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 On Mon, Mar 18, 2013 at 3:43 PM, Henry Baker <hbaker1@pipeline.com> wrote:
If the arch in St. Louis had been a bit larger -- i.e., such that its span were not negligible compared with the radius of the round Earth -- what would be its ideal shape?
At 12:31 PM 3/18/2013, Adam P. Goucher wrote:
Catenaries and parabolae are only distinguishable at large scales:
http://en.wikipedia.org/wiki/File:Comparison_catenary_parabola.svg
----- Original Message ----- From: James Propp Sent: 03/18/13 07:03 PM To: math-fun Subject: [math-fun] Twenty-dollar question
Is the hanging chain on the back of the $20 bill mathematically correct? It looks more like a parabola than a catenary to me.
Jim Propp
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