Exercise Definition and 543 Threads

Homework Statement What is the intensity of the force F_{g} between the ring and a mass 'm', which is at a distance 'x' from the center of the ring? http://img52.imageshack.us/img52/6859/ringre.th.jpg Uploaded with ImageShack.us The Attempt at a Solution I have got to my own...

I try to determine the speed of muons. In an book I have there's an exercise regarding muons. Given that they half of them decay in 2.2 * 10^{-6} s, how fast do they have to travel if half of them is to reach earth, ocean floor? I tried to calculate the speed but I get to a point where I...

Homework Statement Prove each statement using the epsilon delta definition of limit. lim (x^2-1)=3 x -> -2 Homework Equations The Attempt at a Solution Given E > 0, we need D > 0 such that if |x-(-2)|<D then |(x^2-4|<E. If |x+2|<1, then -1<x+2<1 -5<x-2<-3...

A beam of neutrons with energy E runs horizontally into a crystal. The crystal transmits half the neutrons and deflects the other half vertically upwards. After climbing to height H these neutrons are deflected through 90 degrees onto a horizontal path parallel to the originally transmitted...

Homework Statement Write the quantity using sums and differences of simpler logarithmic expressions. Express the answer so that logarithms of products, quotients, and powers do not appear. log_{10}\frac{3}{\sqrt{1+x}} Homework Equations The Attempt at a Solution The...

Homework Statement 2^{5x}=3^x(5^{x+3}) Homework Equations The Attempt at a Solution ln2^{5x}=ln3^x(ln5^{x+3}) 5xln2=xln3(x+3)ln5 Here's where I get stuck... I've tried a bunch of different manipulation, but can't seem to isolate x... Thanks in advance!

Homework Statement We have a thin film of glass which has thickness t=\lambda and n=1.5 and light (\lambda) passing through it with an angle \theta_0. We have to find the minimum angle that allows us to see both constructive and destructive interference. Homework Equations Max...

Need help on this problem: 10. A fireman is holding a hosepipe so that water leaves the pipe horizontally. The hosepipe has a constant cross-sectional area. The magnitude of the force that the fireman exerts to hold the hosepipe stationary is F. The volume of water delivered by the hose per...

Suppose you have the FFT of a sinusoidal signal sampled at 100 kHz and it has energy peaks at k = 100 and k = 412. How many points is the FFT? What is the frequency of the signal?

Hi, I'm searching for hard exercise books, like Mir Moscow publisher books. I've already know Irodov and Mechtcherski. Anyone know about another one as hard as those or harder ? Thanks.

If it's not one thing, it's another... continued... http://news.yahoo.com/s/usnews/20110506/ts_usnews/healthbuzzcoffeesexincreaseaneurysmrisk

Homework Statement a) What is the mass of one mole of Ca(NO3)2? b) How many Ca2+ ions are there in 0.05 moles of Ca(NO3)2? c) How many moles ofNaCl are there in 450 g of this substance? (Avogadro’s number is 6.022*1023 1/mol.) Homework Equations The Attempt at a Solution a)...

Homework Statement In a certain experiment, the power (P) radiated by a light bulb filament was measured as a function of the filament's absolute temperature (T). Data: P(W) 0.45 0.95 1.8 3.5 5.6 T(K) 1000 1200 1500 1800 2000 (a) Plot the data (Done) (b) Assume a power...

Homework Statement Hi, I have to solve this exercise: "Given that (a+bi)^2 = 3+4i obrain a pair of simultaneous equations involving a and b. Hende find the two square roots of 3+4i. Hence find the two suqre roots of 3+4i." I don't really know to do do it. 2. The attempt at a solution...

In aortic stenosis there is ventricular hypertrophy and this could lead to reduced cardiac ooutput. My question is why is the ventricular hypertrophy in aortic stenosis, inferior to ventricular hypertrophy you get in exercise. Why is their better ventricular hypertrophy that increases cardiac...

If A 2x2, show that A^-1 = A^T if and only if : http://www.mathhelpforum.com/math-help/attachments/f5/20406d1294835445-exercise-application-markov-chains-untitled.png [Hint: If a^2+b^2=1, then a=cosθ, b= sinθ for some θ. Use cos(θ-)=cosθcosϕ+sinθsinϕ]

Homework Statement Hi there, I'm starting with rigid body, and I'm having some trouble with it, so I'll need your help :D I have this exercise now, but I will probably come with some others later. The exercise says: The collars A and C glide along the vertical rods and B of the horizontal. If...

