Re: [Phys-l] Another tire question

[Brian Whatcott <betwys1@sbcglobal.net>]

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!