jjl wrote:
> Example is as follows:
>
> The breaking strength of a fiber is required to be at least 150 psi.
150 pounds per square inch? That is not only inconvenient to measure,
as it involves computing cross section as well as the tension under
which it breaks; it's also pretty pathetic for anything I'd classify as
a "fiber", let alone bother testing.
I'd guess cooked spaghetti (_al_dente_, not cooked to mush) might come
in a bit under that figure; just about any string would be a lot
stronger. As an experiment, I just rolled and twisted a 2-yarn cord out
of Kleenex, about 1/8" in diameter; while the length does not afford a
really good grip, I can't break it with my bare hands and would estimate
a lower bound on the tensile strength of 25 lbs. That's about 2000 psi
right there.
Ah, real-world examples...Reminds me of one in a locally-written high
school textbook that involved Anne [all problems in modern K12 textbooks
must contain a proper name] riding on a Ferris wheel with radius 6m that
went around once every 4 seconds. Quite a ride - the seats would have
been upside-down at the top!
-Robert Dawson
.
.
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