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. pete94857

    I Calculating Watt Hours for a time interval less than 1 second

    I use an online physics calculator a lot to help me for various reasons. When I input less than 1 second into a watt hour calculation it initially tells me it can not be a negative value although that does disappear and it does do the calculation. Example power 10 w time 0.01 seconds 0.1 J...
  2. A

    What happens if a negative pressure gradient is applied to a diffuser?

    A diffuser normally decreases the velocity by increasing the area. With assumption of an incrompressible flow, according to Bernoulli, the static pressure increases. What happens if one "forces" the flow through a diffuser by applying a bigger pressure on the inlet than on the outlet?
  3. M

    Missing negative sign in my textbook's answer?

    the question is fairly easy to solve, integrating ##NiAB sin(\theta)## from ##\pi## to 0 or just do ##-NiAB(cos(0) - cos(\pi))## which gives you -2NiAB, but my textbook did not include the negative sign, is it mistaken?
  4. tellmesomething

    Basic infinitesmal doubt: Can there be a negative infinitesmal?

    What I mean is on a coordinate plane like below we take the positive x axis measure a certain distance x on it and take the infinitesmally small quantity dx next to it in the positive direction: Now can I do the opposite as in can I measure a distance negative x on the negative x axis and...
  5. Greg Bernhardt

    Announcement Small PF update this weekend

    We'll be updating PF software this coming weekend. Hoping to fix some pesky bugs! Shouldn't be down for more than 15-20min. Likely Saturday morning.
  6. paulb203

    Where Did I Go Wrong When Solving Inequalities With Negative Numbers?

    My attempt: 4>19-3x Subtract 19 from both sides: -15 > -3x Divide both sides by -3: 5 > x Switch sides (change sign): x < 5 ! But Maths Genie tells me the answer is x>5 Where have I gone wrong?
  7. pyroclasticsoul

    B How Can I Calculate Negative Multiplication Without Following Traditional Rules?

    Say I have 6 pencils. I want to times this by negative two. Now ignoring the rules that your teacher taught you work this out. 6 pencils negative 2 times. Negative one time would be 0 and another negative times would be -6 right? So 6 x - 2 = -6 according to simple logic. The calculator will say...
  8. M

    I Negative area above x-axis from integrating x^2?

    Suppose the following integration, ##\int_3^{-1} x^2 \, dx = \frac{1}{3}(-1)^3 - \frac{1}{3}(3)^3 = -\frac{28}{3}## However, if we have a look at the graph, The area between ##x = 3## and ##x = -1## is above the x-axis so should be positive. Dose anybody please know why the I am getting...
  9. doudou

    I Gravity does negative or positive work with cosmos redshift?

    Based on the fact of observed cosmological redshift, scientists have proposed different ideas to explain. One interesting question is whether gravity does negative or positive work now: According to universe expanding in Big Bang theory (Lemaitre, 1927), obviously gravity does overall negative...
  10. Bike Mi Vie

    B Negative pressure in a car to power it

    My father has an idea is powering vehicle using negative pressure. I'm trying to explain to him that I don't think that can work. He is saying that imagine you're in space and you try create negative pressure by keep on removing and the only thing that's preventing the collapse of the material...
  11. E

    Probability of Negative Value in Sz 1/2 Spin System w/ Lambda 1 & 2

    Will the probability to provide a negative value of a Sz 1/2 spin system always be 0? If lambda 1 = hbar/2 and lambda 2 = -h bar/2 ?
  12. N

    I don't understand this step in turning this negative into a positive

    So I have this question. I get all the working out, but then I feel like the answer should be; -2/(b-a). Then I thought -2/(-a+b) must just be the same thing... all good so far.. Then they somehow just to 2/(a-b) as the final answer.. I'm lost there. How does that conversion happen...
  13. curiousPep

    Engineering Can I use root locus when the input is the negative feedback?

