Application Definition and 998 Threads

Homework Statement The speed of light in a medium with index of refraction n is c/n, where c is the speed of light in vacuum. Notice that n ≥1: Suppose a light ray travels in the xy-plane between (x1; y1) and (x2; y2) in a non-uniform material so that n(x) is the refractive index of the...

Hi, I recently bought 10 Zener diodes the last time I purchase circuit elements. I was wondering if anyone had simple circuits or projects I could do, that needs zener diodes.

Homework Statement Provide one self drawn graphic. Topic: artificial heart valve designThe Attempt at a Solution I'm a second year biomedical engineering student and our professor wants us to provide one self drawn graphic for a paper that is due on thursday We take classes in autodesk...

I haven't taken the chemistry GRE exam yet, and I certainty don't plan on doing poorly, but part of me wonders if I did do poorly how if would affect my applications. A majority of the places I am applying to do not require it (but "strongly recommend" it). So if you get in the 50th...

Homework Statement Given 2 functions f(x) and g(x) that are differentiable everywhere on R and f′(x) = g(x) and g′(x) = −f(x). Prove that 1. Between any two consecutive zeros of f(x)=0 there is exactly one zero of g(x)=0, 2. Between any two consecutive zeros of g(x)=0 there is exactly one...

Let T: P2(ℝ) --> P2(ℝ) be defined by T(p(x)) = p( x-1) a) Find the matrix of T with respect to the standard basis of P2(ℝ) Question: So I know how to do this for the most part, I'm just having a problem in terms of the constant 1 from the standard basis of {1, x , x2 from P2(ℝ)...

Hello PF! I've got a lab on rigid body motion tomorrow, and I need help completing one of the prep questions: A rigid body is acted on by a force F through its center of mass, and also experiences a torque caused by a similar force F at radius R. At time t, what are the linear and angular...

Hi all. I have a question about PhD application. I'm from Italy but I'd like to take a PhD abroad. In my country the physics degree is divided in 3 years + 2 years. At the end of the whole 5 years course we get a degree equivalent to a Master degree. My question is: I was looking, for...

Dear Probability subforum, I have hard time thinking through how 11% is calculated. Anyone have any ideas? From "Thinking fast and slow" Kahneman. p 154 "...If you believe 3% of graduate students are enrolled in computer science (the base rate), and you also believe that the description of...

At the moment, I believe the fastest electric car is made by Shelby Super Cars and it can go at a top speed of 208 mph. Are there any estimates around predicting how fast electric cars will be once companies start using superconductive motors?

Homework Statement This is actually just a problem that I'm trying to work out on my own (working on a little project). The ultimate goal is that I'll know the amount of liquid coming out of the spigot per second, so I'll know roughly how long to open the spigot for to fill up a container...

I am trying to make a program that locks a computer unless you have a password by systematically looping through and closing applications. It would also have a list of applications that the user is ok with having open, (for example a dock like rocket dock or a desktop tool like konfabulator or...

I know that for a system of particles, the x, y and z coordinates of the centre of mass are given by (\frac{1}{M} \sum_{i = 1}^{n} m_i x_i, \frac{1}{M} \sum_{i = 1}^{n} m_i y_i,\frac{1}{M} \sum_{i = 1}^{n} m_i z_i). For a solid body, we can treat this like a continuous distribution of matter...

In several recent threads the Poynting's theorem was brought up, and the discussion there became a distraction from the questions at hand without really being solved: https://www.physicsforums.com/showthread.php?t=621018 (starting #74) https://www.physicsforums.com/showthread.php?t=628896 (this...

Homework Statement There are two boxes: - in the first one there is 1 red ball, - in the second one there are 2 balls, 1 red & 1 white. 1st draw: We take a ball from the second box without taking a look at the color and we put it in the first box. 2nd draw: We take a ball from the...

I will show you my (obviously wrong) way of thinking when i have to apply an integral. Please correct me where I'm wrong. (imaginary question) Suppose you have a mass distribution across a line, where the mass of each point is given by the equation f(x)=a*x (assume a is a constant) find...

