Strange Definition and 549 Threads

If you check out https://www.physicsforums.com/showthread.php?t=282332", you'll see some LaTeX strangeness. Specifically, not all the images appear, and the ones that do appear seem not to match the LaTeX source. It's almost as if the images are offset: i.e. the n-th bit of source ends up...

Hello, I am interested in tinkering with electronics and learning how to design / execute projects, and I thought I'd start out with a kit. I was wondering what kits, if any are recommended / of good use, and if you don't use them, where you recommend I find spare electronics parts for my...

Salutations, The answer obtained below doesn't match any of the options given in the enunciation. Thank you in advance. Homework Statement A sample of dolomitic limestone, containing 60% of calcium carbonate and 21% of magnesium carbonate, goes through decomposition when heated, according to...

We know x^2 = x*x*x*x... x times If we differentiate both sides with respect to x, we have 2x=1+1+1+... x times i.e. 2x=x i.e 1=2 How is it possible or am i making a mistake? Please helpp!

Strange Laplacian of 1/|x-x’| !? Please read the file first (http://www.pa.msu.edu/courses/2007fall/PHY481/lectures/lecture08.pdf" ) .. and look into page 8 there is a sentence like this "Evaluate right side with sphere, radius R around origin" Now there comes up against a question ...

Hi everyone! My first post, so bear with me. I have a query that I didn't quite know who to ask about, and came across this site, so I hope this is the right place to put it. My cat's bowl was left (empty) on the verandah and got caught in the rain yesterday afternoon. Overnight...

Homework Statement Suppose that the 2x2 matrix A has eigenvalues lambda = 1,3 with corresponding eigenvectors [2,-1]^T and [3,2]^T. Find a formula for the entries of A^n for any integer n. And then, find A and A^-1 from your formula. Homework Equations Ax = lambda X (P^-1)AP = D A =...

Hi to all, I have a question. Can anyone tell me how this strange sand bag http://www.stormtec.net/ work? I don't this that's magic lol

DZero experiment at the U.S. Department of Energy's Fermi National Accelerator Laboratory have discovered a new particle made of three quarks, the Omega-sub-b (Ωb). Read more about the 'Doubly Strange' Particle.

I'm sorry if this is the wrong forum but in a problem I was given wavelength with the unit as an A with a circle above it, can anyone tell me what this means and how I can get it into more familiar terms (meters, for example)?

I realized something weird. That, suppose you take the rationals in [0,1], call this set Q. Q's a Borel set, so if \mu is Lebesgue measure, \mu(Q)=inf(\mu(V), V open, Q \subset V). Q can be covered by open sets of total measure \le 1 by counting the rationals; cover the first rational by an...

Could someone please tell me if this is true or not, and if it is true, help me to understand why? This is a famous demonstration of how hard we find it to work out probabilities. When it was published in Parade magazine in 1990, the magazine got around 10,000 letters in response92% of which...

Strange thing about the Olympics- Track Runners' "USA" Why do the track runners from the United States have their "USA" in magic marker, while the others are clearly printed? http://www.flickr.com/photos/29601881@N05/2787191037/

let be the identity (2 \pi ) i^{m-1}D^{m} \delta (u) = \int_{-\infty}^{\infty} dx e^{iux}x^{m-1} ` then making the replacement u=e^D D derivative with respect to 'x' then (2 \pi ) i^{m-1}D^{m} \delta (e^{D})f(0) = \int_{-\infty}^{\infty} dx...

Driving home this morning the rain was teeming down, we often get teeming rain in periods of drought, but just at the edge of my property it stopped, i could literally take one step from rain to dry, i know a storm has to have boundaries but to be so abrupt was strange.

Here's a problem Let k: R\{-1} → R be given by k(x) = \frac{2x-1}{x+1} Prove that k is neither even nor odd. That is strange! But to prove it we go back to the definition; A function, f: (-a,a) \rightarrow R is said to be even if for all x \in (-a,a) => f(x) = f(-x) And it is odd if...

