Connection Definition and 520 Threads

{****not a homework question****} This question has a slightly different theme than the typical torque and inertia problem - I have to determine stress on a bolt. A steel block of mass M is bolted to the rim of a slowly rotating steel disc of radius R whose axis is horizontal; the rotating...

Hello everyone: I am trying to find a program or formula that will help me figure out how many windings, turns of coil, are needed per coil on a 6 coil steel stator ring powered by 3-phase AC power to get a certain magnetic field strength, about 1.3T. Is there any way that you could help me...

Hello everyone: I am trying to find a program or formula that will help me figure out how many windings, turns of coil, are needed per coil on a 6 coil steel stator ring powered by 3-phase AC power to get a certain magnetic field strength, about 1.3T. Is there any way that you could help me...

I just read a sentence in GRAVITATION by MTW (aka the "Princeton Phonebook") that made me realize a confusion wrt the metric, connection, and curvature. In short how are g_{\mu\nu}, \Gamma^{\alpha}_{\mu\nu}, and R^{\alpha}_{\beta\mu\nu} distinguished? They all include the description "how space...

On a low-voltage DC Solar system(up to 48V nominal), should I leave the lines floating or one should be grounded? I don't see any real advantage on any option...that's why I ask to confirm

So let's say for example there is a slide with two slits on it infront of a screen. A beam of electrons is aimed at it. A) What would happen to the size of the fringes on the screen if I decreased the spacing between the slits B) What would happen to the fringes if I moved the screen...

In a lot of textbooks on relativity the Levi-Civita connection is derived like this: V=V^ie_i dV=dV^ie_i+V^ide_i dV=\partial_jV^ie_idx^j+V^i \Gamma^{j}_{ir}e_j dx^r which after relabeling indices: dV=(\partial_jV^i+V^k \Gamma^{i}_{kj})e_i dx^j so that the covariant derivative is...

Now I'm just start to study the Kaluza-Klein theory from http://arxiv.org/abs/grqc/9805018. I try to calculate the Einstein Field equations in 5 dimensional vacuum space-time. we start with 5D metric tensor, \hat{g}_{AB}=\begin{pmatrix}...

I have a question about the nomenclature of the "spin connection". To me "spin" implies quantum mechanics. However, as I understand it, the spin connection is just a part of the covariant derivative of a vector that is written in tetrad (i.e., local frame) components. So isn't the "spin...

hi guys, I want to know if it is always possible to link two transformers in series with different rated voltage. And if there is any concern about the polarity. If it is not possible in which conditions it can be done?

Recently I've been doing some research in physics, and I've come across a problem: what exactly is the connection between General Relativity and gravitons? I know that General Relativity talks about the bending of spacetime and how that causes gravity, and that the graviton is supposedly the...

Hi! I just registered as I have been wondering quite a while about a specific question that grew in my head while reading about electronics in school. As I have learned voltage is a difference in potential. So if we have a 9V battery there is a difference of 9V between the two poles of the...

If the proposed Higgs field is a mechanism which "decelerates" certain particles (whereas not interacting with others), thus creating mass as we know it, would it follow from this that the field is also, ultimately, the source of gravity? If so, there seems to be a connection between gravity and...

Hi, I'm struggling to grasp the physical reason behind the fact that, in a curved spacetime, a change of metric implies, in general, a change of connection, i.e. if I have two metrics g_{ab} and \hat{g}_{ab}, in general \nabla_a \neq \hat{\nabla}_a. Besides this, is there any relationship...

Homework Statement If you were given an enclosed box, containing two 2000uF capacitors, which were either joined in series or in parallel, suggest, with a reason, how you would determine which way they were connected. Homework Equations C = C1 + C2 in parallel 1/C = 1/C1 + 1/C2 in...

Hello :smile: I am wondering about something. Why when I 'hover' over the windows connection icon in the system tray it is showing this: What does that speed mean? Because I am downloading something right now and it is certainly not downloading at 54.0 Mbps This is the actual...

