Re: long and short

[Roger Haar <haar@PHYSICS.ARIZONA.EDU>]

Hi,
        It may be that the original comment was about the impact of the head on
the ground.  If one assumes that the body falls as a rigid rod, (and maybe that
on impact the head acts as loosely connected to the rest of the body,)  I
suspect that the impact velocity might increase quite a bit, and thus the
energy would also go up quickly.

Thanks
Roger haar

Tim Folkerts wrote:

> > In the November Scientific American on p. 28, Thomas Samaras is referenced
> as claiming
> > that a person 20% taller than another, in falling over will hit the ground
> with 210% more
> > kinetic energy than the shorter person.
>
> Actually, assuming a slight misstatement of the result and a simple but
> questionable assumption, it is fairly straight forward
>
> 20% taller => 20% bigger all around  [ i.e. the questionable assumption]
>            => (1.2x taller) * (1.2x wider) * (1.2x thicker) = 1.78 times
> heavier
>
> Also, the CM is 1.2 times higher, so PE = (1.78m) g (1.2h) = 2.07 mgh
>
> So, if  KE(final) = PE(initial) we have ~210% times the original KE {which
> is NOT 210% more KE, it's just 110% more}.
>
> Tim Folkerts