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## Main Question or Discussion Point

This is from my course notes

http://img28.imageshack.us/img28/2630/ckyl.jpg [Broken]

In line 3, there's the integral [tex]\int_0^t ||y'(s)||ds[/tex] which represents the length of the curve as a function of t (which I am thinking of as time). Here, I think s is a dummy variable for time.

The equation in line 4, however, says that s is an element of [0, |C|] which seems to imply that s iis a length. Here, it makes sense, because [itex]\sigma[/itex] maps time to length, and so [itex]\sigma^{-1}[/itex] maps length back to time, which goes into the function y and y(t) is spit out (the position vector function of the curve.

But back to the integrand, ||y'(s)|| where the variable s is a length makes no sense to me because y is meant to be function of time, not length. Is there something I'm misunderstanding here?

Thanks

http://img28.imageshack.us/img28/2630/ckyl.jpg [Broken]

In line 3, there's the integral [tex]\int_0^t ||y'(s)||ds[/tex] which represents the length of the curve as a function of t (which I am thinking of as time). Here, I think s is a dummy variable for time.

The equation in line 4, however, says that s is an element of [0, |C|] which seems to imply that s iis a length. Here, it makes sense, because [itex]\sigma[/itex] maps time to length, and so [itex]\sigma^{-1}[/itex] maps length back to time, which goes into the function y and y(t) is spit out (the position vector function of the curve.

But back to the integrand, ||y'(s)|| where the variable s is a length makes no sense to me because y is meant to be function of time, not length. Is there something I'm misunderstanding here?

Thanks

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