Difficulty Definition and 261 Threads

Let r_{\mu} be a tensor in coordinates x^{c} and R_{b} be a tensor in coordinates X^{c}. Then let r_{\mu} = 0. Then {\partialX^{\nu}/\partialx^{\mu}}R_{\nu} = 0. I read in a book that one can divide both sides of the last equation by the partial derivative to get R_{\nu} = 0. I do not...

Homework Statement I've been trying to get this code to work: ode45(@(t,y) fallode(t,y,B), [0, tmax], [31330, 0]) Homework Equations function dy = fallode(t, y, B) % ODE function to model a fall over a large range of % altitudes, reaching up to high subsonic Mach numbers. % y(1) is...

Could anyone give an insight as to how difficult a statistics major is? My college doesn't offer any probability classes until the junior year, so I'd have no way of knowing what it's like until then. My fear is that I'll wind up taking all these prereqs and end up hating or not understanding...

I have a little trouble solving Electrostatic problems (at undergraduate level) that involve volume or surface integrals when there are normal vectors involved, and one must (normally) dot this with a vector field (such as electric field) when one cannot use Gauss's law. one such example I...

I am learning about tensors. Is gαβAβ the same as Aβgαβ ? Thanks for any help.

Hey! I had a discussion with a group of professors recently about the different disciplines one can master in electrical and computer engineering. There seems to be a prevailing notion that the closer one works to the physical layer, the harder his job is. Most of my professors seem to...

Hey guys, So I want to simply pose a question. Conceptually, which is the hardest area of science to grasp? This can also be a sub category of a discipline...or anything like that. I'm just curious because I am a PhD student in Math, but my area is actually Mathematical Physics. So I...

Hi, I'm having difficulty trying to figure out the following question, I don't know how to even start it. Any help would be appreciated The question is, wave Pulse travel with the same speed down two wires made of different metals. The wires are stretched between the same two supports. If the...

Hello friends, I have this problem I'm having difficulty with, it reads - simplify the following expression ( ( x + 2 ) / (x^(2) - 2x) ) - ( (x) / (x^(2) - 4) ) it wants me to simplify it into ( 4(x + 1) ) / ( x(x - 2) ( x + 2) ) I can't get it to...

I'm going through a calculus textbook in an attempt to learn it myself. So far so good, but I've been stuck on optimization problems. I understand the concept. The maxima and minima of a function can be found by looking at where its derivative = 0. I also see that a function that has no...

I am having difficulty with choosing a major: Physics or Electrical Engineering(Micro&Nano)... Physics becuase every concept is like doorways to understanding life! I like be theoretical and imagining possibilties. All physics interest me so i wouldn't know what i want specifically until...

I am very confused as to what type of books are appropriate for my level of mathematics. I am trying to learn Abstract Algebra myself so I am reading from Artin's Algebra. Unfortunately I am having a lot of difficulty understand the proofs he presents in the book. So am I right to say this book...

I am in high school, currently studying grade 12 Physics. Other subjects I am taking are Chemistry, Biology, Calculus I, English, History. Out of all these subjects, I find that I have to study for Physics the most. It is a hard class. The exams seem to be much much harder than the homework and...

Homework Statement Let S be the part of the plane z=f(x,y)=4x - 8y +5 above the region (x-1)^2 + (y-3)^2 <= 9 oriented with an upward pointing normal. Use Stoke's theorem to evaluate the surface integral for the vector field <2z, x, 1>. Homework Equations Stoke's Theorem is surface...

Very Difficulty Differential Equation ... (x+y)dx + xy dy=0 . Please Solve This Problem ?

Ive run into some residue problems, I can't seem to find a clear answer anywhere on this... I need to find the residue of exp[i.kx] / [ 1 - k^2 ], where k is my complex variable, and x is positive. I have poles at 1 and -1 in my integral. Now everywhere I look, a pole of order n is when...

I'm trying this problem on allaboutcircuits too. However they havn't been as helpful as this board is for other problems (mostly mathematics). Homework Statement I have been given an assignment which is part of, what I consider, the most difficult part of electronics engineering. Circuit...