I was watching DonnyLee's videos on youtube and I noticed something strange. I think he picked u=x and du=dx, and if I'm right (?) he picked v= \int x dy/dx but does that even equal to y? But that can't be right because the right side kept the original expression. Some help might clear up the...

I forgot about this for about 2 years. It all started, in the summer a few years back. My hand started swelling in a little patch on the top of my hand. I scratched it and it proceeded to swell up into a painful lump. (Is it always the case that swelling on the hands becomes painful due to the...

About a year and a half ago, I had an MRI. During the scan something very strange kept happening. The procedure was actually a series of many scans - it took over an hour to get them all done. Before each one, the tech would go through a procedure he called tuning. The machine would hum...

Check this formula: \sin(x) \] \cos(x) The \] there (click formula for source) seems to cause some strange indenting for sin(x). Is this a bug in the Latex formula generator?

I tried to make a double-slit experiment, but I got some difficult-to-explain results. I cut a piece of opaque plastic in two and then stuck it back together with a human hair (mine) stretched in between, thus forming a double slit. I then mounted the "double slit" 1m from a sheet of white...

surfing the web and arxiv i found the strange formula lnA= \frac{d^{n}}{ds^{n}} \frac{s^{n-1}}{n! A^{s}} my question is .. where does this formula come from ?? here 'n' is supposed to be a finite parameter we must define to avoid the divergences, is it valid for non-renormalizable or...

Take a look at this following paragraph that i wrote in another thread "think of two rockets moving at each other under inertia at a course so that they pass very close. Observer A will look at both clocks when the rockets pass. he will see his own as being T and he will see observer B,s...

in the .pdf article http://repository.dl.itc.u-tokyo.ac.jp/dspace/bitstream/2261/6027/1/jfs080104.pdf i have found the strange representation \delta (x) = -\frac{1}{2i \pi} [z^{-1}]_{z=x} and a similar formula for Heaviside function replacing 1/z by log(-z) , what is the meaning ...

\sum\ (m^2+n^2) = 2\pi\int^{\infty}_{1} (\frac{1}{r^2} r dr) The sum goes over \mathbb{N}\times \mathbb{N}

http://www.cbsnews.com/stories/2008/05/29/ap/strange/main4136265.shtml?source=search_story

Recall that for a function f:A\subset \mathbb{R}^n\rightarrow \mathbb{R}^m, the derivative of f at x is defined as the linear map L:R^n-->R^m such that ||f(x+h)-f(x)-L(h)||=o(||h||) if such a linear map exists. We can show that for certain geometries of the set A, when the derivative exists...

Hi! I have big problem with solve this equation: m\frac{d^{2}x}{dt^{2}}+ksinx=0 I can't go ahead, because I don't know how solve this \frac{dx}{\sqrt{cosx}}=\sqrt{\frac{2k}{m}}dt Phizyk

Homework Statement An apple weighs 1.11 N. When you hang it from the end of a long spring of force constant 1.53 N/m and negligible mass, it bounces up and down in SHM. If you stop the bouncing and let the apple swing from side to side through a small angle, the frequency of this simple...

First of all, I'm an electrical engineer, I had to take a class on modern physics, so answers don't need to be "dumbed down" so let me START with the question: Can anyone see a flaw in my logic/interpretation of what's happening? My goal is to gain a more accurate conceptual (not mathematical)...

I was told to sketch this graph: y=\frac{x-1}{x^2-100} when x=0,y=.01 y=\frac{\frac{1}{x}-\frac{1}{x^2}}{1-\frac{100}{x^2}} as x \rightarrow \infty;y \rightarrow 0 \Rightarrow y=0 (i.e. x-axis is a horizontal asymptote to the curve) BUT when y=0; x-1=0 so that x=1. So a point...

