Recent content by Weather Freak

Hi Folks, I think this is the best place to post this, as I see a couple of other fluid questions in here. For some reason, everyone always defines stream function as only applying to 2D flow. The total flow is represented by \vec{U}, where \vec{U} is a 3 dimensional vector with components...

So I have what I think is going to be a silly matrix algebra question. I'm performing a linear regression, using standard matrix algebra: Y = XA (all are matrices) I have found my coefficients (A) and now I wish to use that information to get X as a function of Y. If this were a normal...

Hi Folks, I have a question about determinants that is probably quite simple. I know that if you have a matrix and you interchange rows, the determinant changes. However, if you cyclically change the rows up or down, still in order, the determinant does not change. What is the theorem or...

Thanks a lot, that definitely answers the question! The trick of each row being the gradient of Fi really makes it easy to remember as well.

First off, this is not a homework problem, but rather is an issue that I've had for a while not and haven't quite been able to reason out to my satisfaction on my own. u-vector = ui + vj + wk What is grad(u-vector)? I know what the gradient of a function is, but this is the gradient of a...

www.easternuswx.com is my favorite.

All official measurements are taken about 1.5 meters above the ground, in a white shelter that is ventilated at a certain rate. The white color (ideally) gives the shelter a very high albedo, close to 100%, which means that it won't absorb sunlight and warm up... the ventilation keeps the air...

Awesome! Thanks :)

Homework Statement Find the work done by the force field F(x,y) = x*sin(y) i-hat + y j-hat on a particle that moves along the parabola y = x^2 from (-1,1) to (2,4). 2. The attempt at a solution Please see attached file. The answer I get seems really, really, complicated and I have a...

Okay, I think I get it now, thanks! One more thing though... if the work ends up being zero, does that necessarily imply that the vector field is conservative, or is it only true the other way around?

Homework Statement Find the work done by the force field F(x,y) = (x+2y^2)j as an object moves once counterclockwise about the circle (x-2^2+y^2=1 by first evaluating the integral directly then use Green's Theorem and evaluate the double integral. Homework Equations W = F*D*cos(theta)...

Sure, we can "see" them and "interact" with them in these ways, but it's more of an interaction with a collection of them... For instance, if I place my hands on a Van de Graff, I can feel and see the consequence of electrons, but I don't actually see the individual electrons. I don't see one...

Well we can feel birds, we can hear birds, we can see birds, we can interact with birds. When I touch a bird I know that I am touching it because I can see myself place my hand on it. It's tough to have this kind of confidence when none of the major senses can actively detect an electron...

I see, so it's not a sphere at all, but rather the sphere is just how it is represented in the textbooks...?

I think I get it... basically we have no idea what it actually looks like and the pictures in all the books are simply our best guess? And the concept of an electron is a subatomic particle which has all the properties that we attribute to an "electron"?