Hard Definition and 1000 Threads

I recently bought 2 - 1 tb external hard drives from tiger direct. http://www.newegg.com/Product/Product.aspx?Item=N82E16822111019 My computer and other computers I have tried them on will not recognize them both plugged in together. it only recognizes the one i plug in first then when i...

The picture speaks for itself, can anyone explain to me how to do this, they put it near the start of my book and i keep coming back to it yet no sine or cosine formulae etc... can help, please :)

Homework Statement Let A and B be sets and let f: A \rightarrow B be a function. Define a function h: \mathcal{P} (B) \rightarrow \mathcal{P} (A) by declaring that for Y \in\mathcal{P} (B), h(Y)= \{ x \in A: f(x) \notin Y \}. Show that if f is a bijection then h is a bijection. The...

basically, my opinion is that STEM careers are enjoyable BUT intellectually a lot toughter than other careers. It's been theorized that the reason why less Americans (and more foreigners) major in STEM is because kids who grew up in America do not want to work very hard (a product of...

I am currently a student taking a break from school. Last year I had a major life altering experience and after which i decided to take a break from my studies till my mind was settled. When I started my undergraduate track I went to a tech school in NY and had decided on studying software...

I saw a post on this forum from a few years ago ('07) asking the same question, but I thought it might be good to ask it again: Is anyone here a gay physicist, chemist, etc. in the hard sciences? It'd be nice to have someone to chat with online that's in the same situation, since it is...

Homework Statement In Fig. 13-41, a particle of mass m1 = 0.23 kg is a distance d = 84 cm from one end of a uniform rod with length L = 6.4 m and mass M = 2.4 kg. What is the magnitude of the gravitational force on the particle from the rod?Homework Equations...

I was accepted to an electronic engineering course as a mature but I only put that course on the list for the sake of putting a few courses down. The real course I want to get into is chemistry but I did a bad interview for that course and I got accepted into electronic engineering instead. The...

Greetings, As I am in vacation now there is no way to ask my teacher so I will resort to this forum, I searched and didn't find it on the forum ( hope I haven't skipped anything ) so here goes my question: For the Runge-Kutta integration methods, I am really puzzled as to what the 'f'...

I'm taking the class next semester, and I heard that number theory is usually a difficult subject. Is that true? If so, how should I approach it?

I have a laptop at at the moment but I'm afraid that I chose the wrong one. Its a 16in, 7.1lb monster with a battery life of a measly 2.5hr max. I could upgrade the battery but it would add over a pound in weight and make it even bulkier though. I'm thinking about returning it (if I can) and...

Hello all, I'm new here to the forum. My name is Chris and my one "burning" question is that do you think that being hard of hearing will be a major obstacle for me to pursue in this field for a career? I know that the military still refuse to hire any of us but I'm wondering in the other...

I would like to know how to "defrag" a hard drive, and what the gains are to doing so. I am using windows vista home premium 64-bit with a single hard disk installed into my computer. Where do I go to defrag my drive? How long does this take? Are there any potential risks of causing data damage...

tractive motion, with gradients, Hard questions! 4.1 An engine mass of 95 tonnes is hauling a train of mass 750 tonnes along a section of level track. the tractive resistance to motion of the engine is 120 N/tonne and the rolling resistance for the train is 90 N/tonne. initially the engine is...

Really hard intergration problem\! take a look A 20-lb. monkey is attached to a 50-ft. chain that weighs 0.5 lb. per (linear) foot. The other end of the chain is attached to the 40-ft.-high ceiling of the monkey's cage. Find the amount of work the monkey does in climbing up her chain to...

Hard intergration problem! 1. A 20-lb. monkey is attached to a 50-ft. chain that weighs 0.5 lb. per (linear) foot. The other end of the chain is attached to the 40-ft.-high ceiling of the monkey's cage. Find the amount of work the monkey does in climbing up her chain to the ceiling...

Compound gear train problem (WHY IS IT SO HARD!) Homework Statement http://img5.imageshack.us/img5/1663/problemw.jpg I need to calculate the angular acceleration of the fan at 2600 RPM (motor speed) depicted by figure 4. Homework Equations Sum(torques with respect to input) =...

