Hard Definition and 1000 Threads

I have been trying to solve the problem in part (vi) for almost a whole week, but still not able to solve it. Please read the attachment before proceeding. I was able to show that, using part (iii), we can construct a deterministic program S from P. Then S gives the same outcome as G for the...

Ok, so to form the factor groups, let's say G(+)H/J, you take every element of G(+)H and left multiply by elements of J. Well elements of G(+)H look like (g, h) and elements of J look like (g, e_2)...so elements of the factor group look like (g_i, h_i)(g_n, e_2) = (g_i*g_n, h_i) Am I...

What material is suitable in windows for hard X-rays? What material would you choose as reflective coating of X-rays mirrors for radiation at 200 eV? Why?

Hi there, does anyone knows the overall dimension for 2.5' hard disk drive?including all the components inside. who has the complete dimension? tq =)

Hi everone, i am trying to Solve the N.-St.-equation for a special problem - i was able to solve my equation for the 2 velocity components - the 3rd velocity component i seperetated - one term of the Seperation i was able to solve with a Bessel function, the 2nd term now looks like this...

Homework Statement Plane α: x-2y+z=2. Plane β: 2x+y+z=5 Point P= (0,1,4) is on the line of intersection, with directional vector L, between the two planes. A sphere is touching plane alpha at point A and plane beta at point B. Show that PB is perpendicular to L and the normal vector of...

Homework Statement http://img694.imageshack.us/img694/1115/pendulumcutquestion.jpg Please ignore the blue pen. Homework Equations Ek=1/2 mv2 Ep=mgh The Attempt at a Solution Basically I looked at the problem firstly as the pendulum has reached the lowest point, therefore...

why would a hard boiled egg spin and raw egg won't if made to spin on a flat surface?

Homework Statement Calculate the numerical value of the energy difference between the 2P 3/2and the 2P 1/2 states in Hydrogen (the fine structure). Homework Equations possible relevant equations are in the attachement The Attempt at a Solution It is quite unclear weather the...

Alright, well I am having a difficult time getting these equations to equal out! I keep hitting trouble and have hit a road block. Here is the problem... csc(x)+cot(x) = cot(x)csc(x) tan(x)+sin(x) I am just going to work on the LEFT PART of the equation. 1 + cos(x) sin(x)...

Homework Statement ∫dz/(z4+1) integrated over the curve C1(1+i) Homework Equations The only thing we learned in this chapter is Cauchy's integral formula, so I'm assuming that comes in somehow. The Attempt at a Solution ∫dz/(z4+1) = ∫dz/(z+1+i)(z+1-i)(z-1+i)(z-1-i) Not bad...

Homework Statement As said in the title, why is the thick disc of our galaxy hard to study? The attempt at a solution I thought at first it may have something to do with the fact that the thin disc is so populated with stars that the light coming from it may interfere when trying to...

Hi everyone, I have been trying to do this induction question... but can't seem to understand how to do it. Prove by induction that, for all integers n is greater than or equal to 1, (n+1)(n+2)...(2n-1)2n = 2^n[1x3x...x(2n-1)] This is what someone else has given as the answer: For n...

For you who have actually worked with it..., More unknowns than equations? Self-referential? ?

Hey, long time no see! :-D Well the subject line pretty much says it all. When I plug in my Simple Save external HD it does turn on, and my computer does recognize it. But when I try to open it I get an error message "F:\ is not accessible. Access is denied." Also, when I plug it in Windows...

Homework Statement Solve \int^{\infty}_0\frac{\sin x}{\sqrt{x}} Homework Equations The Attempt at a Solution \lim_{t\to \infty}\int^{t}_0\frac{\sin x}{\sqrt{x}} \sqrt{x}=v so \lim_{t\to \infty}\int^{t}_0\frac{\sin v^2}{v} Integration by parts maybe? What is idea?

I still can't even start a problem after hours of studying the subject. I feel like an idiot, or that I'm just trying to do something that I can't do. The book that we use, nothing helps in it to solve the problems. All they give is the basic form of the equations. Doesn't tell you...

Equivalent capacitance... A hard one!? Homework Statement Calculate Equivalent capacitance between A and B: [PLAIN]http://scsupport.org/moodle/file.php/13/Chapter26/imgch26q14.gif EDIT: If you can't see the picture, see 3rd post for file attachment, sorry!Homework Equations C1 = 3.55 µF C2 =...

