Zero Definition and 1000 Threads

  1. B

    Work done to reach the point where the gravitational potential is zero

    Hi there I have been attempting the parts to this question and I'm finding some trouble on how to answer the last part which is d)iii Here is what I have done for the rest of the parts and what I think I should start off with in part d)iii Thanks!
  2. C

    B Neutron Decay Outside of a Nucleus Near Absolute Zero

    Does neutron decay outside of the nucleus occur faster, slower, or at the same speed when the environment it is in is near absolute zero? Do any external factors affect the speed of a neutron decaying?
  3. K

    I Derivative of a function is equal to zero

    Suppose: - that I have a function ##g(t)## such that ##g(t) = \frac{dy}{dt} ##; - that ##y = y(x)## and ##x = x(t)##; - that I take the derivative of ##g## with respect to ##y##. One one hand this is ##\frac{dg}{dy} = \frac{dg}{dx}\frac{dx}{dy} = \frac{d^2 y}{dxdt}\frac{dx}{dy}##. On the other...
  4. F

    What is the Entropy at ZERO Degrees Kelvin?

    Planck states that all perfect crystalline system have the same entropy in limit T approaches zero,so we can put the entropy equal zero.Can we demonstrate that or is it only a presumption?
  5. R

    I Why a is not equal to zero in this pair of straight line equations?

    Let say we have two line ##a_1x+b_1y+c_1=0## and ##a_2x+b_2y+c_2=0##. Then pair of straight line equation is ##a_1a_2x^2+(a_1b_2+b_1a_2)xy+b_1b_2y^2+(a_1c_2+c_1a_2)x+(b_1c_2+c_1b_2)y+c_1c_2=0## i.e ##ax^2+2hxy+by^2+2gx+2fy+c=0## Now if we take ##a_1=0##, then the first line becomes...
  6. Schwann

    B Can PDF values be equal to zero at some given points?

    Suppose we have a function which looks like this: It seems like it meets criteria of probability density functions: this function is asymptotic to zero as x approaches infinity and also it is not negative. My question is: if at some points this function reaches zero (as I have shown above)...
  7. J

    Find the eigenvector with zero eigenvalues at any time t from the Hamiltonian

    I have a question relates to a 3 levels system. I have the Hamiltonian given by: H= Acos^2 bt(|1><2|+|2><1|)+Asin^2 bt(|2><3|+|3><2|) I have been asked to find that H has an eigenvector with zero eigenvalues at any time t
  8. bryanso

    Why is the Electric Field outside this wire not zero?

    Not a homework. Just self-studying electromagnetism. I am stuck at understanding the very beginning of the solution steps in this example: The E as given in the solution is the field away from a long straight line with charge Lambda. That's clearly not the current configuration. E should...
  9. M

    Field axioms - is there an axiom for multiplication with zero?

    Please refer to the screenshot below. Every step is justified with an axiom. Please see the link to the origal document at the bottom. I am trying to understand why the proof was not stopped at the encircled step. 1. Is there no axiom that says ## x \cdot 0 = 0 ## ? 2. Isn't the sixth...
  10. E

    Work done by a tangential force shouldn't be zero

    Applying the dot product to the position vector and force vectors yields the result that the force vector is always at 90 degrees to the position vector, namely that it is directed tangentially. The mark scheme gives the work done as 0, however I don't agree. I believe they got this by finding...
  11. D

    How to show that the electric field inside a spherical shell is zero?

    Hi! I need help with this problem. I tried to do it the way you can see in the picture. I then has this: ##dE_z=dE\cdot \cos\theta## thus ##dE_z=\frac{\sigma dA}{4\pi\epsilon_0}\cos\theta=\frac{\sigma 2\pi L^2\sin\theta d\theta}{4\pi\epsilon_0 L^2}\cos\theta##. Then I integrated and ended up...
  12. FQVBSina_Jesse

    Question about net work and displacement

    I know that by physics definition if displacement is zero, work is zero. However, if I push an object 5 m to the east, and then move to the other side of the object and push it 5 m back to the west. I think in this case I have always done positive work on the object and hence the total work...
  13. C

    MHB Zero divisor for polynomial rings

    Dear Everybody,I am having trouble with how to begin with this problem from Abstract Algebra by Dummit and Foote (2nd ed): Let $R$ be a commutative ring with 1. Let $p(x)=a_nx^n+a_{n-1}x^{n-1}+\cdots+a_1x+a_0$ be an element of the polynomial ring $R[x]$. Prove that $p(x)$ is a zero divisor in...
  14. peguerosdc

    How to relate the gravitational potential energy zero to the axes?

