Hard Definition and 1000 Threads

A recap for those that missed my past threads: I am a physics major with 1 course requirement to graduate. Last year I applied to a few grad schools and several dozen internships, research programs and any and all remotely technical jobs that would assist me in getting experience, which would...

Is there a number "a" such that limit of ((3x^2 + ax + a + 3) / (x^2 + x -2)) as x approaches -2. I have attached a picture of this problem for those who need a visual aid and a side for "hints". I have been trying to solve this question with limited success.

Hi, I love the cognitive sciences. Indeed, for the last few years, what's been motivating me to work hard in school has been almost exclusively my dream to lead a life deeply mired in the mysteries of the mind/brain. I haven't gone a waking hour in an extremely long time when I haven't thought...

I've been having a problem lately with my computer. It's running 64-bit Windows 7, and has two external hard drives plugged in. Occasionally , I've noticed that sometimes when I attempt to do something in a program, even something as single as right-click on a cell in Excel, the computer will...

I'm trying to find the equilibrium size of a planetesimal which is made of a material whose density is pressure dependent. (quite a mouthful) I have to solve this differential equation: y(x^2y''+2xy')+2y^2+bxy'=ax^2y^3+(xy')^2+by where a and b are constants.

Hi. I just came back from the registrar and dropped the complex analysis course I was failing. I don't think I slacked off. True, it's the summer and I had a few kickbacks with my friends that I wouldn't have had during the academic year, but I really wasn't doing much else besides complex...

Hello, My problem refers to hard tyres, so assuming none or very little lateral deflection. For a particular tyre on a particular floor there is a rolling resistance against the movement when the tyre is rolling. In a simplified case the resistance can be approximated as a rolling resistance...

I was having some free time and decided to do some mathematics from my high school mathematics book.These two problems remained, and I am completely clueless to the solution approach. Homework Statement A. If sin(θ)-cos(θ)=1, prove that sin(θ)+cos(θ)=±1 B. If tan(θ)+sec(θ)=10, prove that...

Hello guys I am trying to solve the integral of cos(x) squared, i.e. (cos(x))^2, but not using the trigonometric identity of this function, but using integration by parts. I tried turning it into 1*(cos(x))^2, but I didn't go too far, maybe did something wrong. Am I on the right direction ...

The question as follows: Hypothetically, there are 158 grade 12 students at FLC High School, 92 have enrolled in Data Management, 71 have enrolled in Advanced Functions, and 40 have enrolled in Calculus. The math students include 14 who are taking both Data Management and Advanced Functions, 18...

Homework Statement We have a 2 unstable particles moving in the ##\scriptsize xy## frame. The leading one has speed ##\scriptsize u_2=0.99c## while the other has speed ##\scriptsize u_1 < u_2##. When the distance between them is ##\scriptsize 100m## in the ##\scriptsize xy## frame they both...

Hi all,:) I saw this post 10 Photos That Definitively Prove Math Is Really, Really Hard days ago and found it so extremely amusing so I want to share it here and I hope you'll find this hilarious as well!;)

There are lots of examples of numbers where "is it a rational number" has been an open question for a while before being proved as not being rational. Pi and e being famous examples. Some of them are still open, like pi+e, or the Euler-Mascharoni constant, but I think the general consensus is...

Homework Statement Persons A and B are rowing boats due east. B at .5c, and A at .7c, both relative to the earth, and are in parallel tracks 3 light seconds apart (B is north of A). A starts out behind B, but as A passes B, A throws a stopwatch straight up at .5c in A's reference frame. B...

Hello everybody Here is a wicked math riddle. Go ahead and see if you can solve it A commuter is in the habit of arriving at his suburban station each evening at exactly five o’clock. His wife always meets the train and drives him home. One day he takes an earlier train and...

I am trying to find video of a Stern Gerlach experiment under way, does anyone know of a website that would have something like this available?

Our math program requires only three math courses per semester so I can elect to take less intesive courses like music or french but our physics program requires four to five physics and math courses per semester. Because of this, I thought of taking three courses per semester and stay a bit...

