Convention Definition and 184 Threads

Homework Statement I doubt that is the following notes (in the first picture), correct or not? Because i couldn't find any proof in the other book... Homework EquationsThe Attempt at a Solution Can I say that consider σ positive to right and τ positive downward, orientation (θ) clockwise as...

Homework Statement I don't understand why the sign of moment of beam at left (clockwise) and moment at the right of beam (anticlockwise) are considered as positive... Why we can't assume the clockwise moment as positive and anticlockwise moment as negative? Homework EquationsThe Attempt at a...

Homework Statement http://nptel.ac.in/courses/112107146/22[/B] in the notes, the author define upward shear force as positive (LHS) , he take downward shear force as positive as positive (RHS)? Homework EquationsThe Attempt at a Solution why the author didnt fix downward shear force as...

A simple doubt came to my mind while browsing through logarithmic functions and natural logarithms we define $$\log_b(xy) = \log_b(x) + \log_b(y)$$ Here why is the condition imposed that b>1 and b is not equal to zero and that x and y are positive numbers? Is it something to do with the...

Hi, I derived Raychaudhuri Equations in both (- + + +) and (+ - - -) sign conventions from metric. In Robert Wald and Sean Carroll books, (- + + +) sign convention and I derived correctly in that Sign Convention as given in the books. In the other convention, I am having one sign difference in...

The condition for a stable orbit is given by (3.42), where ##V'## is the fictitious potential energy (potential energy of the corresponding fictitious one-dimensional problem) and ##r_0## is the radius of the circular orbit. The result ##n>-3## is obtained by using the convention that positive...

Hello. I'm new to this forum. I'm starting a PhD – it's going to be a big long journey through the jungle that is CFD. I would like to arm myself with some tools before entering. The machete is Cartesian Tensors. I know the rules regarding free suffix's and dummy suffixes, but I'm having...

Homework Statement The question tells me that all dissolved iron species will have an activity of 0.1M. So is Fe(OH)42- considered a dissolved species of Fe, and if so, it will have an activity of 0.1M? Homework Equations N/A The Attempt at a Solution I want to say that it is not considered...

Okay so after reading various books on sign conventions for work I am told by my teachers that in chemistry,work done on the system is positive while work done by the system is negative while in physics it's the exact opposite I only use the former convention And modify the first law of...

Hi there, Over the last couple of weeks, I have been learning about the relativistic description of electromagnetism through Leonard Susskind's Theoretical Minimum lectures, and although I have managed to follow it, there are some parts which I am becoming increasingly confused by, not helped...

In the derivation for equation 24-2 in the picture below., the line integral was chosen along a path anti-parallel to the field lines. As a result, cos(180) = -1, which made the integral for the voltage positive. However, in examples 24-2 and 24-3, the line integral is also taken as...

If the work done by an electric field is N, then the work done by me will be negative N? Perhaps this applies if I move a charge against the field lines, but what if I move in the same direction?

So I have been following various derivations of the FRW metric and have a bit of confusion due to varying convention... Would it be correct to say that curvature K can be expressed as both K = \frac{k}{a(t)^2} and K = \frac{k}{R(t)^2} where k is the curvature parameter? If so, is it correct to...

I am currently reading "Differential Equatons with Applications" by Ritger and Rose, and I need some clarification about some notation and convention that they are using. I think it all stems from a lack of clarity of the difference between the operator d/dx and the "object" (I don't know what...

When writing ##A_{a}\text{ }^{b}## one means ''The element on the a-th row and b-th column of the TRANSPOSE of A" right? Such that ##A_{a}\text{ } ^{b}= A^{b}\text{ } _{a}## ? I would just like a confirmation so I'm not learning the convention in a wrong manner.

Why is it not just dE = q + w because I assume if you use general sign convention and take work to be negative when it is done by the system and positive when it is done on the system, you should get the right answer. Silly question but I'd appreciate some clarity on this formula please?

In physics book, if work is done by the system, it is positive in my chemistry book, if work is done by the system, it is taken as negetive. when I asked my chemistry teacher, he said the sign convention is different in physics and chemistry. but why are they different?

