Zero Definition and 1000 Threads

  1. R

    How to determine type of Filter from pole zero plot?

    According to me Transfer function will be G(s)= (s2+2ζωn+ωn2)/((s+p1)(s+p2)) I assume from the given plot that ωn < p1 and ωn < p2 Then the bode plot will be as per me like following :From the Bode plot we can see for higher freq magnitude is amplified . So it will be High pass Filter. That's...
  2. S

    Probability of AᴧBᴧBᴧC equal zero why 1

    probability of AᴧBᴧBᴧC equal zero why!1 (B v AE)ᴧ( Ev C) So after multiplication you should have AᴧBᴧBᴧC But he didnt mention this, so it should by zero ,but why!11
  3. A

    Proving the weyl tensor is zero problem

    Homework Statement Show that all Robertson - Walker models are conformally flat. Homework Equations Robertson Walker Metric: ds^{2}=a^{2}(t)\left(\frac{dr^{2}}{1-Kr^{2}}+r^{2}(d\theta^{2}+(sin\theta)^{2}d\phi^{2} )\right)-dt^{2} Ricci Tensor: R_{\alpha\beta}=2Kg_{\alpha\beta} Ricci...
  4. L

    Prove that the magnetic field at the centre of the sphere is zero when____

    A metallic sphere of radius R and specific resistance ρ is taken and two wires( negligible resistance) connected to it at random positions (say at an angle θ apart from each other.both the wires are perpendicular to the surface of the metallic sphere. Prove that the Magnetic field B at the...
  5. dexterdev

    Why do we consider zero mean for gaussian noise in a communication channel?

    Hi all, I got an idea why noise is having a gaussian pdf but didnot understood why it should be having zero mean. Why can't noise contain a dc content. -Devanand T
  6. S

    Can absolute zero ever be measured?

    HeyI was wondering - is it physically impossible to make something absolute zero and then measure it to check if it was? I often read that we bring things down to "close to absolute zero" but it never is the full way. Is it because if human or electronic device, which ever it was that tried to...
  7. M

    Set of functions that is eventually zero

    Usually, in homework problems, I come across something like, "Let F be the set of all functions f:\mathbf{N}\rightarrow\{0,1\} that are eventually zero." But I don't really understand what is meant by that. Is it right to think about it as the set of binary numbers? If I take each f to be a...
  8. J

    Showing a polynomial has at least one zero outside the unit circle.

    The first thing that we should notice is that the leading coefficient $a_n = 1$. I was thinking about considering the factored form of p. I googled, and there is an algorithm called the "Schur-Cohn Algorithm" that is suppose to answer exactly this, but I can't find any information on it or...
  9. J

    Time Dilation at Rest: Theoretical Perspectives

    I'm wondering if there are any theories of how time would be experienced by a fixed point in the universe. I realize the relative nature of the time dilation formula, but I find myself wondering if it would be any different if there was no movement at all. I mean, after all - we're all...
  10. ShayanJ

    Gauss's law and volumes with zero «net» charge

    The integral form of gauss's law is used to determine the electric field of charge distributions which possesses a certain amount of symmetry. Now imagine using it in situations where the gaussian surface includes equal amounts of positive and negative charge. For example,imagine a point...
  11. mrspeedybob

    Do Zero Magnitude Vectors Have Direction?

    I read a post in an unrelated thread to the effect that some vectors do not have a direction. I assume the poster was referring to vectors with zero magnitude. At first this makes sense but the more I thought about it the more it seems to me that zero magnitude vectors do still have direction...
  12. T

    Instantaneous Center of Zero Velocity

    Homework Statement Why is the angular velocity of link BD the same as the angular velocity of ICD? Shouldn't it be ωICD=vD/rD/IC?
  13. V

    What Defines the Zero Vector in Modified Vector Space Operations?

    Homework Statement If we give X = R2 the non-standard operations (x, y,) ⊕ (x' , y') = (x + x' - 1, y + y' +2) (vector addition) and k~(x, y) = (kx - k + 1, ky + 2k -2) (multiplication by scalars) then X is a real vector space. - What is the zero vector of X? - If v = (x, y) is in X then...
  14. A

    If both inputs in SR latch are zero

    If both the inputs in SR latch are zero and there was no previous output then what would be the output? If both the NOR gates are different then depending which one is faster the output will be accordingly, but what if both are identical?
  15. P

    Neutron capture cross section of tritium is zero

    I wish to verify a couple of assertions. From the NNDC and other references, it appears that the neutron capture cross section of 3H (Tritium) is zero to a first approximation. This holds true for all neutron energies, including cold neutrons. These statements are equivalent to asserting that 4H...
  16. 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...
  17. P

    Simple Proof That Division By Zero Is Impossible

    x / y = z, so z * y = x 1 / 0 = x, so x * 0 = 1 But 0 does not equal 1, so x / 0 is unsolvable. Oh, and I'm new to forums so if this shouldn't be here you can delete it.
  18. P

    Does zero vector only exist in dim 0?