I am looking for the derivation to an approximation formula for the differential cross section for hard sphere scattering in the limit of high energy. The paper that mentioned this had referred to Methods of Theoretical Physics, PM Morse and H. Feshbach page 1484 but I have no access to the...

An airplane was carrying 80 bricks. One fell off from the plane. How many bricks will be there in the plane?

It started out OK, like a lot of books, but all of a sudden I hit a mass of integrals at page 22 out of nowhere. No build up, no explanation, many solution steps skipped (of course). Sorry to sound weak, but I need to be "nannied" through the maths of General relativity. I'm a right brain...

So I am taking Physics II this fall semester. I am an engineering major, and I am currently split between mechanical, and civil. My questions is how hard will the class be for me? I have already done the three semesters of calculus including a vector calculus extension. I got an A in calc III...

I've looked up for how REUs are and most of them have a work lapse between May-August or June-August (my semester ends up to July), also lots of them have finance only for U.S. citizens. I can still do research job in my university and I don't want to lose any semester, but I guess it would put...

Hi guys! First post :) I`m a 3rd year high school student. Going to college in 2 years. I am planning to study mechanical engineering. How hard is it? I am not very good in math but I really really really want to be a mechanical engineer. Should i still take mechanical engineering even if i`m...

Over the years I've heard gruesome stories about engineering/science/tech interviews - questions that they expect you to get on the spot (or nearly so) but which would require me to spend a good day thinking. I've already read Poundstone's books but I have to say there are very few good ones...

I have hard time understanding "Such That" {x\inZ|x=2m+1, m\inZ} Is this saying that x is apart of all integers and because of that x=2m+1 where m is all so apart of all integers. if not Is the first part x\inZ because of the second part x=2m+1, m\inZ or Is second part...

Homework Statement Find the average value of the function f(x,y,z)=xyz on the unit sphere in the first octant Homework Equations I know that I need the surface integral of xyz over the sphere and then need to divide by the surface area of the region, but I'm having a hard time setting...

hi guys! can you please help me with this integral? I've tried some subs but i really don't know how to start... Thank you !

I'm going to university next year and I'm strongly considering doing physics. however the I'm slightly concerned because the physics degree at the uni I am going to has very little of the math that i thought is needed for physics. to illustrate my point, in the course there are no PDEs, diff...

I have read several posts asserting that mutation and natural selection cannot add complexity or useful functions to the genome. I'd like to add a link to an experiment that proves them wrong, and also teaches us a lot about how evolution works - the E-coli long term evolution experiment...

Homework Statement A uniform solid cube, of edge 1m and weight 200N, rests on a rough horizontal plane. A light rod AB of length 1.2m is smoothly hinged at A to a point of the plane and B is in contact with a smooth face of the cube. The rod lies in a vertical plane perpendicular to...

I use RTV silicone rubber to make moulds for hard candy. Hard candy is basically boiled sugar that is poured into moulds at just under 300 degrees F. The castings of hard candy develop bubbles on the surface because the silicone does not dissipate the heat, unlike traditional metal moulds...

1. The problem, the whole problem, and nothing but the problem \int \frac{dx}{ \sqrt{ 1+ \sqrt{ 1+ \sqrt{ x } } } } Homework Equations u-substitution (in the style of trig substitution) I think that I've got it figured out, I just don't know if my substitutions were legitimate...

I'm a Junior, about to be a Senior, majoring in Physics at a California State University. I am terrified about my career prospects. I am a fairly good student (3.5 GPA) and really love physics. I've taken Quantum I, Modern Physics, Thermodynamics and a couple E&M classes and I have enjoyed...

A light-weight "pop-up" tent consists of six flexible plastic struts that are inserted into pockets sewn into the joins of the fabric panels. The resulting shape has hexagonal horizontal cross-sections, while vertical cross-sections through the centre are semi-circular. Derive a formula for...

Homework Statement I've been working on this problem for about 2 hours now and I can not get the right critical values. Please help.Homework Equations I found the derivative of the equation is sqrt(3/2) x-3/8 (10-3 x) and I've checked this over many times so I am pretty confident in my...