The Passive Sign Convention from Wiki: "In electrical engineering, the passive sign convention (PSC) is a sign convention or arbitrary standard rule adopted universally by the electrical engineering community for defining the sign of electric power in an electric circuit. The convention defines...

I am reviewing in Griffith's E&M, and I find that potential is defined as zero at infinity (that bits fine). However, should not an object that distance from a charge be less than zero (negative) if it is closer than infinity? It seems it should as it has lost P.E. However, he doesn't seem to...

Homework Statement I have the following equation Aab= c ua ub Where Aab is a rank 2 tensor and ua is a vector and c is a scalar and a,b = {0,1,2,3}. I know both Aab , ua and ua I want to find c explicitly but I don't know how to interpret or calculate c = Aab / ( ua ub ) Does anyone...

According to Wikipedia:http://en.wikipedia.org/wiki/Hilbert_space the inner product \langle x | y \rangle is linear in the first argument and anti-linear in the second argument. That is: \langle \lambda_1 x_1 + \lambda_2 x_2 | y \rangle = \lambda_1 \langle x_1 | y \rangle + \lambda_2 \langle...

In the link given below http://science.uvu.edu/ochem/index.php/alphabetical/g-h/haworth-formula/ In step 3 last line it is written that 1 and 2 both represent D glucose,but how?As penultimate carbon no 5 has H on right side rather than OH,so it should be L glucose.

I have come across the dielectric constant represented by two variants of epsilon. Is there any convention behind the two variants such that: \varepsilon is the SI Dielectric Constant \epsilon is the CGS Dielectric Constant or does it really depend on the writer and how frisky they feel?

Homework Statement Q.[/B] A body dropped from a height H above the ground strikes an inclined plane at a height h above the ground. As a result of the impact, the velocity of the body becomes horizontal. The body will take the maximum time to reach the ground if : (a) ##h=\frac H4## (b)...

Problem statement I'm trying to understand how passive sign convention works, and how to read the voltages/currents direction in a circuit. For different set of voltages and currents I'm trying to calculate power. I'm using the picture below as a reference. a) i=10A v=125V b) i=5a v=-240V c)...

Homework Statement I am having trouble understanding PSC. Please help on this question. Teach me like I am 5. My tutor couldn't break it to me. (SEE ATTACHED) and find whether the power is being given or taken Homework Equations p=vi p=-vi The Attempt at a Solution I can't...

I am looking for a way to connect the Condon-Shortley-Wigner to the Edmonds phase convention. Specifically I am writing a program to compute Wigner-d matrix coefficients From tabulated values (e.g. even Wikipedia) d^1/2_{1/2,-1/2}=(-1)^{-1/2-1/2}d^1/2_{-1/2,1/2}=-sin(theta/2) So...

In the course of solving the simple harmonic oscillator, one reaches a fork in the road. x(t) = A1Sin(wt) + A2Cos(wt) At this point, you exploit a trig identity and arrive at one of two solutions x(t) = B1Sin(wt+phi1) or x(t) = B2Cos(wt+phi2) Both of these are correct solutions...

From an exercise set on the summation convention: X and Y are given as [Xi] = \begin{pmatrix} 1\\ 0\\ 0\\ 1\end{pmatrix} and [Yi] = \begin{pmatrix} 0\\ 1\\ 1\\ 1\end{pmatrix} There are a few questions involving these vectors. The one I am stuck on asks to compute XiYj . It may be necessary...

I know about chemical and physical differences between Solution and Colloid, but I can't find anywhere what is the right naming convention for Colloid substances. Let me explain: For Solution we have: Solute dissolved in Solvent called a Solution. For Colloid we have: "1st...

Homework Statement The Attempt at a Solution I'm having trouble understanding how r1 = -1.5j and r2= r3 = 0. Can anyone make this a little clearer for me? I've spent quite a while trying to wrap my head around it but to no avail.

With Δt = γ ( Δt' + v Δx' ) For calculating delta t for stationary twin with values of traveling twin. Is it conventional that velocity (v) outbound is positive and distance (x') is negative. Then at turnaround point sign of velocity changes to negative. And for inbound v is negative and...