    (Throughout all my post, I will refer to “gravitational potential energy” just as “potential energy”) Hi! I have this confusion about when is potential energy positive/negative and how it is related to how we define our axes. I think it is easier to understand my confusion with the following...
  15. P

    MCNP error zero lattice element hit

    I have been encountering "zero lattice element hit" when I try to run it in MCNP5. The input file is provided below. The square lattice runs fine, but the hexagonal does not. Hope someone can help me here. Thank you.
  16. D

    The distance where the magnetic field of two wires is zero

    Homework Statement: The distance between two parallel long wires, carrying currents equal to i and 3i respectively, is d as shown in the picture. What is the distance from the wire carrying the current i at which the magnetic field is zero Homework Equations: guess biot-savarat Being two...
  17. K

    Result is zero flux for MCNP6 *F4 tally

    I am trying yo find the flux in a cell which is bounded by two concentric spheres and a cone. When I run the code I get a warning that no cross section tables are called for in this problem and a tally result of zero. The way I defined the surfaces and cells is below if anyone sees where I...
  18. M

    Zero Friction on the Moon: Driving at Constant Velocity Without Air Resistance

    Suppose we are driving on moon (I mean there is not air resistance) at a constant velocity. Suddenly the car goes on an icy land (the friction is zero). What happens? In other words, if we drive at constant velocity and there isn't air resistance, Is there any friction force between tires and...
  19. DaTario

    Zero Limit of Sum of Squares of Terms with Bounded Range

    I don't know how to show that this limit is zero. It seems that ##\sum_{i=1}^N a_{i,N} /N = 1## and the fact that ## 0 < a_{i,N} < M > 1## implies that some ##a_{i,N}## are less than one. Another conclusion I guess is correct to draw is that ##\lim_{N \to \infty} \sum_{i=1}^N a_{i,N}^2 /N < 1##.
  20. karush

    MHB 5.3 Show that a square matrix with a zero row is not invertible.

    Show that a square matrix with a zero row is not invertible. first a matrix has to be a square to be invertable if $$\det \begin{pmatrix}1&0&0\\ 0&1&0\\ 3&0&1\end{pmatrix}=1$$ then $$\begin{pmatrix} 1&0&0\\ 0&1&0\\ 3&0&1\end{pmatrix}^{-1} =\begin{pmatrix}1&0&0\\ 0&1&0\\ -3&0&1...
  21. B

    I Integration: When to multiply by one or add zero?

    I have seen several functions be integrated by multiplying by a form of one or by adding a form of zero. When is it advantageous do do one of these things? Are there any example problems (Calc I or II) in which I can try these techniques?
  22. th078

    Radio frequency shielding for Raspberry Pi Zero

    So I'm trying to put together a Pi Zero mini computer to use for security-oriented applications, for example encrypting/decrypting messages, working with encryption keys, etc. It's cheap, very small and thus easy to carry around. However, I'm not entirely comfortable with the presence of the...
  23. D

    I Division of a complex number by zero

    Hi I know that division of a real number by zero is not defined. I just came across the following in a textbook on Complex Analysis by Priestley , " we are allowed to divide a complex number by zero as long as the complex number ≠ 0 " Is this correct ? What happens if the complex number is...
  24. Benjamin_harsh

    How is the coefficient of restitution zero for this problem?

    ##coefficient\; of \;restitution = \large\frac{Relative\; speed \;after \;collision}{Relative\; speed\; before\; collision} \normalsize= 0##
  25. entropy1

    I Creation of our universe from zero energy?

