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# Path integral question watch

1. How would you approach such a question?
2. Honestly? No idea - the "elliptic arcs" bit is stumping me. What are the earlier parts of the question? Do you have any idea what topic you are supposed to use to answer this?
3. (Original post by TwiMaster)

How would you approach such a question?
Looks like a calculus of variations problem, but I think we need more info.
4. (Original post by DFranklin)
Honestly? No idea - the "elliptic arcs" bit is stumping me. What are the earlier parts of the question? Do you have any idea what topic you are supposed to use to answer this?

Those are the earlier parts & I think Green's theorem may be applicable here? Don't exactly know how though
5. Isn't the integrand an exact differential?
6. (Original post by RichE)
Isn't the integrand an exact differential?
Well, I was thinking the elliptical curve thing had to be a red herriing, so it wouldn't surprise me. I can't remember what the rule is for it though, so I'll leave it in your hands
7. (Original post by DFranklin)
Well, I was thinking the elliptical curve thing had to be a red herriing, so it wouldn't surprise me. I can't remember what the rule is for it though, so I'll leave it in your hands
I'll wait to see if I've given hint enough.
8. (Original post by RichE)
Isn't the integrand an exact differential?
Yes, well spotted - but doesn't that make it trivial? [and PRSOM]
9. (Original post by DFranklin)
Well, I was thinking the elliptical curve thing had to be a red herriing, so it wouldn't surprise me. I can't remember what the rule is for it though, so I'll leave it in your hands
The rule for an exact differential or the elliptical curve bit? If it's the former, then it just means that the integrand is of the form for some suitable f.
10. (Original post by atsruser)
The rule for an exact differential or the elliptical curve bit? If it's the former, then it just means that the integrand is of the form for some suitable f.
OK, you made me look it up. The test where you the dx term and it has to equal the dy term.

Edit: as Rich has pointed out, this is the wrong way around. the dy term and vice versa.
11. (Original post by DFranklin)
OK, you made me look it up. The test where you the dx term and it has to equal the dy term.
other way around i think
12. (Original post by DFranklin)
OK, you made me look it up. The test where you the dx term and it has to equal the dy term.
Right. The elliptical curve bit is misdirection, I think. [I think you swapped the derivatives though]
13. (Original post by RichE)
other way around i think
Arghh! Read the wiki page wrong. Sigh. The eye operations (March, hopefully) can't come soon enough...

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