    Hi, just curious, is it false to say the vector 0 exists in R^n, n>0 and a natural number? i.e. does x = [0, 0, 0, 0] exist in R^4, or simply the zero space? My guess is that the first statement is not false given that the zero space is a subspace of R^n, n>0. Am I right or wrong? Thanks
  19. wolram

    A Resolution of the Cosmological Constant Problem: Jan M Greben

    arXiv:1209.4734 [pdf, ps, other] A resolution of the cosmological constant problem Jan M. Greben Subjects: General Physics (physics.gen-ph) The standard calculation of vacuum energy or zero point energy is in strong disagreement with observation. We suggest that this discrepancy is caused by...
  20. P

    Why is zero considered an important number?

    My question may come as a surprise to many people but I have not understood the importance of zero and its significance. How can nothing be something? Why do we have zero as a number? If it's used for measuring then we can very well do without zero, for example if there is a fellow counting...
  21. F

    Linear systems: zero, one, infinite solutions

    Hello forum, why does a system of linear equations really have no solution or one unique solution, or infinite solutions? What forbids a system to a finite number of solutions? thanks fisico30
  22. D

    How to find net electric force of zero

    I was wondering if someone could help me with this question: A charge 3q is at the origin, and a charge -2q is on the positive x-axis at x = a. Where would you place a third charge so it would experience no net electric force? I currently set up two equations: 1. 3q*q/b^2 where b is...
  23. Artlav

    Zero voltage, non-zero current?

    Reading about solar panels i came across a peculiar description - "When the panel is short circuited, there is current but no voltage, so no power is being generated." How does that work? What does the current represent in that case, and what moves the needle of an ammeter? Another...
  24. 5

    10-year zero coupon rate, how to calculate x?

    Hi guys, I'm trying to sort out the following formula, but just can't find out how to solve for 'x'. Could you guys please help me out?? http://imageshack.us/a/img198/4850/screenshot20120917at725.png Uploaded with ImageShack.us And I have another one, is there a quick way to solve...
  25. bcrowell

    Experimental tests of zero divergence for stress-energy?

    We expect the stress-energy tensor to have zero divergence, because this is required for local conservation of energy-momentum, which has been verified to high precision in laboratory and solar system experiments. The standard review article is Will, "The Confrontation between General Relativity...
  26. S

    Helicity of the positron in zero mass limit

    Hi... I read somewhere that positron, in the massless, limit will have the same helicity as the antineutrino. This must be because they are in the same SU(2) doublet. So helicity operator must commute with the SU(2) generators. Please confirm.
  27. B

    What is zero time between events?

    if an event happens at the exact moment of another for a single observer, what does instantaneous mean? This stems from a question i posed about the speed at which two entangled particles collapse into one definite state when one is measured. It got m thinking what does zero time and...
  28. L

    Why does Einstein's 1905 SR paper contain Zero citations?

    Einstein's "Zur Elektrodynamik bewegter Körper" ("On the Electrodynamics of Moving Bodies") was published September 26. It reconciles Maxwell's equations for electricity and magnetism with the laws of mechanics by introducing major changes to mechanics close to the speed of light. This later...
  29. S

    Heat capacity of gas at zero K

    Hello All, I have been trying to find an established expression cp = cp(T) for a gas asymptotically close to zero K, as well as showing how does the function grow/behave in the low-temperature regions. This can be an idealized mono/diatomic gas Do you know a reference I can read about...
  30. S

    Exploring Matter at Zero Kelvin: Can it Exist as a Gas?

    Hello All, Can matter exist in a gaseous form at zero K? I am asking because common gasses (e.g. air) would liquify at cryogenic temperatures... Many thanks
  31. B

    Point charge configuration with zero potential energy

    is it possible to construct a system with only finite number of point charges of arbitrary magnitude at finite distance from each other such that the total potential energy is zero everywhere? i doubt earnshaw's theorem would prohibit this construction, hence is it possible? thanks
  32. V

    Zero resistivity in superconducting state

    Hi everyone, - Could you explain for me the meaning of "net" in the phrase "small net attraction between electrons" in superconductivity, (or synonym of it)? - We usually say that BSC theory explains the superconductivity of conventional superconductors, one feature of superconductivity is...
  33. S

    Division By Zero: Why Do People Call it Infinity?