Homework Statement Two objects are placed in a 1 dimensional box with springs of different constants at each end of the box. The box is made of wood and has a length of L. The first object has a mass of M and is initially compressed a distance of xinitial onto spring 1 of spring constant k...

I posted this on another thread but no one has responded. It is truly a great puzzle to work out. So, I am posting it again in its own thread. Enjoy. The "Hardest Logical Puzzle Ever": Three gods, A, B, and C, are called True, False, and Random (in some order you do not know.) True...

Calculating spring equilibrium length HW question... HARD! Homework Statement A spring is connected to the bottom of a ramp inclined at an angle of 45 degrees. In its equilibrium position, the spring is equal to the length of the ramp, L. If the spring constant is 500 N/m and I want to launch...

I'm going to be doing a little venting in this thread so if you don't want to hear about it, click the back button. I'm in my second year of school right now. I'm in Physics 2 which is just basic calc based physics (second semester). I am in awe at how hard this class is. I'm sure most of...

Homework Statement A hawk flying at 2 m/s at an altitude of 80 m accidentally drops its prey. The parabolic trajectory of the falling prey is described by the equation below until it hits the ground, where y is its height above the ground and x is its horizontal distance traveled in meters...

I need to replace my hard drive. The recommendation is: ATA/100 5400 RPM 9.5mm. I see a lot of faster drive 7200rpm but they are SATA. Is it true I can put this in also because they connector should be compatable. I just need to get 9.5mm or smaller and it would be fine? What is the...

Is chemical engineering ridiculously hard? If i really enjoy chemistry would chem engineering be a good choice?

Or at least... that's how it seems... I'm an Astronomy Major. In the summer, I'm all 'I can't wait to study x y and z!' and then two weeks into the semester, I'm just, 'meh. My homework can burn in hell' Completely unmotivated and don't know my future outlook. I pass my courses with average...

[SIZE="2"]Homework Statement The only force acting on a 2 kg object moving along the x-axis is shown. If the velocity Vx is 2 m/s at t=0, what is the velociity at t=4 s ? Homework Equations P= mv The Attempt at a Solution Area under the curve is the Impulse, which is Pf - Pi and...

Hello All, Well to make the Story short, I made a little bet in school that I could solve all the number sequences on a site, but now's the joke. I can't Ye ye , stop laughing But really I can handle myself at numbers normally pretty well, but this seems out of my league Can anyone solve...

Homework Statement \int_0^1 \frac{x^4(1-x)^4}{1+x^2}\ dx The Attempt at a Solution A gonio substitution gets nasty really fast moreover the differentiation under the integral sign trick doesn't seem to give more insight (at least that's what I think). Integration by parts gets a ln(.) times...

Homework Statement Five dice are rolled. You win a dollar for each number other than a five that is rolled, but you don't win extra for duplicate numbers; for example if [3,5,3,2,1] is the result, then you win three dollars. What should you pay to play this game (what is expected value)...

Homework Statement \int_{0}^{\pi/4} \exp \left(-\frac{1}{\cos^2x}\right)\mbox{d}x The Attempt at a Solution Can someone give me a hint? I don't see a smart substitution nor a path via integration by parts...

Greetings, I am 14 years of age and I am thinking of choosing a profession revolving around neuroscience. My query is how hard is it to enroll in the related university and how much work does it require? -Thanks

I have to choose what I want to do in university and I was wondering how smart you have to be to do theoretical physics. I do maths , applied maths and physics in school and I'm good at all of them. Any help is very much appreciated.

Homework Statement A computer is reading data from a rotating CD-ROM. At a point that is 0.030 m from the center of the disc, the centripetal acceleration is 120 m/s2. What is the centripetal acceleration at a point that is 0.050 m from the center of the disc? Homework Equations ac =...

Two identical blocks are tied together with a string and placed along the same radius of a turntable that is spinning about its center. The inner block is 4 cm from the center and the outer block is 5 cm from the center. The coefficient of static friction between the turntable and the blocks is...

