Zero Definition and 1000 Threads

A harmonic function in a region is zero on an open portion of the boundary, and its normal derivative is also zero on the same part, and it is continuously differentiable on the boundary. I have to show that the function is zero everywhere, but I have no idea how. I have tried this for hours...

My memory on this is a bit foggy, but a couple of years ago one my math professors had a digression about a system of voting where no one would be able to know what anyone else voted. It involved the graph of a polynomial, and the kicker was that this system couldn't be implemented in society...

Homework Statement While studying a book "analysis on manifolds" by munkres, I see a definition of measure zero. That is, Let A be a subset of R^{n}. We say A has measure zero in R^{n} if for every ε>0, there is a covering Q_{1},Q_{2},... of A by countably many rectangles...

as we know that light consist packets of energy called photons And mass of a body when moving with the speed of light increases so, the mass of photon increases when it moves with light and when mass increases its energy is also increasing it means that when light travels it never stops and...

Individual Photons Are Zero Mass Particles. Is Zero Mass Defined By This? Is zero mass as we know declaired because photons are theorisized to be true "weightless" and massless, or could it be a case that we do not have sensitive enough instrements and limited in our detection? Or on the other...

does particles stop radiating or do particles have kinetic energy at absolute zero?

A = [0 0] [1 -3] (2 x 2 matrix, bad formatting) I need to find the eigenvector for lambda1 and lambda2. I figured out lambda1 = 0 and lambda2 = -3. For lambda1 the eigenvector works fine, but for lambda2 I get it as v = (0,0), which is not possible. Any ideas?

I made an animation to explain how cats can initiate rotation and turn around during free fall, without violating the conservation of angular momentum: https://www.youtube.com/watch?v=yGusK69XVlk Some footage of real cats: https://www.youtube.com/watch?v=Ua4Gh_4XdwQ...

The kinds of experiments involving animals in space have only answered simple questions of survivability in captivity where human assistance is at hand. The big problems of space colonization have yet to be answered. I thought up this question when someone on this forum posted a response to my...

Let δ(x)=∞ at x = 0, and zero elsewhere. Then δ(x)(1-exp(x)) = ? It seems the above expression is zero. But isn't it zero times infinity at x = 0?

Homework Statement Given F1= 36N[25degrees N of E] and F2= 42N [15 degrees E of S], determine the force F3 that must be added to the sum of F1+F2 to produce a net force of zero. Homework Equations Sine law, a/sina= b/sinb Cosine law: c^2= a^2 + b^2- 2(a)(b) Cos(theta) The Attempt...

Homework Statement Hopefully an easy question. Let M be an n-dimensional smooth manifold and f: M \to \mathbb R a smooth function. Assume the covector field df is given in some coordinate basis as df = \sum_{i=1}^n a_i dx^i . Find all points p \in M such that the df_p = 0 The Attempt at...

how potential energy of electric dipole perpendicular to electric field is zero in this situation the torque is maximum so how P.E. can be zero please help

With the last year or so I came across a great discussion in these forums about the different types of infinity. It had never occurred to me there would necessarily be different types with different "values". How about zero? Are there different mathematical concepts regarding it or are all...

Hello! If you do a plot in Mathematica, for example Plot[Sin[x], {x, -, 2 Pi}] it won't put zero near origin of coordinates. So how can do it ? I tryed actually AxesOrigin or smth like that, but it didn't help me. Thanks!

Not a homework question - Just wondering. What is the real meaning of non-zero velocity compared to non-zero acceleration like i don't really understand the difference. Anyone care to explain?

why do we call a zero watts bulb as it so?? a zero watts bulb is common in houses,commonly called as 'night lamp'.., if v say it as zero watts lamp., then is it conducts zero current or zero voltage? what is the power consumption by modern led lamps and by other fluorescent lamps??

Homework Statement Prove that \Sigma^{n}_{k=1} wk = 0 and there has to be at least two phasors/exponentials Homework Equations complex analysis The Attempt at a Solution I tried writing out the sigma on the first line. Then I tried writing the same thing with n+1 on the...

Is it true in general that if f is Lebesgue integrable in a measure space (X,\mathcal M,\mu) with \mu a positive measure, \mu(X) = 1, and E \in \mathcal M satisfies \mu(E) = 0, then \int_E f d\mu = 0 This is one of those things I "knew" to be true yesterday, and the day before, and the...

Homework Statement A boy supports a book on his hand while standing still. Then, he walks with the book laying motionless on his hand. Is there work exerted by the boy on the book? 2. The attempt at a solution My professor said that there is zero work done on the book because of the...

How can you let Initial position and initioal velocity be equal to zero? I understand that it will be zero at time = 0, but as time goes on from 1, 2 , 3 , 4 won't it change? I underlined that it in read in the picture?

Homework Statement A hot-air balloon rises from the ground with a velocity of (3.00m/s)y. A champagne bottle is opened to celebrate takeoff, expelling the cork horizontally with a velocity of (4.00m/s)x relative to the balloon. When opened, the bottle is 5.00m above the ground. What is...

Homework Statement If m*(E)=0, then m*(E^2)=0. The Attempt at a Solution I have observations which may or may not make sense. Obviously we have that {Ik} is a cover of E. So we want {I2k} to be a cover E2. I have a chain of inequalities which may/may not make sense. 0 = m*(E)...

Hi, I understand for metals the conduction band is usually partially filled. However, at absolute zero, is the conduction band empty (for metals)? I'm asking this because as far as I know, the definition of valence band is "the highest occupied band at absolute zero" However, I have...

