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- Jul 20th 2014, 05:37 AMkaemperDivF, Flux integral, centroid
- Jul 20th 2014, 12:36 PMHallsofIvyRe: DivF, Flux integral, centroid
In the first problem you are given and are asked to find it flux out of the ball . (you have but that is corrected in the integral so I assume that was a typo).

You do the integral by writing it as and then try to calculate , , and . You realize, do you not that those are just the coordinates of the**center**of the figure? Here that figure is a sphere with center at (2, 0, 3) so you should be able to write down, with no calculation at all, that , , and .

I have no idea at all how you got " "! You understand, don't you, that the x coordinate of the centroid of a figure is a**number**not a function of x? And it certainly is NOT the case that ! - Jul 27th 2014, 11:37 AMkaemperRe: DivF, Flux integral, centroid
I give sincere thanks to HallsofIvy who has generously presented me with the most promising answer imaginable. I address you directly, HallsofIvy:

I do have received teaching in pre-calculus math: I was just insecure about the term "centroid".

Yours,

Student, Chemistry (Bachelor) at University of Southern Denmark (SDU). - Jul 27th 2014, 12:45 PMkaemperRe: DivF, Flux integral, centroid
So the flux out of the ball is the following:

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