Divergence Theorem: Volume and Surface Integral Solutions

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SUMMARY

The discussion centers on the application of the Divergence Theorem using a vector field defined in spherical coordinates: \(\vec{v} = r \cos \theta \hat{r} + r \sin \theta \hat{\theta} + r \sin \theta \cos \phi \hat{\phi}\). The volume integral over a hemisphere resting on the xy-plane yields a result of \(10R\pi\). However, the surface integral calculation initially presented was incorrect; the correct differential area element is \(d\vec{a} = R^2 \sin \theta d\theta d\phi \hat{r}\), not \(R^3\). This correction is crucial for aligning the results of both integrals.

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Phymath
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ok well basically use the divergence thrm on this..
[tex] \vec{v} = rcos\theta \hat{r} + rsin\theta\hat{\theta} + rsin\theta cos \phi \hat{\phi}[/tex]

so i did (remember spherical coords) i get..
[tex]5cos \theta - sin\phi[/tex]
taking that over the volume of a hemisphere resting on the xy-plane i get [tex]10R \pi[/tex]

however with the surface intergral i use [tex]d\vec{a} = R^3 sin\theta d\theta d\phi \hat{r}[/tex] where R is the radius of the sphere doing that intergral gives me something obvioiusly R^3 which is not what I'm getting in the volume intergral any help or explanations (if its i need to take the surface of the bottom of the hemi sphere aka the xy-plane in a circle that will suck but let me know!
 
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however with the surface intergral i use [tex]d\vec{a} = R^3 sin\theta d\theta d\phi \hat{r}[/tex] where R is the radius of the sphere doing that intergral
Your surface integral is wrong.
[tex]d\vec{a} = R^2 sin\theta d\theta d\phi \hat{r}[/tex] not R3.
 

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