    In most cases division be zero ends up with not defined , but why do people sometimes call it infinity ?
  34. C

    Justin T. Moore: Why Every Size \aleph_1 Has Measure Zero

    I have attached part of 2 pages from Justin T. Moores dissertation. I am wondering why he says every set of size \aleph_1 has measure zero. He is probably using some axioms that i am not familiar with. And I am not sure what the k_2 is. He says this towards the bottom of the...
  35. dexterdev

    What is the difference between zero scalar and zero vector?

    Can anyone clarify the concepts of zero vector and zero scalar? -Devanand T
  36. M

    How can hydrostatic pressure be zero?

    I was reading a paper and I saw a statement that says zero hydrostatic pressure. I was wondering what it means..
  37. A

    Designing a Lock-in amplifier from zero

    Hello everyone I have completed my freshman year in EE. For the summer, my professor has asked me to design a lock-in amplifier. First he has asked me to read about AD630. Now after reading the datasheet at (http://www.analog.com/static/imported-files/data_sheets/AD630.pdf), I was a bit...
  38. S

    Where can a third charge +Q be placed so that it experiences a zero force?

    I'm having a hard time trying to picture the problem: A charge of +2q is placed at the origin and a second charge of -q is placed at x= 3.0cm. Where can a third charge +Q be placed so that it experiences a zero force? Here is how I picture the problem:
  39. T

    Berman's zero energy condition for universe

    I've been looking over the quantum gravity papers that were posted on another thread, and I've got a question about Berman's calculations I'm not seeing a cosmological constant in that paper, and the identities look to me as if they won't work if you add "dark energy". Is that the case?
  40. X

    Calculating how long it takes for a comet to reach a sun of radius zero

    Homework Statement Consider the extreme case that the comet is released from rest at a distance R_max from the sun. In this case L is actually zero. Use the technique described in connection with 4.58 to find how long the comet takes to reach the sun. The radius of the sun for now is zero...
  41. F

    Does Resistance Truly Reach Zero at Absolute Zero?

    I was wondering, since resistance decreases along with temperature for most metallic conductors (usually power function), in theory, if this conductor were to be at zero kelvin, would the resistance of this material also be precisely zero, or would it just be some extremely small value? If it...
  42. marellasunny

    The Degree of the Zero Polynomial: Why is it Defined as -∞?

    I understand that mathematicians have had to define the number '0' also as a polynomial because it acts as the additive identity for the additive group of poly's.What I do not understand is why they define the degree of the zero polynomial as [ tex ]-\infty[ /tex ]. An explanation on planetMath...
  43. Femme_physics

    Zero Point Switching with transformer

    So with my final test tomorrow I thought to sneak in another question... Homework Statement The following circuit applies switch at the load RL via Zero Point Switching. The ratio of the coil windings at the transformer is N1:N2 = 4:1. The introductory voltage is a sinusoidal type and its RMS...
  44. C

    Free electrons at zero kelvin?

    At zero kelvin,are there free electrons? At zero kelvin,the free electrons should have ZERO energy.But they are able to move under the influence of a electric field? But when they are attracted towards the positive potential shouldn't they gain K.E? So they are moving at zero kelvin?
  45. M

    Zero point energy and IR spectroscopy

    I made some frequency calculations in Gaussian (using various method/basis set combos) and I have to find which method/basis set combo is the most accurate by comparing the results to literature values. I got the calculated wavenumbers along with their intensities but my professor tells me I...
  46. G

    Proving Vector Space of R^2: Solving Question and Finding Zero Vector

    Hi everyone, I am having difficulty solving the following question: Prove that the set V=R^2 with addition defined by (x,y)+(x'+y')=(x+x'+1, y+y') and scaler multiplication by k(x,y)=(kx+k-1, ky) is a vector space, find-(x+y) and the zero vector in this vector space. the following was...
  47. M

    Recursive sequence - show it does not converge to zero

    Hi guys, I'm new here at this forum, but I don't understand this problem. Let a1 be a positive real number. Define a sequence an recursively by a(n+1) = (an)^2 - 1. Show that an does not converge to zero. (Is there a1 such that the sequence an converges to some non-zero value?) I'm...
  48. K

    Work Done on Object When Net Force is Zero

    Suppose I have an object moving in a free space at initial velocity of v (no friction). Then two forces of equal magnitude but opposite directions are applied on the moving object of which one of them is in the same direction as the moving object. Is there work done by that force?
  49. S

    How to proof that the electric fielf inside a conducting shell is zero

    how to proof that the electric fielf inside a conducting shell is zero ? i don't want to solve it using gauss law and not through practically taking example but i wanted to solve it through vector by finding the resultant zero at any point? please explain?
  50. Philosophaie

    Is A Cross B Equal to Zero a Test for Orthogonal Cases?

    A cross B equals zero is a test for orthogonal cases. If AxB=0 then A is perpendicular to B.
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