Weird Definition and 469 Threads

The first thing is that it gets discrete spin states. Ok so we filter out a spin up state |+> and then send it through a perpendicular Apparatus then act surprised that we got |-> states back, isn't that what precession does? the only weird thing I can think of is that even after precession we...

someone took video of this thing over Tainan in Taiwan, is there any known natural explanation to ummm, holes in the sky? [url]_jEBrT-roJU[/youtube]

Here's the weird limit: lim n\rightarrow \infty aCn/na = 1/(a!) Don't ask how I thought this up, but let me explain my reasoning. Let's say that a=3. Then aCn = (n)(n-1)(n-2) And because n is approaching infinity, could it be (n)(n)(n) = n3? I wouldn't normally think of things like this but...

Okay, so I know C=Q/ΔV And ΔV is the sum of the electric fields multiplied by the distance between the charges, so if the first charge has a charge of Q and the other has -Q with R distance between, the electric potential/voltage is: ΔV = [(kQ/r^2) + (kQ/r^2)]R so ΔV = 2kQ/R. And C = Q/ΔV...

http://www.teacherschoice.com.au/maths_library/area%20and%20sa/area_2.htm "NOTE: The value of p can never be known exactly, so surface areas of spheres cannot be calculated exactly." p = pi here. It always irks when people say "(insert irrational constant here) doesn't have an exact...

Right now I'm watching a US Public Broadcasting Corporation television program entitled: "The Linguists", in which a man (I think he was from Africa, but I'm not even certain of that, as I wasn't even listening until the math stuff surfaced), explaiined his integer progression, which was quite...

I'm a second year Comp E student, and in an intro class we're learning 8085 assembler. The professor wrote his own simulator for the class, but it's kinda buggy and I feel like it's been given minimal updates since he wrote it some 15 years ago. I was looking for a programming project, so I...

Homework Statement I've implemented RSA and just need to print some stats and write to files.Homework Equations My solution works fine when I provide an input file, however, if I let it read from standard input there is no output written to either of my output files. Reading works regardless. I...

i'm using an android smartphone it takes really clear pictures and when u zoom in it shows the picture in great detail and clarity and I'm very pleased with this feature. however, recently i took two pictures and when i tried to zoom in while viewing them they suddenly turned into another...

Hello, I recently used Matlab to find the natural frequencies of a clamped-clamped beam. It was fairly simple, as I construct the global mass and stiffness matrices. Then it's just a matter of using the eig() function. (For sake of simplicity I put beam properties all to 1.) When I choose how...

Homework Statement Show that f(x) = \sum_{i=1}^{\infty}\frac{2^{i}x - \lfloor 2^{i}x \rfloor}{2^{i}} is continuous at all real numbers, excluding integers. The Attempt at a Solution I've tried going about via |f(x) - f(y)| < ε, but am having trouble with this, since first, I don't get anywhere...

Derivation of expansion scalar for FRW spacetime -- weird observation In a recent thread... https://www.physicsforums.com/showpost.php?p=3567386&postcount=137 ...I posted a formula for the expansion scalar for the congruence of "comoving" observers in FRW spacetime. When I posted, I...

Homework Statement Two springs are hung in a "v" shape, and a 500g mass is attached to the point of the v. One spring is observed to stretch 9mm, the other 23mm. Students are NOT permitted to measure any angles, before or after the weight is attached. Is it possible to...

Hello again everyone! I would like to ask a question regarding this Hamiltonian that I encountered. The form is H = Aa^+a + B(a^+ + a). Then there is this question asking for the eigenvalues and ground state wavefunction in the coordinate basis. The only given conditions are, the commutator...

Over here: The tutor started writing all over my math book in pen to demonstrate a problem! Why would a tutor do that? Especially to a perfectly clean new unmarked book that you may want to sell.

My book tries to illustrate the conditional expectation for a random variable X(\omega) on a probability space (\Omega,\mathscr F,P) by asking me to consider the sigma-algebra \mathscr G = \{ \emptyset, \Omega \}, \mathscr G \subset \mathscr F. It then argues that E[X|\mathscr G] = E[X] (I'm...

Hi there, I'm taking some measurements of a wireless signal using InSSIDer 2.0. Sometimes the signal fluctuation is upwards of 20 dBs, and sometimes the fluctuation is almost nothing. It is a very short range signal. There is minimal fluctuation in the signal shown when I'm 10 metres...

