Counterclockwise Circulation vs. Clockwise Circulation

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Homework Help Overview

The discussion revolves around calculating the circulation of a vector field F = (y - z)i + (z - x)j + (x + z)k around a surface defined by a paraboloid, specifically focusing on the distinction between clockwise and counterclockwise circulation.

Discussion Character

  • Conceptual clarification, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the calculation of the curl of the vector field and its implications for determining circulation. There is a focus on the sign of the circulation when considering clockwise versus counterclockwise directions. Questions are raised about the correctness of the area element used in the polar coordinates.

Discussion Status

Some participants have confirmed the calculation of -8π as the counterclockwise circulation, while others suggest rechecking the area element used in the calculations. There is an ongoing exploration of the implications of the sign change when interpreting the direction of circulation.

Contextual Notes

Participants are operating under the constraints of a homework problem, which may limit the information available for discussion. The focus is on ensuring the accuracy of mathematical elements and interpretations related to the problem setup.

Differentiate1
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Homework Statement


[/B]
Consider F = (y - z)i + (z - x)j + (x + z)k
Find circulation of F in the clockwise direction as seen from above, around the boundary of surface S defined by

z = 4 - x2 - y2
0 ≤ z ≤ 4

Homework Equations



∫∫ ∇xFk dA

The Attempt at a Solution



∇xF = i - 2j - 2k (after solving the cross product)
The curl of F dot k = -2

0 ≤ r ≤ 2
0 ≤ θ ≤ 2π

∫∫ -2 drdθ = ∫ -4 dθ = -8π

-8π is the counterclockwise circulation of F, but since the problem asks for the clockwise direction, would the answer just be 8π (opposite sign)?
 
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Differentiate1 said:

Homework Statement


[/B]
Consider F = (y - z)i + (z - x)j + (x + z)k
Find circulation of F in the clockwise direction as seen from above, around the boundary of surface S defined by

z = 4 - x2 - y2
0 ≤ z ≤ 4

Homework Equations



∫∫ ∇xFk dA

The Attempt at a Solution



∇xF = i - 2j - 2k (after solving the cross product)
The curl of F dot k = -2

0 ≤ r ≤ 2
0 ≤ θ ≤ 2π

∫∫ -2 drdθ = ∫ -4 dθ = -8π

-8π is the counterclockwise circulation of F, but since the problem asks for the clockwise direction, would the answer just be 8π (opposite sign)?

It will be if the ##-8\pi## is correct. Is your polar element of area correct?
 
Yes, I checked and -8π is the correct counterclockwise circulation.
Thanks.
 
You should recheck the area element again, even though you accidentally got the right answer.
 

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