The Incredible Flying Nonagenarian http://www.nytimes.com/2010/11/28/magazine/28athletes-t.html Exercise (and diet) is important to good health, especially later in life.

Homework Statement Let's say I have a non invertible system of linear equations: Ax=b Then the pseudoinverse gives a approximate solution: x'=A^+*b (1) Given the property: A*A^+*A = A, prove that x' is a vector which lies in the image of A and minimises the error = ||b-Ax'|| (2) show...

In the current long thread discussing string theory, https://www.physicsforums.com/showthread.php?p=2982921": I replied So here is the promised thread. As I said, I think it's unlikely that this number from the 11-dimensional theory would show up so directly in 4 dimensions. But it would be...

First, I appologise if this is in the wrong place, while the book is QM, the question is pure maths. Also I'm not sure if this techically counts as homework as I am self studying. Finally, sorry for the poor formatting, I'm not that good with LaTeX Homework Statement Given the matrix...

Homework Statement [PLAIN]http://d.imagehost.org/0018/enunciado.png It's in portuguese but what it's being asked is to find the Rth and Vth, the Thevenin equivalents for that network, in that cut point... V2 and all resistors values are known. Homework Equations The Attempt at a Solution...

I'm reading the first chapters of "A Guide to Distribution Theory and Fourier Transforms". On page 10, Exercises 3,6,7 the distribution is defined in terms of integrals. The first one is always without integrand (there's only the integral sign). What does that mean? Am I missing something? The...

Homework Statement The three identical boxes shown in the figure remain at rest on a rough, horizontal surface, even though they are acted on by two different forces, F1 and F2. All of the forces labeled F1 have the same magnitude; all of the forces labeled F2are identical to one another...

Hi everyone, I'm studying an exercise and I got stuck. Indeed, I was asked to prove that: E((1+sqrt(3))(2n+1))=(1+sqrt(3))(2n+1)-(sqrt(3)-1)(2n+1) and I admit I haven't got a clue how to do it. Any indication is welcome!

Hi all, I'm having trouble solving problem 3 at page 105 in Weinberg's book, The Quantum Theory of Fields, Vol. 1: Derive the commutation relations for the generators of the Galilean group directly from the group multiplication law (without using our results for the Lorentz group). Include the...

Homework Statement Find the equation of a tangent line to the curve y = x³ - 1, that is perpendicular to y = -x (I mean the tangent line should be perpendicular to y=-x, sorry for my bad english). Homework Equations The Attempt at a Solution y = x^3 - 1; \;\; y' = 3x^2 If the tangent line...

Basic exercise for finding a Lagrangian from the Landau's "Mechanics" Hello everyone! Homework Statement I've just started preparing for the classical mechanics course using only Landau & Lifgarbagez, so I'm doing everything according to their formulation. And so I solved an exercise...

2Arctan(1/3) + arctan(1/7) = π/4 I try to solve it like this: = sin(2arctan(1/3)) + sin(arctan(1/7) = sin(π/4) But this isn't correct What have I done wrong?

Homework Statement Suppose k>2, x, y in R^k, |x-y| = d > 0, and r > 0. Prove if 2r > d, there are infinitely many z in R^k such that |z-x| = |z-y| = r (In Principles of Mathematical Analysis, it is problem 16(a) on page 23.) Homework Equations |ax| = |a||x| |x-z| < or = |x-y| + |y-z|...

Homework Statement Hi guys, I am new to this forum. I got a final exam tomorrow and the professor told us to solve some exercise before it. I came up with one exercise that I don't know how to do, at all. Hope you guys can give me some light. Here it goes. Know that the multiplication of...

Homework Statement Let there be 3 particles with mass m moving in the 1D potential: \frac{k}{2}[(x_1-x_2)^2 + (x_2-x_3)^2 + (x_1-x_3)^2] where x_i is the coordinate of the particle i. 1)Show that with the following coordinat change the Schroedinger equation is easy to solve: y_1=x_1-x_2...

Hello... I have a question about the solvable group. I read a Fraleigh's 'A first course in abstract algebra', there is a question in sec56, exercise3. It says "The Galois group of a finite extension of a finite field is solvable." is true... I can't figure out why it's true. I think this...

