Zero Definition and 1000 Threads

I was trying to emulate a packed bed reactor, and apparently the pressure midway at the packed column became zero, until my numerical method failed altogether (as the pressure variable in the Ergun is at the denominator). I'd like to be enlightened about one thing - does this phenomena (zero...

Consider a data matrix, X, with zero empirical mean. What is zero empirical mean? Could someone please give me an example of such matrix?

Homework Statement In the circuit, find the value of V3 such that the current through the 10Ω resistor is zero. Homework Equations V=IR The Attempt at a Solution I am not sure how to apply Kirchoffs loop rule to this situation. If I want the current through the resistor to be zero...

E = mc^2 results in c^2 = E / m, and division by 0 is undefined.

What is "zero action" Hello All, I have been reading this thread, trying to understand the concept of action. There is one very intriguing (to me) statement in that thread: "So your action is the difference between your capability of motion and your actual motion. The principle of least...

Homework Statement Hi everyone. I am trying to calculate $$f(k) = \int_{-\infty}^0 e^{-i k t} dt.$$ Homework Equations Of course we know that $$\int_{-\infty}^{\infty} e^{-i k t} dt = 2 \pi \delta(k)$$ and in fact (I think) I know that the answer to my question must be $$f(k) = \frac{i}{k}...

Hello, Does anyone know what "induced gravity" is and where can one read (something not too technical) about it? I am trying to understand how a system with zero Lagrangian has something to do with gravity. Could someone explain perhaps? Thanks

Hi, Since velocity is a vector quantity I assume it follows that KE must also by a vector since KE=1/2mv squared. Is it true to say a rotating object has zero total velocity since + = - and therefore the total KE is zero? Thanks

Homework Statement Proof that, If f is a function such that (1) f is differentiable at (open) the interval D, (2) D includes 0 and f(0)=0, and (3) for all x in D other than 0, f(x) and x have opposite signs Then f'(0)\leq0 Homework Equations None. The Attempt at a Solution I managed...

If equimolar amounts of iodine and propanone are reacted in acidic conditions, the [propanone] vs time graph would be expected to show an exponential decay as expected from first order kinetics. The [iodine] vs time graph vs time must therefore also be an exponential decay in order to obey the...

Given A(m,n), eps = Machine Epsilon, fNorm = FrobeniusNorm(A), p >= 1 To filter noise near zero created by floating point error: if (|Aij| < fNorm * eps *p) Aij =0 end if Seem reasonable?

Homework Statement Two charges of q1=4μC and q2=-1μC are separted by a distance of 3 m.Find and justify the zero field location. Homework Equations E=\frac{kQ}{r^{2}} The Attempt at a Solution Consider a point x to the right of charge q1 where the field is zero.The distance of x...

An object above absolute zero radiates energy. This implies that object on Earth too radiate energy(infrared?) My question is, if the Earth were not moving, we would be much slower, so would we radiate in some other wavelength of the spectrum? We are essentially traveling really fast because of...

Homework Statement Two positive charges of 16 micro coulomb and 4 micro coulomb are separated by a distance 3 m along a straight line...find the spot on the line joining the two charges where Electric field is zero? Homework Equations E = F/Q and F = Q1Q2/R^2 The Attempt at a...

the two energy level atom, whose hamiltonian takes the form \hat{H_A}=E_g|g\rangle\langle g|+E_e|e\rangle\langle e|, where E_g as well as E_e represent the eigenvalues and |g\rangle as well as |e\rangle denote the ground state and excited state. There is an interaction between the atom...

Hypothetically: A pair of electrodes with a small insulating barrier between them. Transport is via tunneling through the barrier. You apply a small bias, and measure conductance because there is tunneling current. At 0 K, can there still be tunneling? Is it possible for a tunnel junction...

Homework Statement Suppose that a commutative ring R, with a unit, has no zero divisors. Does that necessarily imply that every nonzero element of R is invertible? Homework Equations The Attempt at a Solution We have to show that there exists some b in R such that ab = e. Having...