Hi everyone I have a quick question regarding heat transfer. I have yet to study heat transfer yet but I have a basic understanding of the mechanisms from general physics courses. My particular question is regarding airflow across a surface and its ability to cool a heat source. The situation...

I'm applying to Cambridge Maths. Will I be disadvantaged if I only take 3 A levels and no additional AS? I have no GCSE equivalent as well.

Homework Statement Find the value of the line integral \int C(e-x^3 - 3y)dx + (tan y + y4 + x) dy where C is the counterclockwise-oriented circle of radius 4 centered at (0,2). The Attempt at a Solution First off, I didn't think this was path independent since the derivative of the dx term...

Hello everybody, I will be graduating with an undergraduate degree in physics this year. I am not an American and I would like to go to graduate school in the US. Last semester I failed some upper level classes and because of some personal stuff and my GPA is lower than 3 now. I want to...

Homework Statement Let f(x,y) = xe^{x^2 + y^2} + y^3 + cos x a) Show there exists a differentiable function \phi(y) such that x = \phi(y) solves f(x,y) = 1 in some neighborhood of (0,0) in R^2. (Meaning (x,y) satisfies f(x,y) = 1 for (x,y) near (0,0) if and only if x = \phi(y)) Prove your...

how is the wavefunction of 1-D infinite well modified by the application of an electric field to the well.

My name is Andrew Bentley, a Geology student of Temple University. I am currently working on a thesis that uses a geostatistical technique that uses semivariograms on ground-penetrating radar (GPR) data. I would have posted this in the Earth Science section but all my issues are in the...

This device was sitting outside my work area 2 weeks ago. I am enjoying working on devices which are at the forefront of oceanographic research.

Hi everyone! I'm trying to work out a physics problem using Lenz's Law, but I'm having trouble with the Right Hand rule, which as I understand is supposed to be used to solve the problem. 1. Basically, there are 2 copper wire loops, Loop A and Loop B. They are lying flat on the table. There...

Hello, I have to give a presentation on an application of electromagnetic field theory of my choosing, and I was wondering if anyone had any suggestions that might be more interesting than the ones that have been suggested. It's for a 2nd year university level physics (E&M) course, so the...

Hi everyone, I do economics but am very poor at Math. I had a specific and perhaps silly question about the implicit function theorem, but will be grateful for an urgent response. Suppose we have a function, U(x, y). x and another variable z are linearly related so the function can also...

Homework Statement Use the shell method to find the volume of the solid obtained by rotating the region bounded by y=x2, y=0 and x=1 about the x-axis. Homework Equations lim Ʃ2∏RhΔw Δw->0 The Attempt at a Solution I realize this is hard to visualize without a graph. I...

I have an idea in which I need to manipulate a positron using an electrical field. However, in order for the problem to work, I need to make sure that the positron's kinetic energy is under 511 keV. to do this, I used Coulomb's law (F=\frac{kQ1Q2}{r^2}) to obtain the force. Because F = ma, I...

I am looking a definition and application of Radii of Gyration. I want to understand this concept by looking at a 50x100 Tube withstanding wind pressure as I have drawn using Autocad. So far I do know that the greater the Radii of Gyration, the greater the rigidity of the section i.e the...

It is not from my howework(due I'm not in the undergrad now), but it seems to be a very easy question I have to know answer to, but I fail to do so. Homework Statement I have to go from classical to quantum Hamiltonian via WKB method (and both to solve Schroedinger equation) It looks...

Investigate the possibility of solving x2-4x+2y2-yz = 1 for each of its variables in terms of the other two near the point (2,-1,3). Attempt: Ok so using the IFT I was able to determine that I can only slze for y,z. But in the question they ask me to solve for y and z. z was not problem, but...