    I have used root locus before but my confusion now is that the input is the negative feedback. Usually when I have negative feedback I consider the the error between the input (ideal) signal and the observed signal. Also, in this case what is the tranfer function since u = -k*y, and what does...
  14. C

    A Negative slope in Williamson-Hall model

    Good afternoon, I am analyzing a diffraction diagram (XRD) corresponding to a powder diffraction experiment , and I have obtained a negative slope value when plotting ##\left(\beta_{exp}-\beta_{inst}\right)\cos\theta## vs ##\sin\theta##. This implies that the strain coefficient is negative for...
  15. Y

    Coulomb's law — A negative charge balanced between 3 positive charges

    hello i would like to understand something, i found the right answer but there is still something i don't understand. here is the figure and here is my correct solution what i don't understand is why F(3,Q) is 3kQ/r^2 i mean why is the 3? i only calculat the force between q3 and Q so why...
  16. gggnano

    I Negative energy when a laser goes through lithium niobate crystal?

    A screenshot from a book which describes it: So I am trying to picture this one: 1. A laser is "pumped" through a cylinder made from lithium niobate which is placed at 90 degrees, perpendicularly...so that the laser passes through the body of the cylinder (and not through the 2 round ends)...
  17. B

    I Separation of Plasma into positive nucleus and negative electrons

    Im wondering if plasma is possible to be separated into a positive nucleus and negative electrons and contained within a magnetic bottle ? If possible, what is the most efficient method of achieving it ?
  18. anorlunda

    The Impact of Negative Leap Seconds: Risks and Challenges for IT Systems

    Conceptually, negative leap seconds are not much different than positive leap seconds. However, many or most IT systems probably have no provision for negative leap seconds and no testing for that event. Add to our list of time/date headaches; this one not Y2K related.
  19. ElectroMaster88

    B Is there some electrical charge that is neither positive nor negative?

    I do not mean neutral electrical charge, but a forth kind (if exists) I am in 9th grade, and someone asked the teacher if there is an electrical charge that is not positive, not negative and not neutral, maybe something in the middle of them. The teacher said that there is a charge like that...
  20. pandatime

    Work done in elevator problem — is it positive or negative?

    Hi! So, I've actually already solved this problem.. for the most part. I have split up the work into two sections, floor 0 to 10, and floor 10 to 15. From floor 0 to 10, I did ## F_{elevator} = w_{pass.} + w_{elev.} ## ## F = (70)(20 (num. of pass.))(9.8) + (800)(9.8) ## ## F_{elev.} = 21560N...
  21. Svelte1

    How is the slope of the shear force equal to the negative of the load?

    At any point between A and C the point load is negative (downwards), in the shear force diagram: positive is upwards, so this slope is negative. The equation says the slope should be positive. Is this something to do with shear force sign convention?
  22. D

    I Questions about Negative Pressure and Vacuum Energy

    Currently, dark energy is described as a being that exerts a negative pressure while having a positive energy density. {\rho _\Lambda } + 3{P_\Lambda } = {\rho _\Lambda } + 3( - {\rho _\Lambda }) = - 2{\rho _\Lambda } However, there seems to be a problem with the negative pressure assertion...
  23. thovarua

    MOS Capacitor under very large positive or negative bias conditions

    In MOSCAP, why does the band stop bending as soon as the Si Fermi level touches either the conduction band (inversion) or the valance band (accumulation)?
  24. Physics Slayer

    B Exploring Negative Energy at the Big Bang: A Non-Mathematical Explanation

    I was reading "Brief answers to big questions" By Hawking, the above pic is from a page of the book, it says that at the time of the big bang there was an equal amount of positive and negative energy, and that the negative energy never went anywhere, the space-time itself is a store of negative...
  25. PhysicsTest

    Negative Power Supply Clarification

    I am confused with the negative voltage supply connections in electric circuit. If i have circuit as below with -5V source it is same as below In the 2nd circuit the 5V is directly shorted with the ground, does it mean the circuit is not correct? Am i missing something? Please advise.
  26. bluesteels

    How do you know if the focal length is positive or negative?