    If the creation of our universe went alongside with creation of a second universe wherein each particle in our universe had a counterpart particle in it with opposite momentum, could those universes (our+second one) be created from zero energy?
  26. C

    Safe zero base reactivity level nuclear fission reactor?

    There are already 4 generations of nuclear fission reactors. (Compare https://en.wikipedia.org/wiki/Nuclear_reactor#By_generation.) However among these, there does not seem to be a (maximum) safe nuclear fission reactor design, which immediately stops the nuclear chain reaction when the reactor...
  27. N

    MHB Zero: Natural or Counting Number?

    Zero is an integer. An integer is defined as all positive and negative whole numbers and zero. Zero is also a whole number, a rational number and a real number, but it is not typically considered a natural number, nor is it an irrational number. Why is 0 not a natural or counting number?
  28. D

    Optimized "4 Zero Force Members: Check If You Have It Right

    This truss is supposed to have 4 zero force members and i have picked the following. Does it look right? Left side: Join has 2 members of which the colinear are the 2 vertical members and so the horizontal must be 0 Right side: Join has 2 members with no external load, therefore both are 0 I am...
  29. K

    Standard Gibbs free energy equal to zero?

    At equilibrium, we know that deltaG = 0. But what about deltaG_zero, i.e. the standard Gibbs free energy? When is deltaG_zero = 0? In the solution manual it says that it means that K = 1, but by calculating an equilibrium constant you are already stating that we are at equilibrium? I.e. that...
  30. B

    AQA physics paper question: Where is the potential zero near these charges?

    This question is a bit werid because would there be a resulatant electric potential equal to zero as we have a positive and negative charge in which case there's no neutral point. As E1-E2 , they have to be acting in oppostie directions , in this case would they be acting in the same direction.
  31. Y

    Magnetic force -- does it fall off to zero far away from the source?

    Let's say we have a wire and a circuit is closed the magnetic field start to spread with speed of light c. Then we would have a place " out of range " at which the magnetic field doesn't exist.What is the equation that connects magnetic force with distance with its prorogation of speed of light...
  32. TerranIV

    I Particles w/ 0 Inertial Mass Traveling Faster than Light?

    I was just curious if there were any known (theoretical) particles with zero inertial mass that don't travel at light speed. Is this even possible?
  33. C

    Diode operation from reverse bias to zero bias

    Assume we have a closed diode circuit .We connect the n type region of the diode to the positive terminal of the battery.We connect the p type region of the diode to the negative terminal of the battery.The depletion layer is increased.Now we open the circuit.Why the diode returns to its zero...
  34. H

    How is the energy of a zero resistance circuit converted to rotational energy?

    If I have a DC induction motor coil of a zero resistance so that means that to sustain a constant magnetic field I do not need any energy. So in a DC motor how is energy of zero resistance circuit converted to rotational energy of a motor?
  35. J

    Implications of zero in the denominator when solving equations

    My book states the following : ##{\frac{(y_1)-(y_2)}{(x_1)-(x_2)}}*\frac{(3+1)}{(0-0)} = -1## ...(1) ##\implies y_1 - y_2 = 0## (A) Is this a valid deduction? Context : The Problem :If ##A(0,-1)## and ##B(0,3)## are two opposite vertices of a square, then find the other two vertices...
  36. EEristavi

    Object causing another object to move with zero friction

    Homework Statement This is the problem from the book "physics for scientists and engineers..." by Serway, Jewett / Chapter 5, problem 98 Initially, the system of objects shown in Figure P5.93 - is held motionless. The pulley and all surfaces and wheels are frictionless. Let the force F be...
  37. P

    Fault in ungrounded system -> zero sequence voltage

    Hi. After some study, I came across symmetrical components. I found the attached schematic below on the internet, and will use it to explain my question. Question: Imagine that a single-line to Earth fault occur in one of the phases, i.e. resulting in an unbalanced system (we assume it was...
  38. Mbuso

    Is Zero Divided by Zero Equal to One?

