Weird Definition and 469 Threads

Hey all, so I don't even know how I managed to find this, So I'll walk you all through how I've spent my last couple hours. I've been studying intro calculus, and I recently came across the chain rule. I was screwing around with finding the derivative of various functions like the square-root...

My laptop has been driving me nuts for the past 28 hours. Weird things are happening when I try to use the mouse. For example, when I've just logged in (Windows 7), the mouse is always in one of these two modes: 1. Mouse actions work on the desktop, but not on the taskbar. 2. Mouse actions work...

Homework Statement A block of mass m = 1.5 kg is launched from point A with speed VA = 12 m / s, in the circuit shown in Figure 4. If we assume that there is no friction determine: a) the speed of the block when it reaches the point C; Drawing of the problem: http://i.imgur.com/TrcMJ5I.png...

We're attempting to measure the immunogenic affects of a particular molecule after subsequent acid and base treatments. As a first version, we're keeping it simple. After all treatment and neutralization, we wind up with 400 uL 0.2 N HCl + 400 uL 0.2 N NaOH + 200 uL H2O. We are getting massive...

Homework Statement Homework Equations V=IR Kirchoffs Current Law The Attempt at a Solution I picked the middle node (the one surrounded by 3 resistors) as my reference. V1 and V2 are my other two nodes. I'm also assuming that V1>V2, V1<reference Using Kirchoffs Current Law: (Node 1)...

I noticed that there is another thread on this, however my situation is a bit different in that I am only a junior so it is very possible I will be asking these professors for a letter of recommendation again. I think that a gift card or something similar would be a bit inappropriate (though I...

Hi! Two exerts from my lecture notes: "Assume we have a system of point masses in position ##\vec{r_i}## which are influenced by forces ##\vec{F_i}##." "Let's say you have a system where ##\vec{F_i} = - \nabla_i V##" In the second line, what does the notation ##\nabla_i## mean? Why is that...

Homework Statement Consider a square hill barrier produced by a 10V potential. Incident upon this barrier is a steady stream of 5eV electrons. (a) If half the electrons are transmitted, how thick is the barrier? (Please derive the transmission probability rather than merely quoting it.)...

Homework Statement Before anything, please address this first question: Angular momentum, at least for pure rotation, is defined about the axis of rotation only, correct? [/B] We are given a wooden ring of mass M, radius R. I place a small particle of mass M on its circumference. Now the wooden...

Hi everyone. I'm new to this forum and I'm an Italian engineering student. By navigating in other forums, I've often heard of people that one can happen to find in scientific faculties, and that one can find "weird" (Of course not all people studying in scientifc faculties are weird, only just a...

Is antimatter time-reversed negative matter? If so, then it would behave like ordinary matter electromagnetically BUT Newton's grav would yield like mass charges attract and unlike masses repel. Ie, a combination of antimatter and matter does not make a diametric drive due to the time inversion...

Apparently we still need spinors for the Dirac equation in 1+1 dimensional space-time. Do spinors still do "funky" weird stuff in 1+1 dimensional space-time? Thanks for any help!

In Srednicki's text on quantum field theory, he has a chapter on quantum Lorentz invariance. He presents the commutation relations between the generators of the Lorentz group (equation 2.16) as follows: $$[M^{\mu\nu},M^{\rho\sigma}] =...

Hi guys, I'm having a hard time with that one from Cohen-Tannoudji, ##F_{VI}## # 6. I'm translating from french so sorry if some sentence are weird or doesn't use the right words. 1. Homework Statement We consider a system of angular momentum l = 1; A basis from it sub-space of states is...

I managed to stumble while typing pretty fast, and hit some key combination that put me into a weird paragraph-view type mode for the e-mail messages that I compose. See the screenshot below. I've tried searching Outlook help for "hotkeys" and "paragraph view" and similar, but no luck so far...

Hello, I am in desperate need of help with setting up this problem and I would very much appreciate being steered in the right direction. 1. Homework Statement Find the mass percent of Fe3+ in a 0.0293g sample of iron ore if 13.25 ml of a .200 M stannous chloride solution is required to...

