Calculating Divergence With Spherical Coords

maherelharake
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Homework Statement



Calculate div v.

v= r sin(θ) r + r sin(2θ) cos(φ) θ + r cos(2θ) φ.


Homework Equations





The Attempt at a Solution



I've never had to do a problem like this using spherical coords, so I am not sure where to start. I have the general formula though.
 
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What you've shown is not a vector. I'm guessing you omitted putting hats on some of the symbols, like \hat r. But if you have the formula for a gradient in spherical coordinates, just use it. Find the functions in front of \hat r, \hat \theta and \hat \phi and use it.
 
What I have so far is attached (as 6B). Am I on the right track?


http://i77.photobucket.com/albums/j72/maherelharake/photo-25.jpg
 
maherelharake said:
What I have so far is attached (as 6B). Am I on the right track?


http://i77.photobucket.com/albums/j72/maherelharake/photo-25.jpg

Some parts are right. You got some extra hats hanging around. The divergence should be a scalar, right? It shouldn't have any vector parts. And you haven't expanded your derivatives yet.
 
Thank you for responding.
I was still working on it, I just wanted to see if I was on the right track. What about now?
 

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There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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