From: Robert Coyote (coyyote@hotmail.com)
Date: Fri Sep 14 2001 - 17:14:33 MDT
As an example in Momentum
Cartridge 44 Magnum
Caliber in Inches 0.43
Bullet Weight in grains 240
Muzzle Velocity in feet per second 1348
Muzzle Energy in foot-pounds 941
Momentum in Power Factor (grain-feet per 1000 seconds) 324
----- Original Message -----
From: "Doug Jones" <djones@xcor.com>
To: <extropians@extropy.org>
Sent: Friday, September 14, 2001 2:53 PM
Subject: Re: PHYSICS: Getting knocked on your ass (was Re: TERRORISM:
looking forsolutions)
> James Rogers wrote:
> >
> > Part of the problem is that you are confusing energy with power. A
punch
> > doesn't have a lot of power but it does have lots of energy. A pistol
> > bullet has a moderate amount of power, but minimal energy. Energy is
what
> > knocks you on your ass, power is how its delivered.
>
> I'm afraid you're mistaken, James. The terms you need are energy
> (0.5*mv^2) and momentum (mv). A fist carries quite a bit of momentum
> due to its mass, but little energy due to the low velocity. Bullets are
> low mass, high velocity. For example (rough guesstimates):
>
> mass velocity momentum energy
> Fist 1 kg 10 m/s 10 kg-m/s 50 J
> Bullet .003 kg 500 m/s 1.5 kg-m/s 375 J
>
> Thus a blow with a fist or foot is likely to impart substantial momentum
> to the target, while a bullet penetrates and tears it while not causing
> much movement.
>
> --
> Doug Jones, Rocket Plumber
> XCOR Aerospace
>
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