Mistake Definition and 296 Threads

Dirac Matrix Property? Possible Book mistake? Derive KG from Dirac I got a copy of QFT demystified and on pg. 89 he says he can write \gamma_{\nu} \gamma^{\mu} = g_{\nu \sigma} \gamma^{\sigma} \gamma^{\mu} = g_{\nu \sigma} \frac{1}{2} (\gamma^{\sigma} \gamma^{\mu} + \gamma^{\mu}...

Homework Statement http://img854.imageshack.us/img854/6386/vbbvbbvbbvbb.jpg Ic = Ie Veb = 0.7 volts Homework Equations http://www.allaboutcircuits.com/vol_3/chpt_7/8.html The Attempt at a Solution A resource I'm relying on claims that...

The single most common obstacle to understanding cosmology is probably the picture of expansion as an explosion outwards into empty space from some central point. It's a mistaken picture instilled in the public mind by popular media channels and reinforced by time-honored slang: the misleading...

Can't figure out my mistake in calculating volume I'm trying to calculate the volume of {(x,y,z)|x^2+(y-1)^2<1, 0<z<\sqrt{4-x^2-y^2}}: \int_0^{\pi}d\theta \int_0^{2sin(\theta)}\sqrt{4-r^2}rdr=\frac {-1}{3}\int_0^\pi ((4-4sin^2\theta)^{3/2}-8)d\theta=\frac{-8}{3}(\int_0^\pi...

Homework Statement The problem says: A mine provides a transport ystem constiting into carriages (of neglect mass) hanging on a riel free of friction. In a specific moment two people of mass m=45kg are traveling when one of them says his breaks are not working. In that moment he was at...

Suppose that X_i\sim N(0,1) are iid, then by the Strong Law of Large Numbers the sample mean \bar{X}_n=\frac{1}{n}\sum_{i=1}^n X_i converges almost surely to the mean, which in this case is 0. Recall that by definition, \bar{X}_n \to 0 almost surely means that...

What's the mistake here? hehe http://a7.sphotos.ak.fbcdn.net/hphotos-ak-snc6/64102_341098562596296_100000884664248_973353_615500462_n.jpg

Homework Statement http://img818.imageshack.us/img818/4065/thvs.jpg The Attempt at a Solution Calculating the Thevenin Resistance there I get 16Ω - the book however says it's 3Ω. The way I see 3Ω being calculated is if 4Ω were in parallel with 6Ω + 6Ω - however they all appear to be in...

problem: switch of LR circuit is closed at time = 0; what is ratio of inductor's self-induced emf ( E(L) ) to battery's emf ( E(bat) ) at t = 2τ? my solution: switch is closed so current begins to build up according to equation: i = (E(bat)/R) (1-e^(-t/τ) ) multiplying R on both sides and...

I hope you don't mind if I'm a little liberal in your cute format. I'm looking for why method 1 does not equal method 2. 1. Homework Statement : Method 1--the "cute math" method. Alright, so... I have a circular loop of radius A, let's place it in the xy plane, with a steady current I...

I have 100 on every assignment/test in my DE course. Today, I took one quiz out of many (of which 2 are dropped) on using Laplace transforms to solve equations. I have done dozens of these problems, with great success. Today, the quiz was 2 problems, both of which relied heavily on the fact...

Hello, I have been changing my major many times over and am trying to figure out what I should do. I started out as a biology major, then went to business, back to biology, then to engineering, and now I'm thinking back to biology. I took the physics for bio majors and did fairly good, and I...

Do I made a mistake in writting this formulas. I don't see them. Tnx for your answer. V1=(Kps*(1-ra**2)*(1-cos(6.2831853*y(1))))/(6.2831853**2* (1+ra**2+2*ra* cos(6.2831853*y(1)/2))**2) V2=(Kps*ra*(1-ra**2)*(1-cos(6.2831853*y(1)))*...

Homework Statement Mass m sits on a frictionless, horizontal table. Assume: - All vertical forces acting on m (such as gravity and the normal force) sum to zero. - All applied forces act parallel to the table When a force of magnitude F is applied to mass m, it accelerate at magnitude a...

Homework Statement In this video from which there is a screen shot above the author went from x/2 to 2x and all he said was half is two quarters. right a half is two quarters it is not 2. I just want to make sure that he made a mistake because I've been seeing some real bizarre things in...

Hi, At my school physics 2 has calculus 1 as a prerequisite. You don't have to take calculus 3 while taking physics 2 or prior to taking it. I found physics 2 to be extremely difficult. I was taking while taking calculus 2. We got into flux integrals, Gaussian surface integrals, and some...

