# Search results

1. ### Studying How can I buy these textbooks

There are "Low Price" Editions and "International" Editions of textbooks that are equivalent to the editions printed in the US, except that they are much CHEAPER in every sense of the word. I would like to ask if anyone knows where I can find a listing of these books and possibly purchase them...
2. ### Problem with Exercise and Sweat

Hey there. I've been having this problem and hoping someone has had some experience dealing with this. Everytime I exercise, instead of perspiration coming from my head, I get an itch with a little flakiness instead. My head doesn't seem to sweat anymore. The same itch comes when I go into...
3. ### Styrofoam, Deflection, and Treatment

Hi I am in a competition where I have to use the deflection of a polystyrene beam to launch a projectile. Styrofoam is rather brittle but it is the only material we are allowed to use (it's cheap). I have a geometry all set but I was wondering if there is any possible way to treat the styrofoam...
4. ### Differential Equation and Fourier Series

I have this problem. I would appreciate it if anyone can help me get started. Question: Consider the differential equation: \frac{d^2 y(x)}{dx^2} + y(x) = f(x) \ \ ; \ \ 0 \leq x \leq L \\ The boundard conditions for y(x) are: y(0) = y(L) = 0 \\ Here f(x) is assumed to be a known function...
5. ### Complex Fourier Series and Phase Spectra

Please check my solution and I need help on understanding the second part of the question. Q:Obtain the complex form of the fourier series of the sawtooth function. f(t) = \frac{2t}{T} \ \ \ 0 < t < 2T\\ So if the period is 2l = 2T then l = T \\ c_n = \frac{1}{2l} \int_{-l}^{l} f(x) e^{in\pi...
6. ### Material Science, Material Selection Question

I have a problem with this homework. Please have a look at my work and see if it checks out. ROCKET FUEL TANK A company has asked you to help their business in space tourism. They have designed a rocket that will be powered by nitrous oxide (reacted with rubber), and you are to select...
7. ### Surface Integral

Hi! I don't know how to approach this problem. I need a little bit of help please. Here is the problem: Find the surface area of that portion of the sphere x^2 +y^2 + z^2 =a^2 that is above the xy-plane and within the cylinder x^2 + y^2 = b^2, 0 \leq b \leq a
8. ### How would I find the inverse laplace transform

Hi How would I find the inverse laplace transform of this? I(s) = \left( \frac{1}{s(1+e^{-s})}\right) \left( \frac{1}{Ls+R}\right) i(t)=??? L, R are constants. I recognize the first term to be a geometric progression (square-wave function). With an infinite number of terms in that...
9. ### Where did I go wrong? [Laplace Transform]

L is Laplace Transform operator. Question is: Let f(t) = t^2. Derive L[f] from L So I know f(1) =1 and L = \frac{1}{s} Carrying out the Transform... L[f] = \int_{0}^{\infty} e^{-st}t^2 dt Integration by parts u = t^2, dv = e^{-st} dt I do the integration, the uv...
10. ### Looking for a proof

Hey guys, how can this Laplace transform be proven. I always see it in the tables but don't know how it came to be. L[t^n] = \frac{n!}{s^{n+1}}
11. ### Mechanics Problem, Cannot understand

Here is the problem. A car starts moving rectilinearly, first with acceleration \omega = 5.0 m/s^2 (the initial velocity is equal to zero), then uniformly, and finally, decelerating at the same rate \omega , comes to a stop. The total time of motion equals \tau = 25 s. The average...
12. ### Counting Question

I'm taking a crack at learning probability and statistics starting from the basics. Anyways here is the question. --- A fair coin is tossed 10 times and the sequence of scores recorded. How many sequences are there? How many sequences are there that contain exactly 3 heads? ---...
13. ### How do you pronounce the name Xenocrates

How do you pronounce the name "Xenocrates" Hi. Question. How do you pronounce the name "Xenocrates" ? 2) I was reading about the first combinatorial problem which was formulated by Xenocrates. It asks how many syllables can be made from the letters of the alphabet. And the solution was...
14. ### Is There an AutoCAD Alternative?

Title says it all. I am wondering if there is any kind of freeware/shareware software that does the same thing AutoCAD does? I am taking an class and it is a level one course. The scope of the course only focuses on two dimensional drawings so the alternative doesn't have to be all that...
15. ### Coordination Number and Geometry

I am trying to understand a sample problem in this text I have about materials science. The question is to calculate the minimum radius ration for a coordination number of 8. The coordination geometry is cubic. What I don't understand in this problem is one of the two equations they use to solve...
16. ### Open Attached Images

Hi! Whenever I am going through a post on this forum and try to open a link, in the "attached images" block of a post, to an image posted by another member, I am unable to open it. I get the following. Do I need something on my account to access attached images on posts? How do I get it? I...