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Re: [Phys-l] Aristotelian thinking (WAS: buoyancy on a submerged pole)



Archemedean Thinking - an object submerged in a fluid will experience an upward force equal to the weight of fluid displaced.


At 12:58 PM -0500 11/5/10, John Clement wrote:
Actually, the buoyancy conception is a useful model, and the problem is
inappropriate application where it does not work. The model of things
wanting to rise is a separate idea from medieval times that motion is caused
by forces inherent in the object. The big trick is to understand that
buoyancy is an effect where the water is doing the pushing, and no water
under the object, the model does not apply.

I doubt that anyone on this list suffers from the medieval idea, but some do
have the concept of buoyancy as a force which is always pushing something
upward. They have to consider interactions, a free body diagram, and NTN.
It is true that teachers have from time unknown taught that things want to
do something, such as hot air wants to rise. Such teachers are thinking
Aristotelian and would often test at the concrete operational level. While
it is true that these conceptions lie in wait and bite you when you least
expect it, most people on this list are not concrete operational. I always
hesitate to say all because I have been surprised too often by people. The
traditional methods of teaching do not do a good job of helping people make
a coherent Newtonian model and to think at the formal operational level.