    Why is the division of zero by itself not equal to one,since it is conventional that any number divided by itself is equal to one?,or maybe is zero not a number?
  39. A

    Absolute Zero v. The Speed of Light

    Hello, I have a physics question that I am hoping the forum can answer. I have lots of them actually, but I would like to start with the one question and go from there. Ideally the answer to the question should be based upon current accepted physics theory. The Question: How do objects...
  40. F

    How effective is Charles' Law in determining absolute zero?

    Homework Statement Okie so I'm working on my physics work, and I need to compare Charles' Law (for finding absolute zero) to another method used to calculate absolute zero. 3. Attempt at the Solution For this, I was thinking of looking at Carnot engine, but I absolutely do not understand and...
  41. karush

    MHB E1.4b Determinant with zero column

    $$\left[\begin{array}{rrrrr} 1 &0 &2 &1\\ 1 &1 &0 &1\\ 1 &3 &4 &1\\ -1 &-3 &-4 &-1 \end{array}\right]=\color{red}{0}$$Answer (red) via W|Aok I did not do any operations on this Since by observation the 4th column can become all zero'showever didn't see anything in the book to support...
  42. EEristavi

    Solving a System of Equations via the Matrix Method

    I have equation system: x + y + z - a*k = 0 -b*x + y + z = 0 -c*y + z = 0 -d*x + y = 0 where: a, b, c, d = const. Have to find: x, y, z, k Attempt of solution: I create Matrix A with coefficients; Matrix B - Solutions (Zeros) and Matrix X - variables. When I try to use Cramer's rule -...
  43. Kaan99

    Electrostatic self-force is zero

    Homework Statement Consider a charged body of finite size, (\rho=0 outside a bounded region V). \vec{E} is the electric field produced by the body. Suppose \vec{E} \rightarrow 0 at infinity. Show that the total self-force is zero: \int_V \rho \vec{E} dV = \vec{0}, i.e. the charged body does not...
  44. DaveC426913

    B Cause of time dilation when net gravity is zero

    I'm armchair knowledgeable about GR, but I've come up against something I can't eloquently explain (to someone who asserts otherwise and wants an unassailable answer). What property results in time dilation even when net gravity is zero?The net gravity at the centre of the Earth is zero, but...
  45. D

    If a particle was at position X for zero time, was it there?

    A moving particle has been at position X for zero time. Was it ever at position X? Can zero time be considered as never, as in "I was in Rome for zero amount of time."? It seems like it would have been at position X if time passed in pieces the size of Plank time.
  46. X

    I Zero Gravity Near a Black Hole?

    This is probably a fairly simple question, but I am struggling with it. My question is: Would you experience the effects of gravity if orbiting in a stable or circular orbit close to a black hole? This stems from my mental image of the International Space Station (ISS). There is obviously...
  47. H

    I Curvature of space in large regions: zero or not?

    I have read numerous times that the overall curvature of space in extremely large regions -1000s of megaparsecs say - is zero. I also keep reading that the expansion rate of the universe is increasing, and that the universe is resultantly positively curved. I would be interested in a...
  48. binbagsss

    Complex function open set, sequence, identically zero, proof

    Homework Statement Hi I am looking at this proof that , if on an open connected set, U,there exists a convergent sequence of on this open set, and f(z_n) is zero for any such n, for a holomorphic function, then f(z) is identically zero everywhere. ##f: u \to C##Please see attachment...
  49. Luxucs

    Faraday's Law with Zero Resistance Current Loop

    Hi there, I was recently helping a friend of mine with a fairly standard electromagnetic induction problem (a basic sketch of the set-up is attached) where we have a current loop with resistance ##R## moving through a magnetic dipole and had to roughly sketch out the current induced in the loop...
  50. R

    B Does time dilation prove the existence of an absolute zero velocity?

    You may think you've seen this before, since I've seen similar discussions in the archives of this, but I think I've distilled the thoughts down to a couple of facts that contradict the common beliefs regarding relativity. Let me preface this with a basic observation: Lorenz invariance does not...
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