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Re: [Phys-l] Another tire question



Are physicists those who want to understand and know
everything but can not ?


--- Brian Whatcott <betwys1@sbcglobal.net> wrote:

At 09:50 PM 11/7/2007, Mike E., you wrote:
..
But the strange thing is, both upper and lower
spokes take a share
in supporting my weight. How can that possibly
be?

It can't be. This is a false statement. The lower
spokes are pulling down,
not pushing up.

Opposing spokes are in tension. When an
upper spoke sees
greater tension, a lower spoke is also seeing
reduced tension.

Yes. You said it. The lower spokes are still in
tension, although reduced.
...
Michael D. Edmiston, Ph.D.


Hmmm... I see I am not dislodging you from the upper
half support
position, Mike. I'll offer one more extreme case
to illustrate,
then leave the topic on its merits.

Let me select a tire of extraordinary wall strength,
but great flexibility.
Let me inflate this tire so hard, that regular tests
of deflection
and load bearing cannot distinguish it from a wheel
made entirely of steel.

You might think of this as the limit of high
inflation.
An engineer or physicist could hardly be faulted
for measuring
the load bearing contribution of the tire walls in
the lower half,
is that not the case?

And at the other inflation limit, a flat tire
demonstrably supports
the entire load on the lower portion of the tire.

You already concur that a (lower) half tire can
support weight, but
you curiously spring to a "this is a balloon"
explanation. Yes, it is!

I rest.....


Brian Whatcott Altus OK Eureka!

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