I am trying to get a better understanding of what it means for an atom to vibrate. Let's say there is a chunk of iron in deep space that starts out with a temperature of 50 degrees celsius and is rapidly losing thermal energy. I will make the following assumptions: 1. The iron has thermal...

In the absence of external forces, the electric field inside a conductor is supposed to go to zero. This is because if any field were to exist, then the charges in the conductor would experience force and continue moving until they canceled the field. However, is it true that for any system a...

Hi guys, can you please help me to understand the following question 1.Why the Electric field in a conductor in equilibrium ZERO?

Hi I have been using a textbook which shows that ∫cos z/z^2 around the circle |z|=1 is zero by doing a Laurent expansion and finding the residue is zero. I was under the impression that only analytic functions have a integral of zero around a closed surface. ( the Cauchy-Goursat Theorem )...

I'm not entirely sure if my reasoning is correct here... "[G]ive the order of each of the zeroes of the given function. 6. ##Log(1 - z)##, ##|z| < 1##" (Complex Variables, 2nd edition by Stephen D. Fisher; pg. 133) The complex logarithm function is defined in the following manner: ##log(z) =...

I worked out and verify these two formulas: \int_0^\pi \cos(x sin(\theta)) d\theta \;=\;\ \sum_{n=0}^{\infty} \frac{(-1)^n x^{2n} \pi (1)(3)(5)...(2n-1)}{(2)(4)(6)...(2n)(2n!)}\;=\; \sum_{n=0}^{\infty} \frac{(-1)^n x^{2n} \pi}{(2^2)(4^2)(6^2)...(2n)^2} \int_0^\pi \sin(x sin(\theta)) d\theta...

So I was reading up "Zero Moment Point -Thirty Five Years of Its Life" by Vukobratic for a presentation, and is said something like this: So if I am reading this right, it's saying the point where the GRF is acting upon will shift based on the magnitude of the force created by the...

Homework Statement In the above diagram, iin(t) = -0.5u(-t) + 2u(t) A R = 2 Ω L = 1 H C = 8 mF Find the zero-input, zero-state, and complete responses of vC(t) and iL(t) for t > 0. Homework Equations σ = R/2L for series RLC circuits ωn = 1/(sqrt(LC)) for RLC circuits ωd =...

Homework Statement Integrate (1 + x2)1/2 from -∏ to ∏ Homework Equations The Attempt at a Solution I substiuted x = tan(theta) but when I went to change the limits of integration I got 0 and 0. What am I doing wrong?

Hi, I'm studying calculus of variations, this is a bit of a recap of regular calculus. You got a function, but you plug a vector that is parameterized so your function becomes parameterized, then you take the derivative in 3.5, and then they say: put the parameter to zero in 3.6, but then you...

I don't understand what it means to have measure zero. Like I understand that the indicator functions is and what it does, but I am not exactly sure what measure zero is. Okay, I mean that I understand that: ## \int_{A} 1_{A} dx = \nu(A)## and this is the "volume" of some region A in...

I am a high school physics teacher and I've been trying out an experiment for my students. I used a manometer (a plastic tube in a U-shape partially filled with water) to measure the pressure of the air in a boiling tube. I placed the boiling tube into a beaker of water and varied the...

My understanding is that the presence of energy and matter curve spacetime. Is a photon considered energy? If so, how can it curve spacetime while having zero rest mass?

Homework Statement A -1.0 nC charge and a 1.0 nC charge are separated by 10.0 cm. a) At what position(s) is the electric field due to the two charges zero? b) At what position(s) is the electric potential due to the two charges zero? c) Draw a graph showing the zero electric field and zero...

Studying computer science I noticed that such complicated software and programs are basically just ones and zeros lined up. Everything is just a yes or no. Can everything be broken down into a yes or no? By everything I mean human behavior, laws of physics etc.

Homework Statement Why is the limit of ln(x)/arctan(x) as x approaches 0 from the right, not zero? Homework Equations The Attempt at a Solution I used L'hopital's rule and got zero. But question specifically states that is not the answer.

why is the electric field zero inside the DEES of a cyclotron?

why does it work only when h tends to zero? \hat{}\[\begin{array}{l} f(x + h) = xf(x)\\ Ef(x) = xf(x)\\ E = x\\ \ln E = hD\\ \ln x = hD\\ f(x) = y\\ y\ln x = hDy\\ y\ln x = h\frac{{dy}}{{dx}}\\ \int {} \ln xdx = h\int {} dy/y\\ x\log x/e = h\ln y + \ln c\\ x\log x/e = h\ln y/C\\...

