m2 + I/R2) Homework Statement...
  45. Tollendal

    Negative absolute temperatures

    https://www.mpg.de/research/negative-absolute-temperature A temperature below absolute zero Atoms at negative absolute temperature are the hottest systems in the world January 4, 2013 What is normal to most people in winter has so far been impossible in physics: a minus temperature. On the...
  46. P

    I Conditions on negative definiteness

    Hello, I want to know if there exist any result in literature that answers my question: Under which conditions on the real valued matrix ## R ## (symmetric positive definite), the first argument results in and guarantees the second one: 1) for real valued matrices ##A, B, C,## and ## D ## with...
  47. J Mc

    In a DC circuit, is "negative" synonymous with "neutral"?

    Hi, I'll start by offering some context to my question. I am a mechanic by trade, and have a bachelor of technology in motorsport engineering. I have a friend who is an electrician by trade, and he likes to work on his car in his spare time. In my line of work I only deal with 12V/24VDC...
  48. T

    How does an Op-Amp "find" equilibrium (w/ Negative Feedback)?

    Hi everyone, I've been seeking the answer to this question for a long time. I've looked at posts like... https://www.physicsforums.com/threads/op-amp-transient-state.855512/ and https://www.physicsforums.com/threads/how-does-negative-feedback-in-an-op-amp-work-conceptually.584881/ ...but I...
  49. EB3 Effects

    Negative bouyancy/sinking a car

    Hello all and thanks in advance for your contributions. I am calculating how much weight it will take to keep a car on the floor of a 5' deep pool. The engine and transmission have been removed as well as the hood and trunk. The remaining body weighs 2,000 lb. The cab will be sealed air...
  50. Drakkith

    Negative and Positive E-Field Components

    Homework Statement In the diagram below, each division on the horizontal axis (the displacement s) is 0.10 m while each division on the vertical axis (the electric potential V) is 1.0 V. What is the electric field component along the displacement axis s in each of the regions specified below...
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