# Talk:Prolate spheroid

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Field: Geometry

## Missing equation of the surface

This article has equations for two integrals, *volume* and *surface area*, no equation to define the object itself - it's *surface*. Can anyone add this? MichaelRWolf (talk)

## Questions

I have two questions about this article if anyone is watching:

• What is the difference between and an oblate spheroid and a prolate spheroid?
• What does 'polar' mean in this context?

Abtract 23:09, 24 January 2007 (UTC)

This difference between an oblate and prolate spheroids are that oblate spheroids bulge at their equator and prolate spheroids bulge at their poles. Polar refers to the poles, simalar to the North and South pole. Kamope · talk · contributions 15:08, 3 February 2007 (UTC)
For the 2nd question, polar diameter means "the diameter mesured between the poles". Kamope · talk · contributions 15:10, 3 February 2007 (UTC)

I get the distinction between prolate and oblate, however; given a non-rotating sphere with no markings, where is the equator and where are the poles? WRT its use to describe a football, if a quarterback throws an awkward 'duck' of a pass, is it possible that the football becomes an oblate spheroid based on its rotation? poop. —Preceding unsigned comment added by 209.221.240.193 (talk) 22:17, 8 September 2010 (UTC)

I believe the orientation ("markings") of the spheroid is determined by the shape...not the other way around. Consider Earth, itself: It is tilted at an angle, thus what we consider north-south on the planet is not north-south relative to the solar system (and, probably, what is north-south to the solar system may not be north-south relative to the universe——whatever that may be!). As for what is the equator and what are the poles, if you look at the face of a football, if it is pointed end up-down, it would seem to be prolate, but if it is laying on its side, it looks like it could be oblate. But now spin it sideways, so that one of the pointed ends is facing you: The shape is such that the pointed ends can only be the poles and the mid-vertical circle is the equator, regardless of the football's tilt.  ~Kaimbridge~ (talk) 14:18, 9 September 2010 (UTC)

## American football?

"The prolate spheroid is the shape of the ball in some sports, the most popular of which are Australian Football, Rugby Football and American Football."

For an american football to be a spheroid, to start with it has to be elliptical in shape. The gridiron ball has two disticnt pointed ends and therefore it is not a prolate spheroid. Eno1 14:44, 22 April 2007 (UTC)

It's a prolate symmetric top. --Kkmurray (talk) 20:52, 14 May 2010 (UTC)

## The Gherkin

Just wondered if the Gherkin in London is prolate spheroid. If so, perhaps it could be added to the text as an example of this shape. — Preceding unsigned comment added by 83.249.219.131 (talk) 11:27, 9 January 2012 (UTC)