Homework Statement Prove: if a\neq0 then b/a=b*a^-1 I don't know if my proof is sufficient with this one but I cannot think of another way. Also I am only supposed to use the basic axioms (e.g. commutative, distributive, existence of reciprocal...) Homework Equations 1/a=a^-1 (I am...

Homework Statement (a) Suppose you have two arrows of equal length on a tabletop. If you can move them to point in any direction but they must remain on the tabletop, how many distinct patterns are possible such that the arrows, treated as vectors, sum to...

I have been trying to find information on the crystal structure or phase of solid elemental metals at temperatures close to absolute zero, but I can only find information on there ambient structures. Does anyone know of any sources that would have thermodynamic tables for solid metals at low...

In Peskin at page 248 he finds that if he calculates the vacuum polarization that $$\Pi(q)^{\mu \nu} \propto g^{\mu \nu}\Lambda^2$$ a result which violates the Ward identity and would cause a non-zero photon mass $$M \propto \Lambda$$. But as Peskin states, the proof of the Ward identity...

I can not get convinced why for energy level, filled with an even number of electrons, the net magnetic moment is zero! If we have a level with the quantum number l, we have two electrons with opposite spins in it. Also magnetic moment is proportional to Jtotal where J_t= J_1+J_2(1and 2 refer...

Homework Statement A surface S in three dimensional space may be specified by the equation f(x, y, z) = 0, where f(x, y, z) is a real function. Show that a unit vector nˆ normal to the surface at point (x0, y0, z0) is given by Homework Equations The Attempt at a Solution r...

Homework Statement Suppose that f' (2) = 3. Find the limit as x approaches 2 of [f(x)−f(2)]/[sqrt(x) - sqrt(2)] Answer: 6*sqrt 2 Homework Equations The Attempt at a Solution f'(x) = lim h->0 = [f(a +h) - f(a)]/h = slope [f(x)-f(2)]/ x-2 a = 2 i would think that the limit =...

there are two points A and C having a finite potential difference.they are connected by a wire of non zero resistance.a current will flow through the wire.the wire is now removed and a third point B is introduced which has an potential equal to A.a wire is taken which connects A,B,C.will a...

Homework Statement This isn't strictly homework, I'm going over my lecturer's notes before the exam and I don't understand a part of this proof for magnetic fields doing no work. This is the second proof he gave, the first being the more standard \vec{B}\cdot\textit{d}\vec{l}=0...

If a resistor shares common junctions to a conductor with no resistance in a circuit, will current flow through the resistor? Also, what is the equivalent resistance between A and B as in the figure...

Homework Statement So a 1kg mass and a 2kg mass are placed 10m away from each other, somewhere in between them the force of gravity cancles out. Where would am object with a mass of m be placed so that it is not affected by either of the 1kg and 2kg masses? Homework Equations Not...

Hello I don't know much about physics but I thought I would come here because the topic interests me and I would like more professional opinions on the matter as their seems to be a lot of disinformation out there. People claiming to have created free energy machines and the like, Which make use...

Hello, the other day i was playing pool, and i wondered about the following question: when a body is subject to air resistance, does it eventually get to zero speed? Or does it gradually slow down but never reaching 0 speed? Excuse me if this question is nonsense, but when i heard about...

Hi I have a ball, and I'm lifting this ball upward with +work, and gravity is doing -work, Net Work= zero. But how is it, that I can still move the ball. When read that explanation I think of the ball or any object not moving at all :S So how can I figure this puzzle out :O?

Please bear with me. This is my first post. I've put together quickly, with the best logic I could fathom, a solution to the infamous 0/0. Does 0/0 = 1 and 0 at the same time with respect to 0? By taking zero and dividing it by zero, you acknowledge that there is, in fact, the...