Re: PHYSICS: Getting knocked on your ass (was Re: TERRORISM: looking forsolutions)

From: hal@finney.org
Date: Fri Sep 14 2001 - 19:58:20 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
> >
> > Which means there is enough energy, leaving the muzzle, for the bullet
> > to move 941 pounds one foot in distance. A person who is 157 pounds will
> > be moved 6 feet: i.e. knocked on their asses.
>
> For the irony impaired on this list, I should note that Mike Lorrey is
> JOKING.

I'm not sure why you say that. He's wrong, but he doesn't seem to be
joking. 941 foot-pounds is enough energy to raise a 157 pound person
by 6 feet, but the problem is you can't turn the energy directly into
motion like that. Most of it will be dissipated as heat if the bullet
hits something that stops it like a Kevlar vest.

What you need to do is to calculate the momentum, as someone else
pointed out. The bullet will give the man a velocity of about 1/4 foot
per second, enough to rock him back, maybe lose his balance, but not
necessarily knock him off his feet.

Hal



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