Zero Definition and 1000 Threads

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...

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...

I am not sure if I am crazy, I am not a mathematician or physicist by training, but I recall doing some work where if I was interested in the limit of a function in "r space" as r-> Infinity I could just use the value of the function in "k-space" at 0 to get the value I was interested in. Is...

Mutiplication of a scalar by a 0 gives 0(scalar) And also one proves in linear vector spaces that a vector(|>) combined with 0 by multiplicative law gives |0> . Similarly can one prove that multiplication of a tensor of say rank 2,by 0 will produce a null rank 2 tensor.

Homework Statement A -14.3 nC point charge and a +24.9 nC point charge are 17.4 cm apart on the x-axis. What is the magnitude of the electric field at the two points on the x-axis where the electric potential is zero? Homework Equations V = kq/r E = kq/r^2 The Attempt at a...

I didn’t believe it when I first heard it. I don't know how to reconcile this fact with what I understand about the known laws of physics. It appears to be one of the grandest mysteries I can think of. I understand that most of the universe is empty space but zero volume is different. Anyways...

can a particle hold it's information at absolute zero?

Use the intermediate value theorem to show that f(x) has a zero in the given interval. Please show all of your work. f(x)=-3x³+6x²-4x+12;[2.2,2.3] have to use the Bolzano's Theorem(special case of the intermediate value theorm can someone please help me out with this problem?

How can light have momentum if it has zero mass? The relativistic expression for the momentum of a massive particle is p=mγv. It's possible to get confused if one tries to apply this to a particle with zero mass, since it seems as though the result would have to be zero, and yet we know based...

Is there such a thing as a Lunar solstice? When the Equator of the Moon crosses the plane of the tilt equals zero or the plane of the earth. This should occur when the True Anomaly of the Moon is at approximately 90 Degrees or 270 Degrees depending upon the Moon's Eccentricity. The...

I would like to have a function f such that f(0) = 0 and f(x) = 1 for any x>0. I can compute f in the following way: f(x) = (2*x+1)/2 - (2*x-1)/2 . Here the division is integer division. But if x=0, here we divide (2*0-1)/2 or -1/2, which is a problem. Because we do not have any number -1...

I am learning uniform circular motion and the question says: A child on a sled comes flying over the crest of a small hill. His sled does not leave the ground but he feels the normal force between his chest and the sled decrease as he goes over the hill. Explain. Now, I know that normal force...

Given a stationary state H \psi = E \psi \Rightarrow \left(-\frac{\hbar^2}{2m}\frac{\partial^2}{\partial x^2} + V(x)\right)\psi = E\psi Firstly is it true that \left<p\right> = \frac{\hbar}{i}\int\psi^* \frac{\partial \psi}{\partial x} dx= 0 ?? If it is, how do we prove it?

Homework Statement If an even degree polynomial of order 2n intersects the x-axis twice, how do I show that the (2n-1) th derivative has a zero in that interval? Homework Equations example: let g(x)=x^3(1-x). Show without computation that g'''(c) =0 for some c in (0, 1). The...

Esteemed Analysts: I am trying to rigorize the result that if f is 1-1 in a region R, then f'(z) is not zero in R. This is what I have: Assume, by contradiction, that f'(zo)=0 for zo in R. Then f can be expressed locally as : f(z)=z^k.g(z) for g(z) analytic and...

Homework Statement Calculate the center of gravity of this object: http://img638.imageshack.us/img638/8412/inddddd.jpg The Attempt at a Solution The bottom line turns out zero, so I get something over zero therefor error! http://img101.imageshack.us/img101/6995/theretherere.jpg

I was reading about the experiment of constant volume gas thermometer today. When we extrapolate the presuure -temperature lines, the lines would meet at point -273.15 degree celsius, which is zero presure. I was wondering whether it is a matter of coincidence or some science behind it. The...

Hello Forum, the formula for skin depth is both inversely proportional to conductivity and frequency omega. There seem to be 3 cases when the skin depth of a metal is exactly (or tends to) zero: 1) if an EM wave of frequency f (any frequency) is incident on a perfect metal wall (infinite...

Homework Statement Vector 'A' is along postive z-axis and its vector product with another vector 'B' is zero , then vector 'B' could be .. a) i + j b) 4i c) i + k d) -7k . Homework Equations The Attempt at a Solution

I'm not a scientist, but I really enjoy reading the perspectives on these boards. I have some questions I hoping to hear a lot of perspectives on. I know absolute zero has never been reached, but in what ways are we attempting to find absolute zero currently? If, hypothetically, we were...

Hi I am after any information regarding zero pole plots, specifically with reference to filters. I understand the process of getting the transfer function and plotting it. But once its been plotted how do you go about translating that into a frequency response. I am also wondering about...