Sorry folks, but in an idle moment during lunchtime I had to scratch around in
the back of my brain for my school math formulae to compare this steel dart and
the sparrow. I kept to "imperial" units of measure...
My results are that dropping the 2lb steel dart from 8-10 feet gives a terminal
velocity (after 0.75 seconds) at the helmet of about 24 ft/sec. That's a
kinetic energy of 0.5*mass*velocity-squared = 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)
best regds
Jez-the-ex-mathematician
Richard Keefer said
Many (many many) years ago I was involved in testing of lenses for motorcycle
goggles. As I recall, the test was a 2 lb (1 kg) steel dart with a blunt point
dropped from 8 or 10 feet directly into the lens supported by the frame with a
foam face behind
it. No part of the lens or dart could touch the face. I distinctly recall
thinking - NO WAY do I want to get hit that hard.
Looks like the test was pretty accurate.
Ric
----- Original Message -----
From: DAVDOU9211@xxxxxxx
To: olympus@xxxxxxxxxxxxxxx
Sent: Friday, August 17, 2001 12:29 AM
Subject: Re: [OM] Re: framing
. I encountered what I think was a sparrow at 110mph on I-25 north of
Denver. Nothing there
and then a speck, and then in less than the wink of an eye, BAM! Snaped my
head back, but nothing penetrated
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