Homework Statement "During workout, the football players at (insert generic college here) ran up the stadium stairs in 66 seconds. The stairs are 140m long and inclined at an angle of 32 degrees. If a typical player has a mass of 95 kg, estimate the average power output on the way up...

Construct an isomorphism A4 (AND) D4 ---> (Z/2,+)X(Z/2,+) where D4's the symmetries of the square so I found D4(And)A4={(13)(24),Id,(12)(34),(14)(23)}

Really hard Volume Question. URGENT! Can someone help me with this question? I don't know where to begin. I don't want the answers, just hints in the right direction *edit* can a mod please fix the topic title? It's supposed to read 'Really hard Volume Question. URGENT!' << Done. >>...

A thick spherical shell of charge Q and uniform volume charge density p is bounded by radii r1 and r2, where r2 > r1. With V = 0 at infinity, find the electric potential V as a function of the distance r from the center of the distribution, considering the regions (a) r > r2, (b) r2 > r > r1...

Homework Statement First z(t) + (-tz + 3t)dt=0 Second: in attachment Homework Equations How can one solve hose integrations I was faced as one part in solving Dif. equation. The Attempt at a Solution I have tried to soleve bouth of them by usin substitution rule but I have failed do...

Homework Statement Let f(x) be defined and differentiable on the entire x-axis. Show that if f(0) = 0 and everywhere |f'(x)| <= |f(x)|, then f(x) = 0 identically. Homework Equations The Attempt at a Solution I didn't really know how to get started, but as I worked through the problem, I...

Homework Statement A person standing at the top of a hemispherical rock of radius R kicks a ball (initially at rest on the top of the rock) to give it horizontal velocity vi (a) What must be its minimum initial speed if the ball is never to hit the rock after it is kicked? (b) With this...

Hello, this question is about symmetry of polar coordinates. For a polar-curve to be symmetric around the x-axis we require that if (r,a) lies on the graph then (r,-a) or (-r,Pi-a) lies on the graph. To be symmetric about the y-axis we require that (-r,-a) or (r,Pi-a) lies on the graph...

1. Homework Statement You are on an island, and you reach a fork in the road. You want to go to the Cuddly-Wuddly tribe, not the Nasty-wasty tribe. Cuddly-Wuddlies always tell the truth, while Nasty-Wasties always lie. A man is standing in the middle of the road, but you don't know what tribe...

Homework Statement Imagine a tank traveling at constant speed v1 along direction AB and a missile is chasing the tank with constant speed v2. The direction of motion of the missile is always pointing toward the tank. At the t the tank is at position F and the missile is at position D, where FD...

Gizmag directed me to a website where the following ad appears. I don't think that quoting it violates copyright, since the owners of it want it to be seen, but the Moderators should probably vet it anyhow. The reason that I'm posting it is because I'm very interested in buying one, but I'm...

Homework Statement An object with a charge of +4.0 x 10^-18 C and a mass of 1.1 x 10^-15 kg is held stationary by balanced gravitational and electric forces midway between horizontal charged plates. What is the applied voltage V? Homework Equations The Attempt at a Solution I...

Hello guys, I am asking this out of complete curiosity, as I am not in the position yet to need to know this information. I was wondering if it is harder to get into a top tier school for graduate or for undergraduate? It seems to me that graduate would make more sense, its higher education so...

Hi PF, What are the major difficulties the man faces when he tries to reach the Moon? Is it because he has to return to Earth, so that the difficulties are more than doubled? Because the distance between the Earth and the Moon is not that big compared to Earth's equator circumference (less...

Recently I've gained interest in reading the classical works of mathematicians and physicists and came to the realization that knowing Latin would be of great use. Is it worth the effort to learn the basics necessary to comprehend for example Gauss' works, or might I just as well get the...

A 46-g golf ball flies off at 1.5 times the velocity of the clubhead that struck it. a) Show that the mass of the clubhead was 138g. b) What proportion of the clubhead's initial kinetic energy was transferred to the ball?