A (3-d or higher) metric which is flat except for one non-trivial metric function of a different coordinate - eg changing dx2 to f(y)dx2 in Euclidean or Minkowski metric [but not f(x)dx2] - is curved if f(y) has a non-zero second derivative; there is no way to make the f(y) 'disappear', ie to...

Hi. I have been looking at differential forms, and that inspired me to consider a partial derivative as a ratio between cross products. Please tell me if the following makes sense. Say we have cartesian coordinates (x,y) and polar coordinates (\rho, \phi). I want to calculate...

I am familiar with changes that occur with capacitance and ESR when you connect supercapacitors in series or in parallel. My question is along those lines, but the answer is elusive to me... From schematics I have seen about supercapacitors imbedded in circuitry, the supercaps always have...

As it suggests, the problem I face is to how I carry about an Earth connection (for an AM radio transmitter set I made) instead of burying it into the ground? Of course, if I make a radio set, I simply can't carry it about making an Earth connection into the ground. I have provided a solution...

First off, let me say that while I am an avid astronomer, I know very little about the mathematics of astrophysics. My specialty falls more under mechanical engineering. While initially they may not seem all that related, history shows that the mixing of varying disciplines often sparks...

In a few days, people from my ISP are coming to my house to install super-fast fiber optic internet. Right now, I am using a DSL, or about a 3-meg connection speed. According to what I've heard, a fiber-optic network connection can give up to 20 megs. I use my computer for gaming, especially...

Hi all! Anyone knows where to find, online or on a book, the affine connection for the schwarzschild metric? Thanks

Homework Statement A 10 cm * 10 cm * 10 cm box contains .01 mol of nitrogen at 20 degrees C. What is the rate of collisions (collisions/s) on one wall of the box? Homework Equations \frac{N_{coll}}{t}=\frac{NAv_{x}}{2V} v_{rms}=\sqrt{\frac{3k_{B}T}{m}}The Attempt at a Solution I'm really...

Let E = span{v1, v2} be the linear subspace of R3 spanned by the vectors v1 = (0,1,-2) and v2 = (1, 1, 1). Find numbers a, b, c so that E = {(x, y, z) of R3 : ax + by + cz = 0} I tried doing this question, but I am totally lost. I know that any vector in E can be represented as a linear...

I have posted a similar problem not long ago.This time, I am trying to find a connection between 3 concepts that would possibly lead to the answer to the problem. I have heard that there is a way to find the probability of getting a particular sum by rolling multiple six-sided dice at the...

I'm reading about emission spectrums, and my text says that when an iron bar is heated until it's hot and glowing, the "warmth of the glowing bar represents the infrared portion of its emission spectrum". Is it true that radiating heat is associated only with infrared EM waves? ~Jules~

How well off are you in physics if you're pretty good at math? This is probably an attempt to rouse my self-esteem but it seems like I'm pretty good at math (doing an introductory analysis/calculus course, think Courant and Spivak) but I really, really suck at physics.. How can this be? maybe I...

Hello, I was curious about the following point. I know that if a function is monotone, then it is one to one (meaning for x1 != x2, then f(x1) != f(x2) ). But what about the converse? I can't seem to think of a counter-example.

Homework Statement Capacitors of 11.1uF and 1.9uF are charged as a parallel combination across a 333V battery. The capacitors are disconnected from the battery and from each other. They are then connected positive to negative plate and negative to positive plate. Find the resulting charge on...

What is the connection between spherical packing and lattice structures of atoms or molecule? For example, i can't see any relationship between spherical packing and the structure of graphite..

I wonder how much information about metic tensor of Riemmanian manifold can be extracted if only the Levi-Civita connection is given. Conversly, if the metric on manifold is given there is formula for Christoffel symbols which define connection so there exists only one symetrical metric...

I have to determine the 18 connection coefficients \Gamma_{ij}^{k} for spherical coordinates. I know how to calculate said coefficients, but I'm not sure what all 18 are. Can anyone clarify what the possible combinations could be?

