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# Spinning egg test

Friction, Eh? Let's see.
 (+3) [vote for, against]

A few years back, a 6 month mathematical analysis of a spinning egg was completed. The conclusion was that the friction between egg and table top was responsible for putting the egg up on end.
Not only is the centre of gravity higher, but the egg spins faster because it pulls itself into a tighter radius. Both are counter intuitive.

Could friction really be responsible?

I propose that when an adventurous halfbaker takes to the air in G-Force One with simulated zero gravity, then they take a packed lunch which shall include one boiled egg.

Then on the way down, spin the egg -mid cockpit- and report the findings.

 — Ling, Feb 14 2006

Take an egg for a spin http://www.explorat.../activity-spin.html
The science [Ling, Feb 14 2006]

G-Force One http://www.nogravity.com/airplane.htm
Surprisingly clean interior [Ling, Feb 14 2006]

//it pulls itself into a tighter radius//like an ice skater?
 — po, Feb 14 2006

I'm going to try this - but how do you actually get inside the egg - you didn't explain that part very well? +
 — xenzag, Feb 14 2006



 — po, Feb 14 2006

 I don't see how zero-G will help you test this. As boysparks suggests, what you need to explore is zero-friction conditions - spin the egg on rough and smooth surfaces, and see how the effect varies.

You could even make a magnetic egg and spin it on a bed of air, to test near-frictionless conditions.
 — DrCurry, Feb 14 2006

Testing the friction idea on the kitchen table? That's so very...down to earth.
I just had a thought, and I don't have a handy hard-boiled egg: does the egg always spin up onto the same end? Is it related to whether it is spun clockwise or anti-clockwise?
 — Ling, Feb 15 2006

 That's a similar explanation as with the mathematical proof.

 I tried to think of it this way: The egg initially spins around one axis. As it does so, the shape of the egg causes the egg to start to rotate around its axis of symmetry: it tries to roll. As the roll speed increases, the egg experiences a gyroscopic effect because the high roll speed is being asked to spin around a different axis. This generates a precessional force which tilts the egg to the vertical orientation.

 So, the role of friction is indirect, because it makes the egg roll. But the roll generates the gyroscopic force to tilt the egg.

 — Ling, Feb 15 2006

The precessional model should make the egg stand on its pointy end. Anyone with an egg?
 — spidermother, Feb 15 2006

I always preferred Christopher Columbus' method for getting an egg to stand on its end.
 — DrCurry, Feb 15 2006