Is it weird that I find physics II easier than physics I? I am currently in Physics II at university and flying through it with an A. However, I took Physics I at Community College and BARELY got a B. On my tests so far this semester I got a 87 on the first one and a 97 on the second one. In...

I saw on the news that Obama was going to visit Beijing pretty soon, and got to thinking...why does China have so many more people than the USA, when ostensibly, as the worlds melting pot, we should be the "Times square" of the planet and attract the greatest volume of planetary (even galactic)...

Homework Statement Not homework, but I don't really know where else to put this. Below is some code and it's relevant output, but the output is what I'm concerned about. Homework EquationsThe Attempt at a Solution #include <stdio.h> #include <stdlib.h> void foo(int a, int b) { int r =...

You are given a cone with height/length "L" and radius R. This cones Length is parallel to the Z axis in an XYZ frame of reference while the radius is parallel to the XY-plane. This cone is then revolved(spun) around the y-axis, graph the area "touched" by the cone on the YZ-plane. I am...

So, a while back i read about this idea, but i can't find it anymore, so i was wondering if anybody else knows about it. here it is: We know that if a vector field is conservative, then there exists some surface whos level curves are perpendicular to the vector field. or inversely, that the...

Hello there physicists! Here are two questions I'd like you to answer please. If the population keeps increasing and if we keep building infrastructure, could the Earth's diameter decrease? In other words, could we crush the Earth like crushing a tin can in the palm of our hands? Surely the...

Y=x^(2/3) and y=x^2 rotated about the x=4. First I equate the equations giving me x=0,-1,1. The problem is I have exactly 2 graphs that are symmetric in respect to the y axis. N I have not encountered a problem in stewart dealing with this. I know that the volume on the right side of the...

Hi, I got this instruction given: > For each of the following three scenarios, initially assume that the East-West traffic has had a green traffic light for a long time. 1) If a North-South car is detected then the traffic lights will cycle to green in that direction. The walk light will...

I'm a bit curious about this. To make the poll a bit more scientific (:-p), let's use a common definition of "Weird": Behaving eccentrically, being socially inept and/or otherwise non-conforming to ordinary social norms, but all this to a moderate degree (so nowhere near insane, but still quite...

Is there a formula for Gaussian integrals of the form $$\int_{-\infty}^{\infty}{x^n}{e^{-a(x-b)^2}}dx$$ I've looked all over, and all I could find were formulas saying $$\int_{-\infty}^{\infty}{e^{-a(x-b)^2}}dx=\sqrt{\frac{\pi}{a}}$$ and...

Hi, I recently designed a PCB in EAGLE, and I got it manufactured and I had all the pieces Sufrace Mounted on it, put it in the oven, everything seems fine and dandy, but I already killed 3 LEDs because of some weird thing going on. I have 5 different LEDs conneced to my circuit, the leds run...

Homework Statement Hey guys, Here's the question. For a distinguishable set of particles, given that the single particle partition function is Z_{1}=f(T) and the N-particle partition function is related to the single particle partition function by Z_{N}=(Z_{1})^{N} find the following...

if a rigid body, let's say a disk,is floating in space and we exert a force outside its center of mass will it rotate or just start a linear move? its center of mass is free to move.sorry if my English are not so good.I hope that you understood the question

Can someone explain this please?? Weird pulley with Tension Homework Statement See attached picture for problem Homework Equations n/a The Attempt at a Solution The answer is B. No idea why. Any help would be appreciated. Thanks!

Hi Could anyone give me a hint on getting a closed form for the following integral: \int\frac{1}{k + sin(x)}dx where k is a constant. Thanks. e.

Homework Statement Find, using l'Hôpital's rule: lim x-> ∞ ((tan(ax)-atanx)/(sin(ax)-asinx)) Where a is a non constant greater than ± 1. Homework Equations -The Attempt at a Solution I can't work out anything from this point. I don't know how to change or factorize the expression (is there a...

Very weird luminous bed sheet ?? I spent the night at another place yesterday. At night, the bed sheet (which was a bit "plasticy") would shine intense greenish light when I run my hands over it. The light sometimes converges to a specific point, as if there was an LED placed underneath...

Hello, While riding home today, I started to wonder what was the definition of a second in the context of time. I looked it up and found out that the definition has changed somewhat over the years and it is now defined as (paraphrased) 9,192,631,770 periods of the cesium atom. A meter is...

