Line integral around a circle, using polar coordinates

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SUMMARY

The discussion focuses on calculating the line integral of a force field defined in planar polar coordinates, specifically F(p,w) = 2p + sin(w)e_p + cos(w)e_w, over a circular path where p = 2 and 0 ≤ w ≤ 2π. The primary challenge is determining the "dr" term in the line integral definition, ∫_0^{2π} F(p,w) · dr. Participants emphasize the need for parameterization of the path, suggesting that w serves as an effective parameter for this integral calculation.

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iAlexN
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Given the force (derived from a potential in planar polar coordinates)

F(p,w) = 2p+sin(w)e_p+cos(w)e_w Where e_p and e_w are unit vectors

How do I calculate the line integral over a circumference that is defined as:
p = 2
0 ≤ w ≤ 2pi

Using the definition of a line integral \int_0^{2pi} \! F(p,w) . \, \mathrm{d}r

What confuses me though is what the "dr" term would be in this case? Do I need to do some form of parametrisation, in that case, how?

Thank you!
 
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I am confused by your use of "p" and "w" for both the parameters and the unit vector subscripts. In particular, does e_w change when w changes? Or is it fixed?

In any case, since e_p and e_w are unit vectors, you can write them as (cos_p, sin_p) and (cos_w, sin_w). The values of (cos_w and sin_w) may be functions of w.

I think you will have to parameterize the path in order to define the line integral. Since w runs from 0 to 2*pi, I think that is a good parameter to use.
 

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