Homework Statement I am having a little trouble using mesh analysis. I'm trying to stick rigorously to the passive sign convention, as I'm told that this is sensible. Consider the circuit diagram attached, where I have added the mesh currents in orange. In red are the polarities for the...

Please see the attached pic.

Homework Statement let a_{i}=x^{i} and b_{i}=1\div i ! and c_{i}=(-1)^{i} and suppose that i takes all interger values from 0 to ∞. calculate a_{i}b_{i} and calculate a_{i}c_{i} Homework Equations i know that in suffix notation a_{i}b_{i} is the same as the dot product as when you have to...

Homework Statement I am wondering about the following conventions: The work done by the gas is positive if the gas expands, and negative if it is compressed. Conversely, the work done on the gas by external force (e.g., a moving piston) is positive for compression, and negative when...

Homework Statement This is a problem I made myself, I was curious to see if I'm understanding this convention properly. The link: http://gyazo.com/24c7f7f82f6453a3396d96d67c2a067d Homework Equations ##P=IV## The Attempt at a Solution Okay, from what I understand, the power...

Heys guys, I asked a similar question in one of the previous threads and therefore I apologize if anybody is offended or thinks I'm asking too much. I just want to clear and define some concepts in my head. So it is agreed that simultaneity is a convention and that in SR inertial frames...

Homework Statement Find Vad and VebHomework Equations voltage drop, KVLThe Attempt at a Solution I actually did: Vad -24V - 4V + 6V = -22V but this is wrong.I know going the other way Vad: 6V + 8V + 12V = 26V, because it is only drop, and plus to minus on drops means they are...

Do you normally write the magnitude of the vectors in free body diagrams? I have homework on this. Is there any convention when writing the magnitude?

Hello, The electric potential is defined as: $$ \phi(\vec{r}) = \int d^3r' \frac{\rho(\vec{r}')}{|\vec{r} - \vec{r}'|}. $$ My question is, for solving for the potential inside of a charged solid sphere (constant charge density) by using the above equation I get, $$ \frac{Q}{2R} \bigg(...

Hi, sorry if this is in the wrong place, not really sure whether it should be homework questions or here! I'm writing my final year paper and frequently mention mesons and quarks by their symbols and am unsure whether I should be italicizing them? My latex package for writing them easily...

This is a bit embarrassing, but by convention does |0> = (1,0)^T and |1>=(0,1)^T, where we are in the basis of the eigenvectors of \sigma_{z}?

I googled for lens formula's proof on the internet and found one here http://www.tutorvista.com/content/physics/physics-ii/light-refraction/convex-lens-formula.php The problem is that during the course of derivation, it is assumed that image distance is -u following the sign convention...

Hi Guys. I'm hoping that you might be able to help me out with a question I have about anti-particles in Feynman diagrams. I'm drawing these again for the first time in over a decade because I'm teaching an elementary physics course that requires the students to draw diagrams for a few...

The summation convention for Tensor Notation says, that we can omit the summation signs and simply understand a summation over any index that appears twice. So consider a 3X3 matrix A whose elements are denoted by aij, where i and j are indices running from 1 to 3. Now consider the...

Homework Statement I am reading a chapter on semi-conductors in a text.It talks about n-p type semi-conductors and states that "the potential of the n-side is higher than that of the p-side" However, by convention, in case of batteries for example,we designate the negative terminal as lower...

Greetings, This is just an opinion question about notations. Having learned the basics of bra-ket notation and using the ESC, as far as I can tell, ESC is just plain better, at least when dealing with finite bases. Using bras and kets, you can represent and manipulate states using...

So, I realize the basic theory behind Einstein Summation Convention is that any repeated set of indices implicitly indicates a sum over those indices. However, what if an index is repeated three times? For example, my mathematics professor posted this problem: εijkajaj = ? As you can...

Could anyone give me a link that explains or simply explain to me how the dot convention on the mutual inductance works? For example, I'm trying to draw an equivalent circuit that converts the dots into voltage sources of this circuit...