Weird probability problem..."With what probability is it raining?" Came across this the other day looking at interview questions. Suppose you want to determine whether it's raining in a distant city. You have three friends there who you can call and ask about this. Only thing is: Each...

[b]1. Homework Statement Apond initially contains 1,000,000 gal of water and an unknown amount of an undesirable chemical. Water containing 0.01 g of this chemical per gallon flows into the pond at a rate of 300 gal/h. The mixture flows out at the same rate, so the amount of water in the...

Here's a video: https://www.youtube.com/watch?v=iHtIPbYK_EI I have been able to do this for as long as I can remember, and only on my right hand. The action that I do to trigger this thing involves pressing my 4th finger onto my palm. Doing this doesn't hurt even if done continuously...

Homework Statement Figure P4.31 represents the total acceleration of a particle moving clockwise in a circle of radius 2.50 m at a certain instant of time. At this instant, find (a) the radial acceleration, (b) the speed of the particle, and (c) its tangential acceleration.Homework Equations...

So I'm doing a Beta Spectroscopy of Sodium and apart from the Energy Spectrum, I'm intending to use the Kurie Plot to incorporate the Coulomb Correction Factor F(Z,p). But when I try plotting the data, my K(Z,p) has an incredibly huge number, on the order of 1020 and the linear graph looks...

Given: a ~3W monocrystalline solar panel, originally from a panel+battery+light pack from early 90s, spent a decade in a box, then a decade on the roof under the sun and elements, unconnected to anything. I wanted to finally put it to some use. The circuit is straightforward - the panel...

I was looking at an example where it was evaluating a closed loop integral of a vector field around a triangle (0,0) (1,1) (2,0) by using greens theorem. This example was in the green's theorem section of the book so green's theorem must be used. Anyways the double integral was set up as follows...

Let me try to explain. If I take a reel of movie film, I can unwrap it see different frames simultaneously. How ever if I were "trapped" in the movie I could only experience one frame at a time. Now this example is not a direct proposition I am making. It''s just to imagine a higher...

I've been reading & watching videos about the double slit experiment, and I'm failing to see what's so interesting & strange about it (I hope someone can enlighten me on what I'm missing). The weirdness is NOT the fact that observing an electron changes it's behaviour (right?) At first I...

Homework Statement Verify that \int_{ℝ^n}exp(-\frac{λ}{2} \langle Ax, x \rangle-i \langle x,ζ \rangle )dx=(\frac{2\pi}{λ})^{\frac{1}{2}}(detA)^{-\frac{1}{2}}exp(-\frac{1}{2λ} \langle A^{-1}ζ, ζ \rangle ) where A is a symmetric matrix of complex numbers and <ReA x, x> is positive definite, and λ...

Hey everyone, I have built a circuit which includes a PIC. The logic is that if a specific pin gets a logic 1, the output pins will be activated and LED lights will flash. I am controlling the input pin with a magnetic reed switch. It was working great few days ago. However today the output...

Well, the question is not weird, but the circumstances are. I am not a physicist, and I am not studying physics. I am a student at a university, and quite interested in physics, but I am intentionally keeping myself away from taking any more physics classes. I like to be able to imagine...

I have a N-ch Mosfet load switch that connects to a WiFi module on a circuit board. When the switch is turned OFF, I still see a voltage of 1.4V at the load. Ckt attached. I decreased the bleed resistor from 1k to 100 ohms. The off voltage decreased to 1.1v. This doesn't happen with other...

Hello friends, I noticed from Wikipedia the following information: Atomic radii: 4th period(only d-block elements): Sc:160 pm Ti : 140 pm V : 135 pm...

Hello all, I'm not really a programmer at all, but I learned c++ for a while so I can do basic stuff. Having just finished my linear algebra class I suddenly had an urge to write myself a simple matrix solver. I knew it wouldn't be easy (especially because of my lack of skill) but I was...

I was attempting to solve the following problem from IIT-JEE 1991 (actually I first found it on the book Solved problems in Physics) It asks for the image viewed by an observer at left. Ok, an observer at left would seen an image that passes through a spherical dioptre glass-air only...