# Recent content by mathwurkz

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. ### Why the earth is rotating along its axis?

I was on Earth when I made that statement. I guess I should have taken my spacecraft and observed the moon's rotation from somewhere in outer space.
5. ### Why the earth is rotating along its axis?

Correct me if I am wrong, but I recall that the moon is a body that does not rotate on an axis so one side of the moon always faces Earth.. Hence, you might have heard of the saying, "dark side of the moon" which we never see due to the lack of rotation.
6. ### Christmas from from an Engineer's Perspective

You need a sixth clause (pun intended): Santa can defy the laws of the universe as we know it. Ya 6 santa's running around ought to do it. You can do the math.
7. ### Differential Equation and Fourier Series

Ok. I got it now thnks.
8. ### 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...
9. ### 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...
10. ### 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...
11. ### 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
12. ### How would I find the inverse laplace transform

But doesn't that integral have to be evaluated to get the answer? That's what I can't evaluate. Hence, I went looking to try partial fractions which I can't get either.
13. ### How would I find the inverse laplace transform

The original question was to solve a differential equation for i(t) for LR series electrical circuit... L \frac{di(t)}{dt} + Ri(t) = E(t) Given the condition i(0) = 0 and E(t) is the square wave function. So I looked up the square wave function and got E(t) = 1 - H(t-1) + H(t-2) -...
14. ### 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...