In book Modern theory of critical phenomena author Shang - Keng Ma in page 17. \sigma_{\vec{k}}=V^{-\frac{1}{2}}\int d^3\vec{x}e^{-i\vec{k}\cdot\vec{x}}\sigma(\vec{x}) \sigma(\vec{x})=V^{-\frac{1}{2}}\sum_{\vec{k}}e^{i\vec{k}\cdot \vec{x}}\sigma_{\vec{k}} Is this correct? How can inversion of...

For a function f(x), I have to determine intervals of increase/decrease, find local max(s)/min(s), and find intervals of concavity. The first thing I'm doing in this is to write out f'(x) and f''(x). f(x) = ln(x)/\sqrt{x} For f'(x), I used the quotient rule and received f'(x) =...

Homework Statement It is asked to write \frac{M_{0}}{\sqrt{1-\frac{c^{2}}{v^{2}}}} in lowest terms. The answer that's given is: \frac{M_{0}*c\sqrt{c^{2}-v^{2}}}{c^{2}-v^{2}} The problem is that I don't get the correct answer.The Attempt at a Solution My solution: (0)...

Homework Statement http://img85.imageshack.us/img85/6346/missrd.jpg Across the axis of a steel rod act 3 forces: F1 = 80 kN F2 = 50 kN F3 = 30 kN Crossection area of rod = 4cm2 What are the forces that are being made a the different parts of the rod, and what will be it's overall...

Its a mistake to pursue for Physics honors in India ! Hi.. It is Arnab aka Esteban-Pato... I m doing Physics honors under the university of Calcutta, India and is in my 1st year... The tremendous passion towards Astrophysics and Cosmology from my very childhood has attracted me to take...

Hi guys, Please can someone look at this working (see attached). The equation in question is [43]. It is highlighted with a red border. The numerical answers in the pdf are correct and have been verified against published material. That being said, I believe there must be a problem...

I sent an E-mail to my professor Kaufmann, but I made a mistake on his name. I typed Kaufman, not Kaufmann. What should I do?

Mesh Current: Cannot see my mistake in my approach? Homework Statement Find currents I1, I2, and I3 using Mesh Current Analysis in this circuit: Homework Equations KVL The Attempt at a Solution Initial equations: Mesh 1: -120 + 20k(I1) + 40k(I1 - I2) = 0 Mesh 2: 40k(I2 -...

This is the answer key to one of my quizzes If you notice in the question, see attachment, were it says to integrate with respect to y the integral is integrating from 0 to 25 but this produces a negative area so this is technically wrong, yes? You don't just simply integrate from the lower...

Greetings! I’m a long time lurker; so let me apologize off the bat for popping in here with my first post being a request for advice, I’ll try not to ramble too much. Two years ago the idea of "changing course" on the direction of my life came up. I pushed the idea aside, assuming my...

why does the prof wrote a mistake there and wrote 2cos theta in there ?? (i didnt typed the question correctly,the original is i need to calculate the integral on the volume enclosed by z>=0 and the sphere which is written in the photo.) how mathematicky can i get this transition...

But if this is so, then in these photographs: http://en.wikipedia.org/wiki/Bubble_chamber http://en.wikipedia.org/wiki/Cloud_chamber the "particle track - line of bubbles" shouldn't be able to be photographed so defined, but blureness should be photographed instead, since-if no lens was used...

Homework Statement http://img860.imageshack.us/img860/6320/tthing.jpg In the drawing is described a beam structure fixed at point C, and held by a cable BD to the floor. The beam is loaded by two concentrated forces, F1 and F2, as described in the drawing. Given F1 = 700 [N] F2 =...

This was my circuit, and they asked me to find the potential between a and bI had no clue how to combine the voltages, I stupidly added them...but the weird thing is that they appear to both contribute to the main voltage and counter each other! I feel really bad now because I'm sure I made a...

1. An elevator is moving upward with constant velocity V. We consider a frame of reference fixed to the elevator. Since it is not accelerating, our system is equivalent to, say, a frame of reference fixed to the ground (there are no inertial forces). Now, we are inside the elevator and let an...

Lee 2003: Introduction to Smooth Manifolds ( http://books.google.co.uk/books?id=eqfgZtjQceYC&printsec=frontcover#v=onepage&q&f=false ) (search eg. for "computational"), Lemma 12.10 (b), p. 304: where I is an increasing multi-index: (i_1,...i_k) with each value less than or equal to all those...

