It's actually a very subtle anti-counterfitting strategy. If you make it look correct, then the bill is fake. ;-) On Mar 18, 2013, at 4:13 PM, Henry Baker wrote:

Correct, although even if the chains/wires are supporting weight, their shapes for the free portions should still be _sections_ of catenaries.

Thus, even the parabolic shape on a typical (Golden Gate-style) suspension bridge is a piecewise approximation from bits of catenary shapes.

I hadn't realized it until I did some searching a few years ago, but the people most interested in catenaries on a day-to-day basis are people on ships who have to worry about the lengths and stresses on anchor chains.

At 01:03 PM 3/18/2013, Michael Kleber wrote:

...

Are you talking about the chains holding up the light? There's a vertical chain as well, so the "mathematically correct" shape depends on the relative tensions of the chains. As long as the bill matches reality, catenary vs. parabola is irrelevant.

http://0.tqn.com/d/dc/1/0/C/J/whitehouse2.jpg

--Michael

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