I remember being so excited when I first found out about Wikipedia by the idea that I could add all of my copious bits of knowledge to it, making it better. That feeling lasted for about an hour, before I realized that there really wasn’t much that I knew that the lazyweb didn’t already know, usually with much more depth that I did.

Today, though I was able to add a little bit of my brain to the mix. I was looking at this guy’s weird contraption for tracing out parabolic volumes (for large solar cookers), but I had a little trouble figuring out why it worked.

Surprisingly, the Wikipedia article on parabolas was no help. Once I figured it out, though, I was able to make a minor adjustment to one of the diagrams there and add it. A good feeling ensued.

Details: The Instructable works on a weird mechanical contraption that relies on the principle illustrated in the diagram that I added:

“Parabolic curve showing arbitrary line (L), focus (F), and vertex (V). L is an arbitrary line perpendicular to the axis of symmetry and opposite the focus of the parabola from the vertex (i.e. farther from V than from F.) The length of any line F - Pn - Qn is the same. This is similar to saying that a parabola is an ellipse, but with one focal point at infinity.”

The wording is a little unwieldy; feel free to tighten it up!

Related Posts:

• N’Dombolo (September, 2007)
• Feingold on the D.R. Congo (October, 2007)
• Seeing in Color (October, 2008)
• Fighting Beyond the Country Club Walls (August, 2007)
• JSLoad (December, 2007)

This entry was posted on Thursday, December 13th, 2007 at 12:21 pm and is filed under instructables, mathematics, personal. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.