Homework Statement the question asks to determine if the equilibrium is greater, equal or less than 1. one of the equation is the following: [CuI4]2- (aq) + [CuCl4]3- (aq) ↔ [CuCl4]2-(aq) + [CuI4]3- (aq) Homework Equations The Attempt at a Solution the solution given was...

Can someone dummify what theta represents in Torque = rFsin(theta)? if my understanding of theta is correct for this problem theta would be 53 degrees. (See attached picture)

I'm a sophomore math major, and I' currently taking proofs, linear algebra (not proofs-based), and calc 3. These classes aren't that bad so far. I met with a math adviser today, and he told me for my major requirements I should take real analysis 1&2, Linear algebra, and abstract algebra for a...

Homework Statement Using that the Fourier transform of e^{|x|} is \frac{2}{\xi^2+1}. Compute the Fourier transform of \frac{x}{(x^2+1)^2}Homework Equations The Attempt at a Solution My first thought was to try and rewrite the problem in a form I recognized, tried a couple of things but what I...

Homework Statement Potential energy function A particle of mass m, starting from x = −∞, approaches a force region whose potential is given by V (x) =(ka^2)/((x^2)+(a^2)) where V0 > 0 and a are constants. (a) Derive an expression for the force on the particle as a function of Homework...

Hi, so I'm trying to troubleshoot my gf's external hard drive and I'm looking for some advice or suggestions on things to try. Basic specs: Age: 1 -2 years Capacity: 500gb Interface: USB 2.0 Brand: Western Digital She was just transferring files to it and suddenly it became super...

A helicopter at rest on the ground started to accelerate uniformely upwards. After 30s a flare was fired horizontly from the helicopter. An observer on the ground measured the time the flare reached the ground as 10 seconds. Neglect air resistance. A) acceleration of helicopter B) height...

Homework Statement Sphere with P as centre has equation (x-5)^2 + (y-9)^2 + z^2 -100 = 0 Sphere with Q as centre has equation (x-1)^2 + (y+3)^2 + (z-3)^2 -49 =0 These spheres intervine with each other. Find the surface area of the object limited by the two spheres. The Attempt at a Solution...

I'd like the very intelligent people populating this forum to work with me on specific aspects of the problems of consciousness and life in an attempt to gain some consensus on key issues - at least in this forum. My hope is that with some better organization of thoughts and responses than has...

Hello, could someone point out to me 1) Ironclad evidence of correlated light curves - and I mean a correlation that is beyond doubt - among lensed quasars 2) Morphological correspondence - e.g. corresponding jets - in images of lensed quasars. I can find sketchy cases which may be...

Homework Statement Let f be the 2pi periodic function defined by f(x)=e^{cos(x^{2})} for 0 < x < 2pi. What is the value of the Fourier series at x=4pi Homework Equations The Attempt at a Solution I don't even know where to start. All help is much appreciated!

Homework Statement Suppose the hard disk above has 1024 cylinders, 8 tracks per cylinder, 32 sectors per track and 512 Bytes per sector. The maximum seek time is 450 msec, the time to move between adjacent cylinders is 10 msec, the rotation time is 14. a) If the entire disk was full of...

What do you do when that happens? You're fully motivated to study what you have to, then it turns out that you just can't seem to grasp certain concepts. Either it's because you're tired. Or you simply can't *see* it right and you just don't get what's going on and it makes you miserable. What...

The brakes on your automobile are capable of creating acceleration of 14 ft/s2. If you are going 82 mi/hr and sud- denly see a state trooper, what is the minimum time required to get your car to 55 mi/hr? How far do you travel while returning to the legal speed limit?

Homework Statement Prove that if p is a prime and a, b \in \mathbf{Z} with a \not \cong 0 \mod p, then ax \cong b \mod p has a unique solution modulo p. I'm having a hard time proving there exists only one solution by using a contradiction. But my biggest problem is that I don't understand...

Hello Physics Forums! I am new to this forum but have definitely been browsing through here for a while now. I am just wondering how hard is it to get an A in physics? I am talking about the beginning general physics with calculus. From what I have seen, students at my school seem to have a...