My question relates to a subject I took last semester, which since then I have found out that a lot of students failed and complained that it was too hard and the lecturer wasn't satisfactory. The university has since removed that lecturer and simpified the content and the assessment pieces. Is...

1. The operator is: [ 0 -i] [ i 0] 2. I'm trying to find the eigenvalues and vectors. By inspection they appear to be |i> = (0) ...(1) and |-i> = (1) ...(0) (or, easier to type, <i| = ( 0 1) and <-i| = (1 0) ) But these values don't work when I plug them...

I'm taking this 400 level astrophysics course next semester, and I'm not sure what sort of difficulty level to expect, since I'm unfamiliar with the material. Any ideas? The course listing in the calendar reads: "Basic space plasma pheonema: the Earth’s plasma and field environment; the...

MATLAB "quad" and difficulty with vector input Hello all. Consider the following: function y = testf(x,a) y = sin(pi.*a.*x); ...and then we have a = 0.05:0.05:1; result1 = quad(@(x)testf(x, a),0,1) which crashes with ? Error using ==> times Matrix dimensions must agree...

What do I do if I have a hard time contributing in labs? Everytime my professor tells us to work together on a lab, I always walk away feeling like it was a wasted learning experience because I couldn't contribute. Additionally, labs are hard for me because there seems to be a huge mentality of...

Homework Statement Find the implicit form for the plane that contains the origin and the line: L(t) = <1+t,1-t,2t> The Attempt at a Solution' So, the point P = (1,1,0) and vector v= <1,-1,2>. To find the implicit equation for the plane using the form ax + by + cz = d , I will substitute...

Homework Statement Given that \sum^{n}_{k=0} x^{k}= \frac{1-x^{n+1}}{1-x} Obtain a similar result for ; \sum^{n}_{k=1} kx^{k} \sum^{n}_{k=1} k^{2}x^{k} The Attempt at a Solution Hey, well basically my trouble with this question stems from the manipulation of the limits and the effects...

Homework Statement Calculate the radius of convergence of \sum_{n=0}^\infty a_{n}z^{2n} let \sum_{n=0}^\infty a_{n}z^{n}with radius R Homework Equations \limsup|a_n|^{\frac{1}{n}}=\limsup |\frac{a_{n+1}}{a_n}|The Attempt at a Solution...

Hello everyone, I am really new to electronics and have been reading Electronics for dummies, and am readying myself to move on to something a bit more sophisticated. Something that has been hard for me understanding is circuits that don't seem to have a start or an end. I do quickly...

I have difficulty understanding "Modulo"? What is its meaning? a\equiv b\left(mod n\right) means a is "congruent" to b "modulo" n means a-b=knExcept accepting this is an equivalence relation, I feel very uncomfortable about "modulo" because of the lack of visual picture of this concept...

Homework Statement I am worried that I don't understand a basic part of figuring out the component forces in the following problem. I have a full worked example but there is a few steps which I don't understand why we use sin for the x component and not cos (understand why I am really...

Homework Statement An 80mm aluminium alloy piston fits into a cast iron cylinder with a uniform radial clearance of 0.75mm at 15C temp.the piston and cylinder reach 120C. 1. Determine radial clearance at 120C 2.what is diametral clearance 120C 3.What is change in cross sectional area of...

Hello, ladies and gentlemen! For the 2010-2011 academic year, I will be a Senior Physics major at my university. Before I ask my question, I need to present some information for you. I have taken some of the following courses in the math/physics sequence: - Differential Equations - Linear...

i have an equation 0.02q=T1-T2 how do i plot a graph between T2 and T1...since all the three are variables i am not able to plot the graph between T2 and T1...kindly help...is der any method to approximate variable q to a constant? so dat i can plot the graph

Homework Statement Hi everyone, I am taking 'Mechanics' ( Introductory level - Calculus based ) this summer. I already passed my Calculus I ( Differentiation ). The textbook we are using is " Physics for scientists and engineers" by Serway. I am facing some difficulties with learning. I...