Homework Statement A friend of mine tried to classify for the IMO a few days ago (he didn't do so well). A problem he had to solve was: f(x + xy + f(y)) = (f(x) + 1/2)(f(x) + 1/2) I didn't really understand what he said later. First he told me to find the values of X and Y for which...

So this is supposed be an introductory problem for tensor products that I was trying to do to verify I am understanding tensor products...turns out I'm not so much Show that M_n(K) is isomorphic as an F-algebra to K \otimes_F M_n(F) where F is a field and K is an extension field of F and...

Homework Statement Avril has certain standards for selecting her future husband. She has n suitors and knows how to compare any two and rank them. She decides to date one suitor at a time randomly. When she knows a suitor well enough, she can marry or reject him. If she marries the suitor, she...

One way muscle grows is muscle hypertrophy where sarcoplasmic fluid increases inside the muscle cell. Wouldn't this burst the cell membrane, I can understand how organelles can replicate but what about the cell membrane. I know this sounds like a stupid question but please help. Thanks :smile:

Hello, I am a student of electrical engineering of Madrid (Spain).. And I need to present a simple but original exercise with the program Femm. I have done a workshop of 10 hours and more or less I control the basic thing, have done some exercise as bobbins, condensers, etc... I was...

Hi all, I posted this awhile back in the homework sections of the forums and received only one reply, which suggested that I post it here instead, though I understand that it belongs in the homework section. The fundamental problem is not this particular exercise but about integration of...

Homework Statement The problem I am facing is 2.9 in Sean Carroll's book on general relativity (Geometry and Spacetime) I should note that I am not studying this formally and so a full solution would not be unwelcome, though I understand that forum policy understandably prohibits it. The...

Homework Statement This was a problem I needed help on. A train is traveling up a 3.73 degree incline at a speed of 3.25 m/s when the last car breaks free and begins to coast without friction. a). how long does it take for the last car to come to rest momentarily? b). how far did the...

Firstly, I've literally never used a Linux machine in my life. My phys prof thought it would be a good idea to get us acquainted with the system, but didn't want to actually teach it... The following is an exercise in Linux. I'm having a lot of trouble finding the commands to accomplish this...

http://online.wsj.com/article/SB10001424052748704350304574638331243027174.html Doesn't sound like vigorous exercise to me at all. How on Earth can biking at a speed of 10 miles an hour be vigorous exercise? :confused:

Homework Statement Note that am a beginner in physics,hardy know any,so be gentle (: There are three particles in a line below. The question is where must we put Q3 so it will get 0 total power. Q1=6 mC Q2=15 mC Q3= -8 mC In a line of 2 meters like this...

Homework Statement A 75kg person is put on an exercise program by a physical therapist, the goal being to burn up to 500 food calories in each daily session. Human muscles are about 20% efficient in converting energy into mechanical energy. The exercise program consists of a set of consecutive...

If a crew member were stranded on space station, due to spin, would he be rescuable? For example if an extended part bent or broke, putting the ship into a spin or tumble. If it were a one axis spin, perhaps a large mass, attached at a distance would change moment of inertia sufficient to...

Homework Statement A small conducting spherical Shell (#1) with inner radius a and outter radius b is concentric with a larger conducting spherical shell (#2) with inner radius C and outter radius d. The inner shell has a total charge (-3Q), and outter shell has a charge ( +5 Q). a) Use...

So I am in a quantum course and as a reference text we have cohen's quantums mechanics volume 2. I've been using it to practice and study for the midterm, I've been doing the exercises but not sure if I'm doing them right, does anyone know if there are solutions to the exercises in this book...

Homework Statement Problem 2, chapter 3 of Wald's General Relativity. The details don't matter much, but it is given a totally anti-symetric tensor field Eab such that EabEab=2(-1)^(s), s being the signature of the metric. I have checked a solution to the exercise, and somewhere during the...

Homework Statement An electron moves in a helix : \vec{r}(t)=v_{z}t \hat{z}+a e^{i\omega_{0}t}(\hat{x}-i\hat{y}), where a is the radius of the helix and v_{z} the relativistic z-component of the velocity. 1) Find the position vector of the electron in a system of reference that is moving...