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Gelatin Displacement
name Sarah
The physics class at Fatima H.S. would like to find out if gelatin has an
accepted moduli. That is, is there a standard displacement of the surface of
a brick of Jello if a surface stress is applied?
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Hello,
Gelatin is actually a protein, often extracted from animal skin, bone, and
connective tissues (unknown to some vegetarians). Gelatin can also be
obtained from seaweed but it is more expensive and is not normally used in
food.
When mixed with certain liquids, gelatin proteins trap the liquid in their
midst and when the mixture is cooled below some temperature, the result is
a glassy substance also referred to as gelatin. What we discuss here is
this gelatin.
I do not know, from an engineering standpoint, how gelatin is classified
. My engineering books do not seem to cover it. Gelatin is not an
elastomer because it is not made of polymers. It is a colloidal, however.
Gelatin has a modulus, just as rubber has. But unlike many other substances
(e.g., metals), its modulus would have a strong velocity dependency. This
means that you get a different stress-strain curve (whose slope is defined
as the Young's modulus) depending on the rate of strain.
Actually, gelatin is a great substance to work with and learn from in the
class room. It is cheap, safe, and very small forces are needed to move it
around and measure (that is, it has a low modulus). You can measure its
modulus of elasticity using standard techniques.
I am sure you can find more information on this than I can provide, but
please let me know if you found information on its classification and
properties.
Good luck,
AK
Dr. Ali Khounsary
Advanced Photon Source
Argonne National Laboratory
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