Using Stokes law, calculate the work done along a curve

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Homework Help Overview

The discussion revolves around applying Stokes' law to calculate the work done along a curve defined as the edge of a spherical triangle in the first octant of a sphere described by the equation \(x^2+y^2+z^2=R^2\). The vector field in question is \(\vec{F}=(z^2,x^2,y^2)\).

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the need to parametrize the spherical triangle and express concerns about the complexity of their attempts. There are questions about the appropriateness of using Stokes' theorem versus calculating line integrals directly. Some participants suggest using spherical coordinates for the parametrization.

Discussion Status

The conversation is ongoing, with various interpretations of the problem being explored. Some participants have provided guidance on the use of spherical coordinates and the implications of orientation, while others express confusion about the parametrization and the nature of the boundary curve.

Contextual Notes

There is a lack of clarity regarding the orientation of the spherical triangle and how it affects the application of Stokes' theorem. Participants are also questioning the symmetry assumptions made in their parametrizations.

  • #31
Wow, it feels so good to understand that! :D

So, the final sign, the result, basically depends on weather the ##r_{\phi }\times r_{\theta}## and normal vector determined by right hand rule match. If they do not, than the result must be multiplied by -1.

Please correct me if I am wrong.
 
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  • #32
skrat said:
Wow, it feels so good to understand that! :D

So, the final sign, the result, basically depends on weather the ##r_{\phi }\times r_{\theta}## and normal vector determined by right hand rule match. If they do not, than the result must be multiplied by -1.

Please correct me if I am wrong.
$$\pm\int_0^{\frac \pi 2} \int_0^{\frac \pi 2}(\nabla \times \vec F) \cdot \vec r_\phi \times \vec r_\theta~
d\phi d\theta$$
We are talking about the choice of the ##\pm## sign in the statement of Stoke's theorem. Whether the final answer of the problem is positive or negative is a different question and it depends on what the integrand is.
 

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