Homework Statement Show that the vector v = \frac{\hat{r}}{r2} (not sure why formatting isn't working?) v = (r-hat) over (r squared) has zero divergence (it is solenoidal) and zero curl (it is irrotational) for r not equal to 0 Homework Equations div(V) = (d/dx)V_x + (d/dy)V_y +...

Unphysical Division By Zero for Trivial Case of Zero Field Location Homework Statement Q1 and Q2 are two positive charges a distance s apart. Find the distance x from Q1 where the field is zero. Homework Equations E=\frac{kq}{r^2} The Attempt at a Solution Let's put Q1 at the...

Is it weird that at absolute zero in a metal, electrons at the fermi level still move around at the fermi velocity. Is the notion that everything stops at absolute zero incorrect? Thank you

I am aware that Bessel functions of any order p are zero in the limit where x approaches infinity. From the formula of Bessel functions, I can't see why this is. The formula is: J_p\left(x\right)=\sum_{n=0}^{\infty}...

How is tangential accleration zero in uniform circular motion?? Homework Statement the magnitude of tangential velocity is same but the directions are different..so how can the tangential acceleration be zero?? Homework Equations The Attempt at a Solution

As a semi conductor approaches absolute zero there should be zero conductivity, the thermal energy that electrons acquire is or can be responsible for promoting electrons from the valence band to the conduction band to provide current flow in a semi conductor ( for t>0). My question is...

Homework Statement Two particles with positive charges q_1 and q_2 are separated by a distance s. Along the line connecting the two charges, at what distance from the charge q_1 is the total electric field from the two charges zero? (Express your answer in terms of some or all of the...

Is Zero a positive or negative whole number ? Is it even a whole number ?

Please teach me this: Why some books only consider zero mass limit when they consider the renormalization group.I have been wondered this because the mass parameter multiplying with relevant operator,it become growth when momentum grows. Thank you very much in advance.

i read that if u r in "spaceship" that's for example has circular orbit around Earth - than u r in a zero gravity state. but from Newton law u get this equations : mMG/R^2-N=mV^2/R so from this i get that N equal MG/R^2-V^2/R and why would MG/R^2-V^2/R be zero ? no metter what?

anybody knows DVR(Discrete variable representation) method? how do you use DVR to calculate the zero point energy?

Homework Statement Is it possible to have zero average speed but nonzero average velocity? Homework Equations The Attempt at a Solution This is probably completely wrong, but I'll put it up anyway: If one's frame of reference is also the center of an arbitrary circle, then an...

In QFT after the Hamiltonian is normal ordered I guess when acting on the lowest energy state it annihilates it. So doesn't that mean the energy is zero now instead of 1/2?

why shouldn't the meissner effect occur in a non conventional zero material?

Homework Statement Point charges +q and -q are placed at +50 cm and -50 cm on the x-axis, respectively. Is the electric field at the origin (halfway between the charges) zero or nonzero? If nonzero, which direction does it point? Homework Equations The Attempt at a Solution If...

I've TeX'ed this up directly from my class notes. The argument purports to show that a function g\in L^2[0,1] is zero almost everywhere (a.e.). I dont' see how...can someone help me fill in the missing steps? I'm with him pretty much until the last line... Let x_n \to 0, x'_n \to g, both in the...

Homework Statement Point charges +q and -q are placed at +50 cm and -50 cm on the x-axis, respectively. Is the electric field at the origin (halfway between the charges) zero or nonzero? If nonzero, which direction does it point? Homework Equations The Attempt at a Solution Well...

Suppose we have a function u=f(x,y,z) If \frac{\partial u}{\partial x} = 0 then u is independent of x and is u=f(y,z) only. Correct?

say, a = [1,2,3; 0,0,0; 0,4,5]; how can I remove the rows of a that contain only zeros? I found a link which works, but I don't know why: http://www.mathworks.in/matlabcentral/newsreader/view_thread/281578 Suggesting: a(all(a==0,2),:)=[] 1. what does the "=[]" syntax do 2. can...

What happens at -273 oC? (everything under 1atm) I know about the cooling curve but just wondering what would happen to substances at absolute zero- does the temperature keep reducing/get harder? Also, how do gases stay in gaseous form in outer space? Many thanks in advance! :)

Frobenius Method Exceptional case r1=r2 For the Frobenius Method for the exceptional case r1=r2... is the equation for the second solution y_{2}= y_{1} ln (x) + x^{r_{1}+1}\sum_{n=0}^{\infty}b_{n}x^{n} or y_{2}= y_{1} ln (x) + x^{r_{1}}\sum_{n=1}^{\infty}b_{n}x^{n} In a way both...

Hello. I have a very quick op amp question. I'm trying to understand an omp amp. My question is will vout of an op amp go to zero if the inverting input is greater than the non inverting input ( even if there's a negative/positive feedback)?

I know that water forms different kinds of crystals in different kind of temperatures but is there any temperature where water is solid but does not form crystals for example just above absolute zero degrees, what kind of crystals does it form?

Homework Statement Show that in this set-up, the potential at a generic point (-x, 0, 0) (for x positive) is zero: two point charges placed at (-a, 0, +a) and (-a, 0, -a) the mirror charges are (a, 0, +a) and (a, 0, -a) The Attempt at a Solution V=(q/(4 pi epsilon0)) ((1/(sqrt((x^2...

Ok someone tell me the official explanation of why alpha cannot be zero in hypothesis testing.

In Weinberg QFT vol 1, page 69, when deriving the little group structure for the case of zero mass can anyone explain the following: The transformation W by definition leaves k^{\mu}=(0,0,1,1) invariant, i.e. W^{\mu}_{\nu}k^{\nu} = k^{\mu} . Why can you immediately deduce from this that for...