    In this problem, it doesn't tell you where is the focal length. So how do you know if it is in front or behind the object?
  27. A

    Understanding Electric Field of Positive & Negative Plates

    I am confused with the solution. It says ##\vec E = \frac{\sigma}{\epsilon_0}##. Shouldn't E = ##2*\vec E = 2*\frac{\sigma}{\epsilon_0}##? Electric field of the positive plate and electric field of the negative plate.
  28. eognvoi

    Why is there no negative sign in the Faraday's Law stated here

    Summary:: Figure b also shows that there is no negative sign in Faraday's Law. How do I know when to include the negative sign?
  29. G

    I Interpreting Thermal Power in Cylinder with Source & Sink

    I have a cylinder that is separated with an insulator. In the internal cylinder there is a thermal source, while outside the insulator we have a thermal sink. The power of the internal cylinder is positive, while of the external one in total is negative. How I should interpet the results. Like...
  30. M

    I Force between Positive and Negative Electrical Charges

    I have in the past been criricised for inappropriate postings that I could have resolved with research so this time I have done the research first. The best solution I have found is from wiki "that causes it to experience a force when placed in an electromagnetic field." What causes the force...
  31. Mr su

    Can this comparator accept negative voltage as its negative supply?

    I check the datasheet of LM 319 high speed comparator online. I was wondering if LM 319 can accept negative supply voltage(-10V) and its possible to produce a 10V to -10V square wave which oscillates along origin rather than just 10V to 0v as shown below.
  32. karush

    MHB How Does Subtracting Negative Numbers Relate to Adding?

    Find a. Subtracting 4 is the same as adding $\boxed{(-4)}$ b. Subtracting -7 is the same as adding $\boxed{(7)}$ c. Subtracting a positive number is the same as adding a \boxed{negative} number, where that $\boxed{?}$ is opposite of the original number d. Subtracting a negative number is...
  33. rudransh verma

    Projectile negative vertical displacement

    I know how it’s done. So let’s jump on the question. The displacement that came was negative 6 cm. I want to know how this formula describes perfectly negative displacements. I don’t understand the mechanism. If I assume ##ut## to be distance traveled in absence of g then what is ##-1/2gt^2##...
  34. A

    I Can the Housie Game Incorporate Negative and Decimal Numbers?

    https://www.google.com/search?q=housie+game&sxsrf=AOaemvL_lIxvNy-2ufp2Ax01Q6aZ1Mh6qQ:1636561781166&source=hp&ei=dfOLYcL0Btn4hwPKzbfwCA&gs_ssp=eJzj4tVP1zc0TDaqNC83yTYyYPTizsgvLc5MVUhPzE0FAHSPCJk&oq=Housie+game&gs_lcp=ChFtb2JpbGUtZ3dzLXdpei1ocBABGAAyCAguEIAEELEDMgUIABCABDIFCAAQgAQyBQgAEIAEMgUIABCAB...
  35. moriah

    XLR Port Negative Pin: ZRL & Ground Explained

    Is zero reference level synonymous with the return path of a current, i.e., the negative wire? If so, where a ZRL is being used by a circuit, is the ground pin and the negative pin in a XLR port the same thing?
  36. guyvsdcsniper

    Trouble with negative sign in this Potential Difference problem

    So I know that E = -ΔV/Δs. If I wanted to solve for change in potential I could rearrange this equation and get Δ = -E*ds. With that information I believe I can solve the problem below. But in both solutions provided below, the negative sign goes away. Now I know I can pull the E out because it...
  37. P

    Engineering Finding out the input impedance in a negative feedback op-amp

    In this case, there is negative feedback. ##V_{out}## is almost equal to ##V_{in}## in this case. But I really can't understand how to even proceed to find out the input impedance in this case, from the equation I know. Can someone help me out in figuring how should I proceed?
  38. BWV

    Negative eigenvalues in covariance matrix

    Trying to run the factoran function in MATLAB on a large matrix of daily stock returns. The function requires the data to have a positive definite covariance matrix, but this data has many very small negative eigenvalues (< 10^-17), which I understand to be a floating point issue as 'real'...
  39. P

    I Is there a negative sign in front of the centrifugal potential energy?

