Uses of Ellipses
Date: 04/02/2003 at 20:54:06 From: Rachel Subject: Uses of Ellipses I see there are examples of conic sections in daily life on this site, but I can't find ellipses. How are ellipses used in real life?
Date: 04/03/2003 at 14:16:13 From: Doctor Douglas Subject: Re: Uses of Ellipses Hi, Rachel, In addition to the astronomy applications mentioned in Who uses Ellipses? http://mathforum.org/library/drmath/view/54787.html Here are some other places where you will find ellipses: The shape of a spotlight on a planar surface is in most cases an ellipse. In some cases it may be a circle. If you cut a cylinder at an angle, you will get elliptical sections. This can have important applications in optics (lenses and mirrors can be elliptical in shape), or in the kitchen (where one might cut vegetables or sausage along a "bias cut" in order to obtain pieces that have the same thickness, but have more surface area exposed. Some tanks are in fact elliptical (not circular) in cross section. This gives them a high capacity, but with a lower center-of-gravity, so that they are more stable when being transported. And they're shorter, so that they can pass under a low bridge. You might see these tanks transporting heating oil or gasoline on the highway The ellipse is found in art and architecture, and you may be familiar with the Ellipse, part of a President's Park South (a National Park in Washington, DC, just south of the White House). Ellipses (or half-ellipses) are sometimes used as fins, or airfoils in structures that move through the air. The elliptical shape reduces drag. On a bicycle, you might find a chainwheel (the gear that is connected to the pedal cranks) that is approximately elliptical in shape. Here the difference between the major and minor axes of the ellipse is used to account for differences in the speed and force applied, because your legs push and pull more effectively when the pedals are arranged so that one pedal is in front and one is in back, than when the pedals are in the "dead zone" (when one pedal is up and one pedal is down). - Doctor Douglas, The Math Forum http://mathforum.org/dr.math/
Search the Dr. Math Library:
Ask Dr. MathTM
© 1994- The Math Forum at NCTM. All rights reserved.