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Re: Theropod stance balance



It seems to me that your feet have further to travel
in the attempt to catch up to your falling mass
center... and more weight to move (bigger feet) and
"catch" (bigger body). Weight increases exponentially
with length... so assuming "stumbling stones" remain
proportional to height, I don't see time as a factor.

--- Martin Baeker <martin.baeker@tu-bs.de> wrote:
> > As a biped, I'm sceptical of the "don't fall"
> strategy
> > for (large) bipeds.  But you might be right, of
> > course. Good thing they had no beer. 
> 
> Some time ago, I did some simple calculation (at
> that time to understand 
> why small animals need faster metabolism than large
> ones) concerning 
> stumbling. Here is what I wrote back then:
> 
> "If you are not running on very smooth
> ground, you will have to adjust your movements to
> the stumbling stones you
> encounter, otherwise you will frequently land on
> your nose. Now the time
> you have to recover from stumbling or to adjust to
> uneven ground, is
> obviously proportional to the time you have until
> you belly hits
> the ground, i.e. until your center of mass has
> fallen a certain distance.
> This time scales like 
> 
> t ~ sqrt(l/g)"
> 
> with l being some measure of your length and g earth
> gravity's 
> acceleration. 
> 
> So if a human has about half a second to adjust his
> or her steps to uneven 
> ground, a T rex (with perhaps three to four times
> the leg length) 
> will have almost a full second to react, all other
> things being equal 
> (which they are not, I know). So although the
> injuries from falling may be 
> worse for a T rex, it will be easier for it to avoid
> them (unless 
> metabolic rate decreases faster than the time to
> recover increases).
> 
> Cheers,
> 
> Martin.
> 
> 
> 
>                    Priv.-Doz. Dr. Martin Bäker
>                    Institut für Werkstoffe
>                    Langer Kamp 8
>                    38106 Braunschweig
>                    Germany
>                    Tel.: 00-49-531-391-3073         
>             
>                    Fax   00-49-531-391-3058
>                    e-mail <martin.baeker@tu-bs.de> 
>