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Name: Evelyn
Status: student
Age:  40s
Location: N/A
Country: N/A
Date: 2000-2001


Question:
What is a non-newtonian substance? Is this some fad that I've somehow been left out of?

I don't know about a "non-Newtonian substance" is in general, but a non-Newtonian fluid is one whose viscosity (resistance to flow) changes in response to some factor besides temperature. For example, a mixture of cornstarch in water flows like a regular liquid if you pour or stir it slowly, but if you stir it vigorously, it "sets" and acts more like a non-flowing solid until you stop stirring it. This is a phenomenon known as "shear thichening."

Richard E. Barrans Jr., Ph.D.
Assistant Director
PG Research Foundation, Darien, Illinois


A Newtonian substance behaves according to Isaac Newton's models of reality, Isaac Newton's Laws of motion. A non-Newtonian substance is extreme enough so as to require something such as relativity or quantum mechanics to describe how it acts. A substance made of gluons would qualify as non-Newtonian.

Kenneth Mellendorf


No Fad -- Not Left Out!!

A NEWTONIAN fluid is a fluid in which the rate of shear -- think of rate of shear as the motion of the body of fluid -- is proportional to the shear stress -- think of shear stress as the applied force. The reason for these rather abstract definitions is because there can be so many configurations of fluids and sources of force. The key is the proportionality of motion and force.

There are many kinds and combinations of non-Newtonian fluids. Some familiar examples are: WATER = newtonian. House paint = shear thinning. That is it is viscous when not stirred but flows smoothly on the brush with minimal "drag". Certain muds are shear thickening. You can run across them, but don't stop or you will sink in.

There is an enormous fascinating technology surrounding non-Newtonian behavior of fluids. I would suggest you try to find a copy of Surface Chemistry by Adamson in the library.

Vince Calder



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