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[Phys-L] Using soda bottles for experiments.

It was years ago on this list:  - an interesting thread on demonstrating the weight of an airmass by weighing a soda bottle before and after compressing the air inside.
It probably stuck in mind because I tried it at modest pressure, and another contributor took it to bursting point.
 So now, it sticks in mind that a cubic meter of air is 1.3 kg!

These days, we buy water in plastic bottles because the local water is close to a sulfite seam, useful for wall boards.
And I was tickled to learn that plastic memory is not just peculiar to irradiated polyolefin tubing.  It turns out that enthusiasts are reclaiming plastic soda bottles (which are a triumph of the ChemEng's craft - both light and strong, yet collapsible from cap to base with moderate hand force.) It appears that cutting a band out of a used soda bottle provides a very usable connector on (for example) broken chair legs. Once in place, the band is heated by a hot air gun ($12 HF!)  and shrinks to a sturdy support. I suppose I should have grasped that an object formed by heating and impressing plastic into bottle form, leaves a thermal shape memory of some kind.
Echoes of  the builder's art of testing concrete with a diamond coring drill, used  by geophysicists to core a rock and identify its magnetic orientation - a key component in supporting the theory of buoyant plates on Earth's surface last century.

Brian W