here goes, another one of those noisy argumentative Aussies... :)
very blunt steel dart. contact area maybe 0.1" across = 0.008 sq in.
terminal spoggy (sorry, sparrow for the non Adelaideans!) 1 to 1-1/2 sq in.
steel dart: 576/.008 = 72,000 eu/sqin
spoggy: 814 eu/sqin
I think this is the penetrative force used to test the lexan with the
dart. I guess it's the 'ouch, my neck' energy dump value that's a
problem here though!
It reminds me of a story related to me by a friend who hit a sheep on a
'bike at speed on a country road, he likened it to hitting a bag of
water... he managed to keep the 'bike on 2 wheels & stop!
DavidT
Adelaide, South Australia
> At 12:26 PM +0200 8/17/01, Jez.Cunningham@xxxxxxxxxx wrote:
> >compare this steel dart and the sparrow. I kept to "imperial" units
> >
> >My results are that dropping the 2lb steel dart from 8-10 feet gives
> > 576 (what are the units?)
> >
> >For the sparrow, say 1 ounce, at terminal velocity of 110mph
> >(terminal for the sparrow!) the energy comes out at 5162 energy
> >units!
> >
> >ALMOST TEN TIMES WORSE THAN THE LAB TEST!
> >Sounds to me like you were lucky! (Not so lucky for the sparrow)
> >Jez-the-ex-mathematician
>
> I think this ain't right. I get about 161 fps, which squares to
> 26,028, divide by 32 for the difference in mass and you get about
> 814 energy units. If it had been a grackle, though...
>
> paul the ex-physicist
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