Eggs-break 'em if you can
![[Do Science] Bet you can’t break it this way.](egg-pressure.gif) Q: At what average water pressure does a chicken egg fail? --T.J. Senter, Pass Christian, Mississippi
A: "...you first have to prove that they do fail under hydrostatic (water) pressure," says Julian FV Vincent,
biomimetics professor at Bath University in Bath, England. (Biomimetics is the business of taking ideas in
nature and using them in engineering.)
[Do Science] Bet you can't break it this way.
Your question stipulates that we squeeze the egg with a pressure applied evenly in all directions. Under that loading, the egg is as strong
as the 3-dimensional arch that it is. It, a ceramic material like brick or concrete, can take enormous pressures without cracking.
"Consider a brick sitting at the bottom of a sky-scraper. It is supporting the entire weight of a column of bricks as high as the skyscraper
itself!" Says Vincent.
The only characteristic of an egg that might cause it to fail under a hydrostatic load is its small air pocket. The liquid contents of the egg
are essentially incompressible but the air pocket can give. Then the egg might deform locally over the air pocket and break.
Try it. Place an egg in your hand. Make sure you aren't wearing a ring. Slowly curl your fingers around the egg and start squeezing,
evenly. Be careful you don't dig in your fingertips and keep the pressure even. This procedure approximates applying a hydrostatic
pressure. I bet you can't break the egg. Put a ring on and you can, easily, as you deform the egg locally.
(Answered by April Holladay, science correspondent, November 28, 2001)
Further Surfing:
Do Science: Breaking eggs, the hard way
http://www.doscience.com/act_archive/home_activities/eggcitement/
U of Manchester: Average fracture stress of chicken eggshells
http://www.umist.ac.uk/MatSci/rip/profiles/academic/ke.htm
(Answered
November 28, 2001)
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