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what's the deal? - Mar 18, 2004 at 3:07PM | |
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desolderthis 2 Posts |
Some things really test my faith in math |
Replies to what's the deal?
order matters - Mar 18 2004 3:39PM | |
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Gary Society of Physics... 293 Posts |
I guess the first thing I would say is that you have to be careful about the order in which you do things...for example d/dx(x^3) = 3x^2 and that is not the same as NSF Program Director (on assignment from the AIP and the Society of Physics Students to serve as the Robert Noyce Scholarship Program Director at the National Science Foundation) |
- Mar 21 2004 9:00PM | |
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Damian Cypress 1 Posts |
First off...you have to recall that phi(r).You have to use the chain rule to properly differentiate the second guy. The answer is 2/r*d(phi)/dr+d2(phi)/dr2. The first guy just gives you the second term of the second guy. phew...did that make sense? Be careful about spherical coordinates, there's a nasty singularity at the origin. For a rigorous discussion of this topic check out Electrodynamics by Griffin, an excellent upper div text on the subject. |
Re: what's the deal? - Jul 13 2004 10:05AM | |
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Dave San Marcos, Texas 413 Posts |
The difference is that in the second case, you are taking the partial derivative of a product, and so must use the product rule. This gives you two terms instead of the single term that results from the first expression. Try not to become a man of success, but rather try to become a man of value -- Albert Einstein |