I'm not sure where to put this but I though DEQ would be a good start. I have been dealing with the following differential equations: \frac{d \mathbf{m_1}}{dt} = \gamma_1 \mathbf{m_1} \times \mathbf{B} - \frac{n_{2}}{\gamma_{cr}} \mathbf{m_1} + \frac{n_1}{\gamma_{cr}} \mathbf{m_2}...

Hey folks, I'm reading the paper: http://arxiv.org/abs/hep-ph/0301168 and I'm trying to make sense of the first line of eqtn 44 where he states that we can write: \frac{1}{2}\sum \int\frac{d^{2n}k}{(2\pi)^{2n}}log(k^2+\frac{m^2}{L^2}) as...

Homework Statement Basically, my task is to find out the internal resistance of a solar cell. I set-up a circuit as seen here (http : / / mt14 . quickshareit . com / share / picture666d18 . png), and measured the Current and Voltage on different settings of resistance in 5Ohm intervals from...

Homework Statement A particle of mass m is moving along a path composed by two two quarters of circumference of radius R (see attached picture). The spring acting on the particle has a known constant equal to k and an equilibrium length equal to R (the radius again). Due to friction, on the...

http://www.englishrussia.com/?p=251 Those look like mammalian herbivore chompers. I'm thinkin' marine mammal. Manatee? Elephant seal? (Frankly, it looks to me like the Flower-Power singer-chick from the Muppet Show.)

Homework Statement I need to show that \Sigma\frac{1}{nlnnlnlnn} from n=27 to n=10^(100,000) is approximately equal to 8.1

I was playing around with Euler's identity the other day. I came across something that seems contradictory to everything else I know, but I can't really explain it. I started with e^{i\pi} = -1. I rewrote this as ln[-1] = i\pi Multiplying by a constant, we have kln[-1] = ki\pi...

I'm just curious to find how what this integral is, but more importantly how it's computed. I've looked at the method that the sophomore's dream integrals are computed with and they do not seem to work here, I get to a step where I'm evaluating a sum from x=0 to x=\infty. Here's the integral...

The letters A-M = 202, therefore N-Z = ? This is the whole problem. It's driving me nuts. Help? =(

Homework Statement Q] A particle of mass m is moving in a circle of radius r. The centripetal acceleration(a_c = Kt^2), where K is a positive contant and t is time. The magnitude of the time rate of change of angular momentum of the particle about the centre of the circle is...

http://www.scsun-news.com/news/ci_7938886

I recently got a stronger prescription for my glasses, and I now notice something strange. If I look at an object, say my computer screen through the left edge of the left lens, the left side of the screen will be red, while the right side will be blue. This happens for any object the is...

Is there a proof or disproof that any given finite string of digits will occur somewhere in Pi?

Ok, so there is this strange phenomenon that I have experienced several times before. I want to know if anyone else here has had this problem or if they have any idea what it might be. AS A RESPONSE TO THE ABOVE DISCLAIMER: I will not consider any response as a diagnosis but as of now the...

How can we proceed to prove the following identity ?

First off, sorry if this is the wrong forum to post this, general is the only thing I think can fit here. Hello all, This is my first post. From this you should get an idea of what I am like. This is not an attention whoring post but a legitimate question that's been bugging me for quite...

I mean like one day...I some how proved that a girl's attraction to a guy is directly proportional to the amt. of money he has and proportional to how much game he has...btw these things arent taken seriously

Homework Statement A sheet of aluminum is 1 um thick. A thick copper ring of radius b is placed on the film, and a (smaller) copper disk, of radius a, is placed on the film at the centre of the ring. The disk and ring are connected to the terminals of a battery, so that current I flows through...

Hello to all, I'm reading one article about LT (low temperature) GaAs MSM (metal-semiconductor-metal) photo switches that has application in ultrafast sampling. Basically, there is one photoswitch in series with hold capacitor. Special test is performed which gives electro-optical signal...