Integral of unknown difficulty! Homework Statement integral of: 1/[4+5sin(2x)] dx The Attempt at a Solution U substitution on 2x gives u=2x then du becomes 2dx so... du=2 dx after that, i get 1/2 * int of: 1/[4+5sin(u)] du from here, using v=5sin(u) then: dv=5cos(u) du this...

Although I have completed my high school and I will be going to college, there is one thing that i really regret about my high school and that is my weakness in solving permutation and combination problems i never had a proper guidance and whatever i could gather from books I tried and yet would...

I really like physics, however I'm worried about not being able to get a 3.8+ gpa (looking to go to a top med school) if I major in it. I'm also going to be attending a really good undergrad school so there will be much more competition in my classes (having a near 4.0 gpa in high school is...

A model of tank fluid temperature (fixed mass inside) based on the mixing of two streams, one hot and one cold, each with fixed temperature, the hot one a fixed flowrate and the cold one an oscillatory flowrate can be expressed as: du/dt + [c1 + c2*(1+cos(t))]*u = c1 The solution can be...

Homework Statement Had an optimization test today and had a problem with this question. I needed to find the stationary points of this function: f(x)=\sqrt{x^{4}+1}-x+3 The Attempt at a Solution So you differentiate that puppy with some chain rule for the square root part and tidy up you...

One of the topics in my linear algebra course is kernel and range of a linear transformation. I have a firm understanding of what the kernel is: the set of vectors such that it maps all inputs to the zero vector. Range, however, remains nebulous to me. My textbook says that the range is "THe...

Intermediate algebra and algebra 1 are both 5 units and then college algebra is only 3 units, so is college algebra easier then since it is only 3 units ? (At a 2 year college)? going from algebra 1 to algebra 2 (Is there much difference in the level of difficulty between the two?) or going...

Homework Statement Homework Equations The Attempt at a Solution What I am unsure of is how to find the derivative of u. Since the original integral is integrating with respect to y, should I be finding the derivative of u with respect to y, and treat the x's as contants?

Hello, Perhaps you could help me out. I am having trouble intuitively understanding the result of the following problem: A piece of wire is cut into two pieces. One piece is bent into an equilateral triangle, the other is bent into a square. Where should the wire be cut to yield the...

If we have a resonator composed of 2 partially transmitting mirrors/grids and we excite the resonator from one end, say the left side then on the right we expect to get the characterstic transmission comb and on the left the inverse (1-Transmission) reflection curve. Whats giving me a...

The non-relativistic Larmor formula for the power radiated by a point charge is proportional to the charge’s acceleration squared. When the charge’s velocity and acceleration are collinear, the radiated power is proportional to gamma^6 times a^2. If the charge has simple harmonic motion, say x...

Hi, I've been studying from Spivak's Calculus. Normally when I have trouble I can just search, but this time I can't find anything (you can tell how extensive this forum is in that I've been registered here for a while and this is my first post). On page 89, the book gives proof of the...

There is lots of talk about how hard Organic Chemistry is, so I ask, what did you think of Organic Chemistry if you took it, and how did you excel at it if you did? What were your weaknesses?

Homework Statement A 43.4 kg, 3.2 m uniform ladder leans against a frictionless wall.* A 88.6 kg person is standing on the ladder down 1.18 m from the top of the ladder.* The ladder makes an angle of 53 degrees with the horizontal.* What is the minimum coefficient of static friction between...

Homework Statement Find the speed of an Earth satellite whose orbit is 400km above the Earth's surface. What is the period of the orbit. Homework Equations The first part was pretty easy. I used v=[(Gm)/r]^(1/2) to get the answer. The Attempt at a Solution For the first part, I...

Homework Statement A newspaper reported an attendance of 15,000. If you assume that this number contains two significant figures, how many people could actually have been at the game? The Attempt at a Solution I'm having difficulty answering this problem not because I don't know how to...

Why can't I get audio for "Quake"?

How difficult is Spanier's Algebraic Topology text to understand? How about the exercises?