Dear All, I am figuring out the initial velocity of a projectile in order to do a estimation. I have a horizontal force of F pushing a projectile horizontally (meaning a horizontal launch) from a height H. I assume there is no more force pushing it afterwards. I want to know how far...

Hi! I'm a new undergraduate physics student from Mexico, I study in UNAM. The reason why I posted this here is because of desperately needed advice and support. My first two weeks of school have been pretty hard and I cannot grasp most of the things we're being taught. For example...

Response to Deleted Thread that I've Worked on Too Hard to Let Go! This is one of my responses to the "Cold Air" thread under the "Earth" category. The thread was deleted, but there was one really excellent response, to which I counter-responded, except that the thread was deleted before I...

Homework Statement A sample of hard water contains 305 ppm of HCO3- ions. What is the minimum mass of CaO required to remove HCO3- completely from 1 kg of water sample? Homework Equations Ca 2+ + 2HCO3 + CaO = 2CaCO3 + H2O The Attempt at a Solution Since the HCO3- ions are...

Actually, I understand the basics of how hard drives work, my question is more specific. I'm curious as to how a computer's hard drive can simultaneously delete files, read files, and download files all to/from different places on the hard drive. It can't just be due to a fast-moving head, it...

Homework Statement Find the arc length of the following curves on the given interval by integrating with respect to x y=x^4/4+ 1/(8x^2); [1,2] Homework Equations Let f have a continuous first derivative on the interval [a,b]. The length of the curve from (a,f(a)) to (b,f(b)) is...

Is it needed to be a genius to do difficult intelectual work? Is every theoretical scientist that does important work a genius? This is bugging me lately. Sometimes I'm going to do some things but I think "If you do this right you can be considered a genius or atleast a very intelligent...

Hi, I'm currently self studying "Principles of Quantum Mechanics" by R. Shankar. (Its prep for research, a Prof. recommended the book.) I have only done 2nd year of intro to QM which only covers 1st few chapters of griffiths. (Know multical) I find myself having a hard time going to...

Does anyone have any experience with replacing a laptops hard drive with a solid state drive? I want to buy a cheap little laptop, an Acer, but also buy a solid state drive and immediately swap out the mechanical drive for a solid state drive. Does anyone know if this is typically possible...

Homework Statement Evaluate integral sin^(-3/2)(x)cos^3(x) dx Homework Equations tan(x)=sin(x)/cos(x) sin^2(x)+cos^2(x)=1 sin^2(x)=(1-cos(x))/2 cos^2(x)=(1+cos(2x))/2 integral cos(x)dx = sin(x) + c integral sin(x)dx = -cos(x) + c d/dx sin(x) = cos(x) d/dx cos(x) = -sin(x) a^m/a^n=a^(m-n)...

Here is an interesting opinion piece from the WSJ that talks about President Obama's lack of heart when it comes to governance. While I obviously have no love for the man's policies and mindset, I think it brings up a greater question: Do you elect an official to respond to the public's every...

Homework Statement A construction company has been offered a contract for $7.8 million to construct and operate a trucking route for five years to transport ore from a mine site to a smelter. The smelter is located on a major highway, and the mine is 3 km into a heavily forested area off...

Homework Statement One interesting property of a Fibonacci sequence is that the ratio of the values of adjacent members of the sequence approach a number called “the golden ratio” or PHI. Create a program that accepts the first two numbers of a Fibonacci sequence as a user input and then...

I've tried to ask this on the physics section but nobody know how to do it a = g(sen\alpha - cos\alpha u) -(\frac{v² u}{R}) V = \sqrt{Vo² + \int 2a.ds} \alpha = \frac{s}{R} Then, find the function v

Homework Statement I need to evaluate the following limit: lim_{n\rightarrow\infty}\left(\frac{1}{n!}\right)^{\frac{1}{3n}} Now, I think I have solved it, but my methods are not rigorous. I am looking to see if my assumptions are sound and if there is an easier way to solve this limit...

a 50 g Hard Boiled egg moves on the end of a spring with force constant k=25N/m. Its intial displacement is .3m. A damping force F=-bv acts on the egg and the amplitude of the motion decreases to .1 m in 5 sec. Calculate the magnitue of the damping contant b. How exactly do you go about doing...