• Question: Why do eggs crack ?

    Asked by camel12 to Tom, Tim on 26 Jun 2012.
    • Photo: Tom Lister

      Tom Lister answered on 26 Jun 2012:

      rather than smash into dust? There are lines of particular weakness in the shell that break more easilt than the other bits.

    • Photo: Tim Stephens

      Tim Stephens answered on 26 Jun 2012:

      I don’t know what the structure of an eggshell is, whether it’s a crystal (where the atoms are all regularly arranged and joined together), or more like glass (where the atoms are not so tightly connected).

      If it’s a crystal, then once you start to break the bonds in a particular place (by hitting it against the edge of the frying pan, for instance), then the weakness will propagate along that row of bonds.

      If it’s more glass-like, then the weakness that you introduce when you crack it will propagate based on the stresses within the material. You can see this effect when you see people cutting glass. They score the glass along the line that they want it to break with a sharp tool and then bend the sheet, causing the imperfection on the surface to propagate through the material and produce the cut that they need.

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