Hello everyone. I wish to get the solution to the following: x'(t) = [A*exp(B*t)-C]^(m) I can get the plotted solution by Matlab, but I wish to find the analytic solution by myself. Does anyone has some hints to help me in this? Thanks a lot for your help /Crevoise

Homework Statement Hello, When a current carrying loop (of any shape) is placed in a uniform magnetic field B , the field is given by MχB where M is the magnetic moment vector I*A where I Is current and A is the area vector. I want to know at which point or for which axis is the torque...

There is mention that dot products of vectors are used in backface removal in 3d graphics. Does anyone know of any article which explains the application of dot products to this area of graphics? I am looking for a concrete example.

A cylinder shaped container of tar has a diameter of 2m. If it is half full of tar with a density of 920 kg/(m^3) and is on it's side, find the force on each end. Helpful hints: 920 kg per m^3 is the mass density not the weight density. Take g= 9.8 m/ sec^2Please assist. I'm not sure at all how...

Homework Statement Hello, I'm trying to find the Taylor representation of a product of functions - the exponential of x times sin(y). Also for (x - y)sin(x+y). The Attempt at a Solution Well, I want to use the Cauchy product in both cases. I know the taylor representation of both...

Hi, I want to develop an application. For this purpose I found a site that deals with this kind of topic. Information is given about a software called (link and name deleted) have you heard about it? There are samples proiveded but they are in C# and I am not familiar with that programming...

I have a problem in my logic course which I can't get my head around: I have to show that there is a well formed formula \mathcal{A}(x_1) in the formal first order system for arithmetics, \mathcal{N}, with precisely one free variable x_1, such that \mathcal{A}(0^{(n)}) is a theorem in...

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How can I put laboratory equipment as a real-life application? Because I have this Formal Report that contains: Introduction Theory Methodology Data and Results Conclusion References and I don't have any idea how to start. can someone help me?

I applied for a job at a semitech company that makes NAND. Anyone know of a good book or source that I can find detailed structure information. The job posting also mentioned probe and param, which I don't know details about. Any help is appreciated.

Homework Statement http://img836.imageshack.us/img836/9994/27794040.jpg The Attempt at a Solution Here is the circuit I re-drew: http://img403.imageshack.us/img403/6752/dsc0048ga.jpg Working out: http://img857.imageshack.us/img857/5633/dsc0049mo.jpg I got the denominator correct, but my...

I was thinking that a car battery is a 12v source that delivers between 300 and 900 cold cranking camps. That'd put the cranking wattage at between 3600 watts and 10,800, right? Here's a car battery 'helper': http://goo.gl/Roo2l This is hypothetical at this point but what I was wondering...

Hi everyone :). I have one question about classical mechanics, which is illustrated in the attachment. The question is: for rigid bodies, how can the same external force F produce more overall movement in situation A) than in situation B)? This seems to contradict the conservation of energy...

Can someone help explain the difference between EDX(Energy-dispersive X-ray spectroscopy) vs. (XPS) X-ray photoelectron spectroscopy? Which is used for what application? Advantages/Disadvantages of each? From what I have been reading from documentation, they seem to be the same. Thanks.

We have this system of equations: \begin{cases} x'= -x + 2y & (1)\\ y' = -2x - y + e^{-t} & (2) \end{cases} where x(0) = 0 ; y(0) = 0 We apply the Laplace transform on (1) and (2) and get: (s + 1)X - 2Y = 0\\ 2X + (s + 1)Y = \frac{1}{s + 1} We can use elimination here...

but I have a headache. Here's the question: A laundry powder company wishes to produce a 27mm^3 washing powder capsule in the shape of a rectangular box. Due to production rescrictions, the width and the depth of the capsule must be equal lengths, and all dimensions of the capsule must be equal...

For a fixed number a, find the number of solutions $z^5+2z^3-z^2+z=a$ satisfying $\text{Re} \ z>0$. Not to sure on how to tackle this one.

Hello, I am using a 3 way NC, manifold mount bullet valve from mac. I am finding that with my current setup, the valve leaks vacuum in ports 2 and 3 (I was told this is intentional). For my application, I would like to use two 3-way valves to control vacuum from a reservoir to a suction cup...