Doug Jones wrote:
>
> 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.
And what happens when the bullet hits a kevlar vest? Every time I've
seen someone get hit with a vest on, if they weren't leaning into it,
expecting the hit, they get knocked on their asses (though that depends
on the particular round, of course).
This archive was generated by hypermail 2b30 : Fri Oct 12 2001 - 14:40:46 MDT