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[PSUBS-MAILIST] Eggshell and pressure
At 23:34 3.6.2003 -0700, you wrote:
>I came across this searching another subject.
>"the crush depth of an egg" So far I came up
>with zip, except for a lot of recipes for omelettes
>and other egg dishes [ and some agriculture reports].
Weird. I was looking into this for a friend of mine working
in biology lab in university.
http://aci.mta.ca/TheUmbrella/Physics/P3401/Investigations/EggBreakACR.html
In this page was found out that egg breaks at approximately 5kg's
point load (10 lbs). This corresponds to 1.1 MN/m^2 pressure
1.1 MN/m^2 = 11 bar = 110 meters of fresh water (360 ft)
>What prompted Bushnell to design his sub in this shape? Was
>he pondering an egg while eating breakfast? Was he familiar
>with that parlor trick [ and how old is that parlor trick? ] :-)
I'd bet the design comes from a barrel with a extension for weight
(keel) to keep it upright. But we'll propably never know ...
>The arch or dome shape is a geometric structure used throughout
>history evident in Greek and Roman architecture and civil engineering
>and the cathedrals in the Middle Ages.
>
>I think geometry and structure figures in over thickness of the shell?
>The shell of a nautilus is a few millimeters thick yet can withstand
>tremendous pressures. An egg shell is nearly a perfect ellipsoid
>with no seams.
The perfect pressure vessel shape is still the ball.
Egg has other functions that affect its shape.
- It has to be taken out of the chicken (or lizard or ...)
without harming the "host".
- Pressure on the egg if <Insert a tecnical term for sitting on top of eggs>
by a parent is not equal on all sides so you (or the chicken) can optimize
shape and local wall thickness to save on material.
- Birds nesting on bare smooth rocks have very connical shaped eggs to
keep them from rolling far from nest.
- (some) Dinosaurs had extremely wedge shaped eggs that fitted together in
the nest
so that only the broad ends of the eggs would be visible. Reason is
unknown, but
could be about weight distribution and keeping the eggs warm.
>So...does anyone know the crush depth of an egg?
Empty, boiled or raw ;)
110m would propably be the crush depth of an empty egg.
Because most of the load on the egg when using point load
is affecting via the shell it self.
How did chickens learn to pressure compensate a complex thin walled
pressure vessel with coagulating proteins.
They are _way_ ahead of us ;)
Jari Siikarla