Hello everything follows up well, but when I compare the result (eq. 5) with the numerical solution of eq. 1, then are different. Where is the mistake? eq. 3? thanks

I was worried that I will not find a job this summer, so I took the first offer I got. (freshmans and sophomores, please don't make the same mistake, evaluate all other possible actions) But the more time I spend doing my job, I realize just how far away from what I intend to do this job...

Something that can't be right about eigenvectors--where is my mistake? Xs are eigenvectors, lambdas are eigenvalues, and Cs are constants of integration. If we rearrange some homogeneous higher-order system into a matrix equation, we get the first equation on the word document. The solution...

So I got everything right other than Rd (the end). I personally think there's a mistake in the solution manual. Homework Statement Basically these are all pin joints, even the "hydrolic cylinder" (CD) is weightless and connected by pin joints, so the fact it's called or drawn as...

I very desperately need some advice from you guys. This has been eating me up inside for the last half a year. Here's the situation: I'm a computer science major with one year to go before I get my BS. I find computer science interesting, but I'm not very passionate about it. I basically...

Homework Statement A particle executes simple harmonic motion along a straight line with mean position at x=0, period 20s and amplitude 5cm. The (shortest) time in seconds taken by the particle to got from x=4cm to x=-3cm is? The Attempt at a Solution Let the equation be x=Asin(wt+Φ)...

Basically I need to find a mistake in this "proof". I claim that 0,1,2,3...are all even. I will use induction to prove that 'n is even' for n = 0,1,2,3... Base case is n = 0, which is true, 0 is even. I assume that the statement is true for n = 0,1,2,3...,k and consider n = k+1. By...

Homework Statement Force R that acts on point O, is the combined force of two forces: Q that's applied horizontally, and F, whose line of action is along OB. (I think it ought to be an arrow there instead of a line)... Calculate Q and F, if R is 550 [N]...

that is too sad it have been 2 days and i coudnt find out where do i make mistake. i wanted to prove:" (f(x)*g(x))'= g(x)*f(x)'+ g(x)'*f(x)". so: (f(x)*g(x))'= lim h→0 ((f(x+h)*g(x+h)-f(x)*g(x))/h) =lim h→0 ((f(x+h)*g(x+h))/h) - lim h→0 (f(x)*g(x))/h) =[lim h→0 ((f(x+h))/h)*lim h→0...

Homework Statement http://www.khanacademy.org/video/2-dimensional-projectile-motion--part-3?playlist=Physics Skip video to 4:40. He says that the average velocity in the horizonatal direction is the same as the initial velocity (7.07m/s) because it doesn't change. but wouldn't the velocity...

Homework Statement I'm given an equation Ax + By + C = 0 The answer in the back says: If B not= 0, the set is the graph of f(x) = (-A/B)x + (-C/A) How can the last term be (-C/A)?? Shouldn't it be C/B ? Homework Equations The Attempt at a Solution y = (-Ax - C)/B...

**Really think there is a mistake in my textbook. Please check Hey, this specific equation we are to figure out requires us to use sampling methods, and then to calculate a bunch of different equations, however before the equation I noticed my textbook has a mistake. Please correct me if I...

Hi all, I am a current physics undergrad student. I recently got a position on a research team doing several different biophysics research projects. Since I am just an undergrad, I get to start out doing basic low-level work like running image analysis algorithms. I am getting a little...

Homework Statement Find the inverse laplace transform. (see figure attached for question as well as my attempt) Homework Equations The Attempt at a Solution I came up with a different answer than the given solution, and I can't figure out where I went wrong. We are given a...

Homework Statement Please review the attachment. Why can L be OUTSIDE of D ? x_n \in D and D is bounded. So doesn't that mean that any subsequential limit of x_n has to be in D ? Btw, Theorem 3.10 is Bolzano Weierstrass. Theorem 4.4 Says that A continuous function on a closed interval is...

When mass M is at the position shown, it is sliding down the inclined part of a slide at a speed of 2.07 m/s. The mass stops a distance S2 = 1.85 m along the level part of the slide. The distance S1 = 1.23 m and the angle theta = 33.9 degrees. Calculate the coefficient (mu) of kinetic friction...

[PLAIN]http://img408.imageshack.us/img408/6862/mistakeg.jpg Am I reading this wrong, or does this sequence not converge? There is no k dependence in the summation, so we can take out the 1/n1/2, and the summation of 1 from k=1 to n is just n, right? so that gives n*1/n1/2-2n1/2=...

Suppose an object of mass 'm' is attached to a vertical spring of spring constant 'k' and slowly lowered to the equilibrium position. We have to find the extension in the spring. I have two approaches- 1) At the equilibrium position, force due to tension in the spring and weight of the...