Hi everyone, I'm reading some lecture notes on statistical physics and thermodynamics and I'm stuck at an expression for a partition function which I really don't understand. The chapter is on mean field theory and the discussion is about hard spheres on a lattice. The interaction of the hard...

http://imageshack.us/photo/my-images/585/circuitzzz.png/ i thought maybe i should ignore everything that is on the right side of the 3v and just focus on the left side. but this one is not looking too good for me. any ideas on this one??

I have a PDE and I have to transform it into an easier one using a substitution: u_t=u_{xx}-\beta u I am supposed to use the following substitution: u(x,t)=e^{-\beta t}w(x,t) I am supposed to get something that looks like this: w_t=w_{xx} Can someone show me the steps?

Find the length of the curve y = x^2 − ln(x), 1 ≤ x ≤ 2. I have have to find the arc-length of the given equation. I have checked my work several times and i ultimately come up with the integral of ((4x^4 -3x^2 +1)/(x^2))^(1/2), which I just cannot seem to solve. Any help would be appreciated.

Homework Statement Find the length of the curve: \phi(t)=\left\{(5+\cos(3t))\cos(t), (5+\cos(3t))\sin(t) \right\}\mbox{ with } t\in [0, 2\pi] Homework Equations L_{\phi}= \int_{a}^{b}\sqrt{[x'(t)]^2+ [y'(t)]^2}\qquad (1.1) Where x(t)= (5+\cos(3t))\cos(t) y(t)=...

When I'm typing latex math (with frequent bras and kets) in the quantum forum, I often put this first: \def\<\rangle \def\>\langle because this is annoyingly ugly: ##<\psi | \phi>,~## but this: ##\langle\psi | \phi\rangle## is a pain to type and edit if there's a lot of it. (There's...

Homework Statement I am trying to directly calculate the electric field (using Coulomb) at some arbitrary point P(0,0,z). The charge is evenly distributed over the surface of a sphere (radius R, charge density σ). Here I use θ for the polar angle and p for the azimuthal angle. I will leave...

Why is there a difficulty in the world to discover new energy sources? That is long lasting, eco-friendly, and highly efficient. We've progressed in many many fields but I find this field being the least... I've been thinking a lot about this, since in the future I'm specializing in this...

Homework Statement Two square plates of sides L are placed parallel to each other with separation d as suggested in the Figure. You may assume d is much less than L. The plates carry uniformly distributed static charges +Q naught and -Q naught. A block of metal has width L, length L, and...

Homework Statement ([3√(x^2+4)^4]^2 Homework Equations None needed. Chain rule product rule etc The Attempt at a Solution I stopped at: [((x^2+4)^4)^1/3]^2 So I have 3 exponents. I don't know how to simplify this in order to move on to do the chain rule or whatever rule...

Homework Statement In how many ways can the three letters from the word " GREEN " be arranged in a row if atleast one of the letters is "E" Homework Equations Permutations Formula The Attempt at a Solution The total arrangements without restriction: 5P3/2! = \frac{5!}{2! * 2!} The number...

I'm new to forums and after I typed all this out and tried to submit, it cleared everything. I really need to get this problem finished tonight. Homework Statement You have two charges (q1 = -15uC and q2 = 3uC) separated by a distance (d = 3m). We want to calculate the electric field, E...

Having a very hard time in my PRECALC CLASS. When they facto problems they start pulling numbers out of numbers that aren't there.. Example.. 3(4x+5)^2 (4)(5x+1)^2 + (4x+5)^3 (2) (5x+1)(5) Professor said this was the answer. a) 2(4x+5)^2(5x+1)[6(5x+1)+5(4x+5)] = b)...

Homework Statement Homework Equations Shell method The Attempt at a Solution Not sure if this is right, but the integral I set up is: 2\pi \int_0^1 (4-y)(\sqrt{siny})dy Finding the radius is my big problem with these problems, I can't visualize it very well. Any help is...

How hard is that SF? – Pharyngula mentions a survey that someone once did, asking people to rate various science-fiction movies on two dimensions. Hard: a work "takes great care in accurately presenting then-known scientific facts". Soft: a work "often and casually violates our understanding...