Can anyone help me on this question: Under what relation between vector fields X and Y, the Levi-Civita connection of X with respect to Y, \nabla_{Y}X is 0? Any answers or suggestion will be highly appreciated.

Hello Friends I need little help pleasezz :redface: How Can I solve this circuit? Which things first I have to find. And how. Problem Statement is. A. Average power of each phase load and total Load. B. Determine the reactive power of each phase and total reactive power C. Find the...

Getting "connection reset" errors Today I've had several errors when following links around the forums, but refreshing the page works immediately. The error occurs immediately (not like a timeout) and the "errors details" say that the connection was reset by the server. Here's what Google...

As of today, every time that I hit the 'edit' button on one of my posts, Safari crashes. Is anyone else experiencing such annoyance? This has never happened before, but I just downloaded the Safari 4 upgrade. Any connection that anyone knows of?

Hi! I'm having kind of a "little" problem. I got an old program written in Fortran77 and I want to implement some functionality from Fortran90 routines. The routines are quite long, so I'm not able to rewrite them in F77... Is there a possibility to connect the routines so that they can...

Good afternoon! To build a serial connection of two transformers, four coils are used: Two of this coils have n1 turning, two of them have n2 turnings. The coils are built together in the way, you can see on this picture: http://img197.imageshack.us/img197/2698/transformer.jpg The...

two AC power sources -- connection? i am working on a control system for a compressed air energy storage system for a wind turbine (generates ac). the goal is to shave peak power consumption, so at night the compressor will charge (either by the wind or by the grid), and during peak hours, it...

who can help me with this: on an ellipsoid most points are not umbilic, but there are some special places that are. Discuss how to find these points and their connection to lines of curvature.

In covariant derivative, we have a quantity called affinity. The book says: When defining an affine connection, a coordinate frame must first be selected and the choice of the components of the affinity is then arbitrary within this frame. However, when these are all determined, the component...

Hi all, 1. the max. speed of waves in the air is the speed of sound. it's caused by the physical limitation - changes in the air fabric (particles) can't propagate faster in it. 2. so I was wondering, whether the max. speed in our space isn't limited by the max. (indivisible/atomic) change...

Homework Statement I'm supposed to make a connection between SU(2) and SO(3), by using U=\frac{a_0+i\vec{\sigma}\vec{a}}{a_0+i\vec{\sigma}\vec{a}}, where \sigma are the usual 2 dimensional Pauli matrices. I need to find the corresponding axis and angle of rotation in three dimensions, in...

Hello friends, I've been reading Schiff's book on QM (3rd Edition), esp the section on the WKB approximation. (This isn't homework.) I have a few questions: What is the physical significance of the arrow on the connection formulas, like \frac{1}{2}\frac{1}{\sqrt{\kappa}} e^{-\zeta_{2}}...

My (new*) linux system is having trouble connecting to most websites. Originally I thought it was a DNS issue, because I can connect to some websites (Google, thanks goodness, and physicsforums of course), but now I'm not sure. What do you think this is? Is it me, my connection, or an...

I wasnt quite sure where to put this thread. This question occurred to me while I was looking at the group theory of standard model groups so I thought I'd put it here. Anyway, here is my question: One can define the Killing form for a group by taking the trace of two generators. One can...

I am reading a book which says that if the components of the connection vanishes then the torsion and curvature tensors vanish. Now, I understand how this happens with curvature tensor, but I don't see how torsion tensor would vanish. Torsion tensor: \tau (X,Y) = D_X (Y) - D_Y (X) - [X,Y]...

I wanted to ask if there is any connection between the SU(2) group for the spin 1/2 and the gauge group of weak interactions. I feel there isn't much of a connection other than the fact that they share the same group properties, but I am not sure. Thanks to anyone in advance that can clarify...

Searching for the "Human Connection"--Physics and Music. Hello everyone! I'm currently a senior in high school (going off to study architecture at either Rensselaer Polytech Ins., Marywood U, or Philadelphia U) and am doing an independent research project on the topic of relating acoustic...