Is the Surface Integral Equivalent to the Traditional Definition?

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Discussion Overview

The discussion centers around the equivalence of surface integrals and line integrals in vector calculus, exploring definitions and potential connections between the two concepts. It includes theoretical aspects and mathematical reasoning.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant presents definitions of line and surface integrals, suggesting a potential equivalence between them using the position vector and differential elements.
  • Another participant asserts that surface integrals and line integrals are fundamentally different, emphasizing that one is a double integral and the other a single integral, while referencing Stokes' Theorem as a connection.
  • A participant reiterates their definition of the surface integral using a double integral and questions the validity of the traditional definition, seeking confirmation of their equivalence.
  • Another participant challenges the definitions provided, specifically criticizing the notation used for expressing differential elements as nonsensical.

Areas of Agreement / Disagreement

Participants express disagreement regarding the equivalence of surface integrals and line integrals, with some supporting the idea of equivalence while others firmly reject it. The discussion remains unresolved.

Contextual Notes

There are unresolved issues regarding the definitions and mathematical expressions used, particularly concerning the notation for differential elements and the implications of Stokes' Theorem.

Jhenrique
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Hello!

The definition of Line Integral can be this:
[tex]\int_s\vec{f}\cdot d\vec{r}=\int_s(f_1dx+f_2dy+f_3dz)[/tex]

And the definition of Surface Integral can be this:
[tex]\int\int_S(f_1dydz+f_2dzdx+f_3dxdy)[/tex]

However, in actually:
[tex]\\dx=dy\wedge dz \\dy=dz\wedge dx \\dz=dx\wedge dy[/tex]
What do the Surface Integral be equal to:
[tex]\int\int_S(f_1dy\wedge dz+f_2dz\wedge dx+f_3dx\wedge dy)=\int\int_S(f_1dx+f_2dy+f_3dz)=\int\int_S\vec{f}\cdot d\vec{r}[/tex]

I know, I know... I know that, generally, the definition to Integral Surface is:
[tex]\int\int_S\vec{f}\cdot \hat{n}\;dS[/tex]
I until like this definition when compared to its respective Line Integral:
[tex]\int_s\vec{f}\cdot \hat{t}\;ds[/tex]

But, is correct to definite the Surface Integral as:
[tex]\int\int_S\vec{f}\cdot d\vec{r}[/tex]
being
[tex]d\vec{r}=(dx,dy,dz)[/tex]
?
 
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No, the surface integral is, as you say, a double integral while the path integral is a single integral. They are NOT the same thing. They can, of course, be connected by, for example, the Stoke's Theorem that says that the integral of the curl of [itex]\vec{F}[/itex] over a surface is the same as the integral of [itex]\vec{F}[/itex] around the boundary of the surface.
 
But I definited the Surface Integral with a double integral (as you can see below or above)
[tex]\int\int_S\vec{f}\cdot d\vec{r}[/tex]
with the only difference that I used the position vector r, like in Line Integral. But, second the identities above, to define the Surface integral with ·dr is equivalent to traditional definition, with ·ndS. Correct!?
 
Jhenrique said:
the Surface integral with ·dr is equivalent to traditional definition, with ·ndS. Correct!?

what? your definitions make no sense. [itex]``dx = dy \wedge dz''[/itex] is literally nonsensical.
 

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