I know this may sounds silly but I am confused consider this two form for example, by substitution, I get \omega = dx \wedge dy = d(rCos\theta)\wedge d(rSin\theta) = r dr \wedge d\theta also consider this smooth map F(x,y)=(rCos\theta,rSin\theta) then F^{*}\omega = rdr \wedge...

if a gas expands isothermally but irreversibly from V=1litres to V=2litres under constant external 1atm pressure, if i want to know the workdone by the gas, should i be using 1) WD = integral pdV = nRT ln V or 2) WD = pexternal(Vfinal-Vinitial) i realize they give different...

In the capacitor association a) and b), calculate the equivalent capacitance Given: area = A, vacuum permissivity = E, distance between each plate = d[PLAIN]http://img714.imageshack.us/img714/7073/semttulojznw.jpg In the first I've calculated the capacitance of AB, AC, AD, BE, CE, DE...

Hello everyone! I'm new here and I've checked this forums once in a while for physics information, mainly astrophysics stuff but I usually found all the answers I needed. Not this time though. A bit about me. I'm an Indie game developer and the game I'm working on takes place in a...

Homework Statement Now that I'm working it out as I'm typing it, I think I may have solved this problem; could still be a mistake though... This was an extra credit problem on the final for my into to diff eq class. I never saw anything like it before and I didn't finish it because I got...

So, I would like to start off by saying I know how time works and accept it for what it is, but have a curious question about it. So we all know that 60 seconds make a minute, but how can we tell when exactly a second passed? Let me explain ( this is all hypothetically of course): We...

Hello. This is my first post here and I come shamelessly looking for help. I'm an Electronic Engineer and have an idea for an invention but do not know if the type of material that is needed exists, the only one I can think of so far is Bread dough. Anyway, what is needed is something...

I am told to write the value of a the derivative at a certain point next to each function. And to find the point/s f(x) = x2 f ' (x) = -6 so I figured I just do f ' (x) = 2x f ' (-6) = 2 x (-6) = -12 But they tell me the answer is (-3, 9)

Homework Statement This is a problem I came up with when I was doing something similar in Spivak's Calculus; although a simpler version. Suppose, we have f(x)=x^3 and g(x)=x^2 find \lim_{x\rightarrow \infty} f(x)/g(x) Homework Equations N/A The Attempt at a Solution...

What's the symbol in the attached image, that looks like a right pointing arrow, but with a short perpendicular arrow at the base? The book is 'Mathematical Logic' by Cori and Lascar. They don't explain what it is. Maybe it's the symbol for function?

I need help with solving this weird equation... What is: \left[ z^{n} \right] (ln(1-z))^{2} / (1-z)^{m+1}?

http://img849.imageshack.us/img849/9697/physicsy.jpg The system bodies shown in the figure is released from rest. Assuming all the contacts to be smooth, find the acceleration of each block (mA = 14 kg, mB = 11 kg, mC = 50 kg) This problem from Problems In Physics by Abhay K. Singh...

I've got a 555 timer wired up like in this picture and my output is going to 2/3 Vcc instead of Vcc. This is leading to problems as I have hooked into a decade counter down the line which gets the low timer output and it's output shrinks as well. Any ideas on what I should try?

Homework Statement http://img69.imageshack.us/img69/281/trap01.jpg AC and AC both equal 13. The given angles are in the pic. The Attempt at a Solution Attached. Why do I get angle ADC 70? It doesn't make visual sense, and I was told by a very smart person to always trust my visual cues! So...

Hi everybody. Not very good in solving DE's. Here is one for the better: ay'+by = (y'+cy)^2+d where a,b,c and d are real positive constants. I know that : y(0)=0 and y''(0)=k*d (k= real positive constant) Any possible suggestions? Thanks Pachito

Homework Statement I'm doing a review for a Mechanics exam I have tomorrow and this first problem given on the review struck me as odd. Problem Statement: An 89kg boat that is 6.6m in length is initially 7.1 m from the pier. A 27 kg child stands at the end of the boat closest to the pier...

triple product is given by A.(B x C) = B. (C x A) = C. (A x B) so why is ∇.(F x G) = [∇ x F].G - F.[∇ x G] ? if i let A = ∇, B = F , C = G, then ∇.(F x G) = - F .( ∇ x G) = G.(∇ x F) its as though they carried the 3rd term over to add to the 2nd term ?

