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WD Line Integrals

Calculate the work done by the force field F(x,y,z)=(y2,z2,x2)F(x,y,z)=(y^2,z^2,x^2) along the curve of intersection of the sphere x2+y2+z2=1x^2+y^2+z^2=1, the cylinder x2+y2=xx^2+y^2=x, and the halfspace z>0z>0. The path is traversed in a direction that appears clockwise when viewed from the high above the xyxy-plane.

How do I even find the path for starters... after that it is straight forward.

I know what the sphere would look like in the xyz plane but not the cylinder. How do you sketch the cylinder?
(edited 9 years ago)

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Reply 1
Original post by cooldudeman
Calculate the work done by the force field F(x,y,z)=(y2,z2,x2)F(x,y,z)=(y^2,z^2,x^2) along the curve of intersection of the sphere x2+y2+z2=1x^2+y^2+z^2=1, the cylinder x2+y2=xx^2+y^2=x, and the halfspace z>0z>0. The path is traversed in a direction that appears clockwise when viewed from the high above the xyxy-plane.

How do I even find the path for starters... after that it is straight forward.

I know what the sphere would look like in the xyz plane but not the cylinder. How do you sketch the cylinder?


simultaneous equations?
Original post by TeeEm
simultaneous equations?


Ok so subbing in the cylinder equation the way it is written to the sphere gives x+z^2=1 which would some kind of parabola. What variable do you rearrange this new equation to?
Reply 3
Original post by cooldudeman
Ok so subbing in the cylinder equation the way it is written to the sphere gives x+z^2=1 which would some kind of parabola. What variable do you rearrange this new equation to?


some parametric representation
when you need the parameter ends
start and finish for t
Original post by TeeEm
some parametric representation
when you need the parameter ends
start and finish for t


So so if we rearrange it to x=1-z^2, so let r(t)=1-t^2 but I have no idea how to find the limits...

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Reply 5
Original post by cooldudeman
So so if we rearrange it to x=1-z^2, so let r(t)=1-t^2 but I have no idea how to find the limits...

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I need to look at the question in detail (sometime tomorrow afternoon) as I am in the middle of my own work and also helping another individual.

atsruser is around and can help you at present.
Original post by TeeEm
I need to look at the question in detail (sometime tomorrow afternoon) as I am in the middle of my own work and also helping another individual.

atsruser is around and can help you at present.


Ok ill try PM him

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Reply 7
Original post by cooldudeman
Ok ill try PM him

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he replied to your post
Original post by TeeEm
he replied to your post


Turns put he's busy too. Damn oh well.

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Reply 9
Original post by cooldudeman
Turns put he's busy too. Damn oh well.

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I am looking at the question now
Original post by cooldudeman
Turns put he's busy too. Damn oh well.

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Please ignore my earlier post. I don't think it makes sense and I'm too tired to think about this now. Sorry.
Original post by TeeEm
I am looking at the question now


Thanks please let me know

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Reply 12
Original post by cooldudeman
Thanks please let me know

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very hard to picture

pulling20hair20out201_zpsbc251cc8.png

definitely I am too tired to complete this tonight
Reply 13
Original post by cooldudeman
Thanks please let me know

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very hard to picture

pulling20hair20out201_zpsbc251cc8.png

definitely I am too tired to complete this tonight

do you know what the answer is meant to be
Original post by TeeEm
very hard to picture

pulling20hair20out201_zpsbc251cc8.png

definitely I am too tired to complete this tonight

do you know what the answer is meant to be


I actually don't. Thanks please look at it when u can.

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Reply 15
Original post by cooldudeman
I actually don't. Thanks please look at it when u can.

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can you check if this field is conservative!!!
Reply 16
Original post by cooldudeman
I actually don't. Thanks please look at it when u can.

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I got an answer of pi/4

if my initial modelling is correct (parameterization of the path) then it is all correct.
Original post by TeeEm
I got an answer of pi/4

if my initial modelling is correct (parameterization of the path) then it is all correct.


How did you find the path though?
Reply 18
Original post by cooldudeman
How did you find the path though?


I will attach my attempt and by no means solution ...

IMG_0001.pdf
Original post by TeeEm
I will attach my attempt and by no means solution ...

IMG_0001.pdf


thanks looking at it now! I'll have another solid go and see if I get the same. I'll let you know by tomorrow.

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