    In orbital mechanics, the effective potential is given by ##\frac {1} {2} m r^2 w^2##, which can be expressed in terms of angular momentum ##L## which is conserved. Yet, https://web.njit.edu/~gary/321/Lecture17.html apparently shows the centrifugal potential as the negative of the above...
  40. Paige_Turner

    B Energy & Pendulums: Is Negative Energy Real?

    Does "absorbing" negative energy from gravity cancel the upward momentum of the pendulum? Or what? Where can I see energy being negative? Does it repel stuff? It sounds impossible.
  41. B

    Help With Negative Phases in a Numerical Term

    I think I've got the numerator part figured out, but I'm really stuck on what to do with those negative phases in the last term and how to get this to all come together in the end. I feel like I must have made a mistake somewhere, but can't find it. Thanks in advance for the help!
  42. Paige_Turner

    I Negative Distance Metric: Elapsed Time & Space-Time Interval

    DISTANCE METRIC, 2D: $$d = \sqrt{x^2 + y^2}$$ DISTANCE METRIC, 3D: $$d = \sqrt{x^2 + y^2 + z^2}$$ DISTANCE METRIC, 4D: $$d = \sqrt{x^2 + y^2 + z^2 - ct^2}$$ You SUBTRACT elapsed time from the spatial distance. Yes, elapsed time is called "imaginary distance," and vice versa. However...
  43. Paige_Turner

    I Negative curvature in low dimensions

    It's probably the hyperbola, but I don't see how it's curvature is negative. It looks like 2 parabolas. thanx, paige turner
  44. Haorong Wu

    I Improper density matrix with negative eigenvalues

    Hi, there. I am working with a model, in which the dimension of the Hilbert space is infinite. But Since only several states are directly coupled to the initial state and the coupling strength are weak, then I only consider a subspace spanned by these states. The calculation shows that the...
  45. D

    Engineering Over-consolidation pressure / negative skin friction of clay

    However, I can't find any proof on this ? Can someone help to explain this ?
  46. N

    MHB Modulus problem with a negative sign

    In a video, a person discussed how to solve modulus problems with a negative sign. This is the link of that video lecture. He showed two methods to solve the problem. The first method is commonly used. Later he showed another method where he used a number line and a graph. Unfortunately, I...
  47. tworitdash

    MATLAB FFT of conjugate doesn't coincide exactly at the negative frequency

    I am trying to understand why the conjugate of a signal in the time domain doesn't produce an exact flip of the frequency domain spectrum. There is always a one-pixel shift in the result. The MATLAB code is shown below. I use a flip for the conjugate spectrum to show that it doesn't match the...
  48. T

    Negative Ease in knitting (both in flat rows and in rounds)

    I am a knitter and am interested using physics to explain the negative ease we see in knitting especially in rib [ (k1, p1) rib for example). I think some could be explained by the stretch-ability of the materials, e.g. wool, acrylic, but is there a movement of the yarn in between the "live"...
  49. M

    I Checking for negative feedback in a circuit

    This is the circuit in question. During lecture, when checking whether this was negative feedback, my instructor said that if the v_out increases, then v- increases as well, which would lead to the next v_out decreasing because v_out = A(v+ - v-). I get how if v- increases the next v_out would...
  50. guyvsdcsniper

    Is Nonconservative work negative?

    I am a bit confused. My teacher solved this problem and his answer for the thermal energy produced was -147,000J. My book says it is 147000J. My teacher used the equation K2+P2=K1+P1+Wnc and my book used K1+P1=K2+P2+Wnc. Which one is it?
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