Hi there, this is a not a homework question but rather question about the theory behind this problem. Say if someone asks you to calculate the number of moles in 20 ml of a 1M NaOH solution, I would usually say it is going to be 20 mmol as you do 20 ml/1000 ml/L x 1M = 0.02 moles = 20 mmol...

I have this weird oscillation coming from my circuit. its a wheatstone bridge with a single strain gage. I am using The PST 4130 from Omega Engineering to supply +10vdc. When I first turn it on the signal is pretty clean, but after a while, it turns into this...

How is MM doing the integral? Is this something with a definite solution? Limit[Integrate[(1 - 2 x)/x^2, {x, a, b}], a -> 0] Integrate[(1 - 2 x)/x^2, {x, 0, b}] The first one gives infinity, the second a closed solution, though technically they should be the same, right?

Hello 2 all ! I am a student on electrical engineering, and i have the following problem to solve: Homework Statement An electrical circuit includes a dc voltage source with an internal resistance, and a load resistance. Determine the value of the load resistance R (with a precizion...

Homework Statement Show that a2+b2 =>2ab, and hence, if x+y+z=c, show that x2+y2+z2 => 1/3 c2 Homework Equations The Attempt at a Solution How to prove this when we only have unknowns? The only thing i can think of for the first one is a (a+b)2= a2+b2 +2ab, but how to prove that a2+b2 =>2ab...

So, the definition of Laplace transform is: \int_{0}^{\infty} e^{-st} f(t) dt what if: f(t) = g(t)exp\Big[-\int_{0}^{t}g(t')dt'}\Big] Or, in words: if the function being transformed is itself a function of an integral. This seems somewhat tough, but maybe I just...

http://www.spaceweather.com/submissions/large_image_popup.php?image_name=Michael-French-swirlyICE_1296508078.jpg" These are pretty cool looking. Any theories as to how they form backwards from the braided wire?

Hi, I am a Master's student in mainly theoretical physics. When I studied in my Bachelor's, I really didn't enjoy the examns very much: I had a systematic clockwork learning style for preparing myself for the examns. The result is that I usually get the desired (very good) grade, but...

Homework Statement Solve for n: 2n.Cos^2(n)=1000 The Attempt at a Solution So, I think there's a substitution involved here. I tried to rearrange cosine in terms of sine to make it into a quadratic but that didn't work. I've gone through all the table trig identities. I've had other...

Homework Statement I swear this is the weirdest question I've encountered: If the South polar ice cap melts completely due to global warming, then what do you expect to happen to the length of the day? 2.Choices a. It will get slightly longer b. It will get slightly shorter c. It will...

Homework Statement \int (x+8)/(x+4) Homework Equations N/a The Attempt at a Solution I tried to split the problem which resulted in: \int x/(x+4) + \int 8/(x+4) But now I'm stuck,and this is a bonus question on my AP Calculus homework.

http://img522.imageshack.us/i/0108111458.jpg/ I found this weird mechanical device in the woods near my house. There seems to be some kind of serial number on it that reads, "DY6-6" http://img828.imageshack.us/i/0108111753.jpg/ It also says, "MADE IN USA" on the other side. The flywheel...

Why can't our eyes focus on that one type of deep blue Christmas lights? It always appears fuzzy from a distance, even if another bulb right next to it appears in focus.

Edit: Nevermind, I figured it out! I jumped the gun in making this post. I'm doing another problem from Schaum's Outline: Basic Circuit Analysis. The problem, #3.24, and its solution are found in this...

Take a look at these videos: Smoke rings in air: http://www.swisseduc.ch/stromboli/etna/etna00/etna0005video2-it.html?id=14 Air rings in water: http://www.youtube.com/watch?v=bT-fctr32pE&feature=related Second one is really amazing, as it shows two things: - great stability of the ring, which...

Hi all,SUM of Series from n=2 to infinity of: 1 ------------ (2^n) (n-1) This question is driving me bananas... my tools are Telescoping or Geometric series, but neither seem to work: I've tried everything to get this into a geometric series form and then using the a/1-r formula, but...