Line integral around a circle, using polar coordinates

In summary, the conversation discusses the calculation of a line integral over a circumference defined by p=2 and 0≤w≤2pi. The force function is given in terms of p and w as F(p,w)=2p+sin(w)e_p+cos(w)e_w, where e_p and e_w are unit vectors. It is suggested to use parametrization in order to define the line integral and the values of (cos_w, sin_w) may be functions of w.
  • #1
iAlexN
16
0
Given the force (derived from a potential in planar polar coordinates)

[tex]F(p,w) = 2p+sin(w)e_p+cos(w)e_w [/tex] 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 [tex] \int_0^{2pi} \! F(p,w) . \, \mathrm{d}r [/tex]

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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  • #2
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.
 

Related to Line integral around a circle, using polar coordinates

1. What is a line integral around a circle using polar coordinates?

A line integral around a circle using polar coordinates is a mathematical concept that calculates the total value of a vector field along a circular path using polar coordinates instead of Cartesian coordinates.

2. Why is it useful to use polar coordinates for a line integral around a circle?

Polar coordinates are useful for a line integral around a circle because they simplify the calculations and make it easier to understand the behavior of the vector field along the circular path. It also allows for a more intuitive understanding of the geometry of the circle.

3. How do you calculate a line integral around a circle using polar coordinates?

To calculate a line integral around a circle using polar coordinates, you first need to convert the Cartesian coordinates of the circle into polar coordinates. Then, you can use the formula ∫F(r,θ) ds = ∫F(r,θ) r dθ, where F is the vector field, r is the radius, and θ is the angle.

4. What is the significance of a line integral around a circle using polar coordinates?

A line integral around a circle using polar coordinates is significant because it allows for a better understanding of the behavior of a vector field along a circular path. It also has practical applications in physics, engineering, and other fields.

5. Are there any limitations to using polar coordinates for a line integral around a circle?

While polar coordinates are useful for calculating a line integral around a circle, they may not be suitable for more complex shapes or paths. In these cases, it may be necessary to use other coordinate systems or techniques to calculate the line integral.

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