Proving Vector Calculus: Cyclic Integral of (r dot ds)=0

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SUMMARY

The cyclic integral of the dot product of the position vector \( \mathbf{r} \) and the differential element \( \mathbf{ds} \) is proven to be zero using Green's Theorem. Specifically, the integral \( \oint \mathbf{r} \cdot \mathbf{ds} = 0 \) holds true because the curl of the position vector \( \mathbf{r} \) is zero, indicating that the integral over any closed curve results in zero. This conclusion is derived from the fundamental properties of vector calculus and the application of Green's Theorem.

PREREQUISITES
  • Understanding of vector calculus concepts, particularly curl and line integrals.
  • Familiarity with Green's Theorem and its applications in vector fields.
  • Knowledge of position vectors and their representation in Cartesian coordinates.
  • Basic proficiency in mathematical notation and symbols used in calculus.
NEXT STEPS
  • Study Green's Theorem in detail to understand its implications in vector calculus.
  • Learn about the properties of curl and how to compute it for various vector fields.
  • Explore examples of line integrals and their applications in physics and engineering.
  • Investigate the relationship between vector fields and their potential functions.
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This discussion is beneficial for students and professionals in mathematics, physics, and engineering who are looking to deepen their understanding of vector calculus and its applications in proving integral theorems.

Suvadip
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How to prove that

cyclic integral of (r dot ds) =0

(symbols having usual meanings).

Please help me


2) It is always possible to find curl when vector function is known, but how to find the vector when its curl is known.
 
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if you are asking how to prove that
\oint \overset{ }{ \overset{\to }{r}}.\overset{ }{\overset{\to }{\text{ds}}}=0

where r is the position vector, that is r={x , y}; the we can prove it using green's theorem. "the integral of a vector field around a closed curve equal de integral of the rotational of the field over the surface enclosed"

and rot(r)=0, as you can check; so the integral we are considering equals the integral of 0 over the surface enclosed by the curve S; which is 0 of course, since the integrand is 0.
 
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