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- Newsgroups: sci.military
- Path: sparky!uunet!zaphod.mps.ohio-state.edu!rpi!psinntp!psinntp!ncrlnk!ciss!law7!military
- From: ultra!norm@ames.arc.nasa.gov (Norm Finn)
- Subject: Re: RPG Combat Rules & Reality
- Message-ID: <Bxyv09.Fpz@law7.DaytonOH.NCR.COM>
- Sender: military@law7.DaytonOH.NCR.COM (Sci.Military Login)
- Organization: Ultra Network Technologies
- References: <BxM629.54s@law7.DaytonOH.NCR.COM> <Bxq1G2.At@law7.DaytonOH.NCR.COM> <BxtK1y.1Ay@law7.DaytonOH.NCR.COM> <BxvFr7.99y@law7.DaytonOH.NCR.COM>
- Date: Thu, 19 Nov 1992 14:02:33 GMT
- Approved: military@law7.daytonoh.ncr.com
- Lines: 63
-
-
- From ultra!norm@ames.arc.nasa.gov (Norm Finn)
-
- In article <BxvFr7.99y@law7.DaytonOH.NCR.COM> HADCRJAM@admin.uh.edu (MILLER, JIMMY A.) writes:
- >
- >> >Modern jackets/vests are fairly effective, but one thing most games ignore is
- >> >kinetic energy. Sure, so you got DAMN lucky and the .44 didn't punch through
- >>
- >> I've always wondered about this. The person *shooting* the .44 had to
- >> accept just as much momentum when shooting as the bullet imparts to the
- >> recipient.
- >>
- >> It seems like if the vest distributes this over a wide enough area you
- >> could void any damage at all.
- >
- > Well, yes but this is pretty tricky, I would think. And in answer to the
- >question concerning about the shooter receiving momentum, consider that the
- >shooter has shock absorbtion available (stocks, gas bleeds, the motion of the
- >body or hands backwards, momentum absorbed by the mass of the weapon itself,
- >etc.). The target has to absorb all that kinetic force on a spot somewhat
- >smaller than a dime...
-
- Let's get back to basic physics, guys. The explosion of the powder
- imparts equal momentum to 1) the bullet and blow-by gasses in one
- direction, and 2) the gun in the other direction. The bullet gets most
- of the momentum in its direction. Now, momentum (p) = mass (m) *
- velocity (v). If the bullet is 1/50th the weight of the gun, it gets 50
- times the velocity.
-
- What about energy? Kinetic energy (e) = 1/2 * m * (v squared). So if
- the bullet gets 50 times the velocity, it gets 2500 times the energy.
- That is, most all the energy of the power explosion is converted
- into the kinetic energy of the bullet. (OK, OK, there is some angular
- momentum and energy, too, because the bullet is spun up by the rifling
- grooves, and a big *bang*, etc., but let's stick to the main factors.)
-
- We'll ignore the energy and momentum the bullet loses to the air during
- its passage to the target, and worry about the target. The inelastic
- collision at the target transfers the momentum of the bullet to the
- momentum of the bullet+target mass. It is equal to the momentum given
- the gun when it was fired. It doesn't amount to a hill of beans.
-
- The energy, however, is very important to the target. The kinetic
- energy of the bullet is dissipated upon the bullet and the target by
- being transformed into heat, shock waves, ripping, tearing, and general
- mayhem. If the target is kevlar armor, the energy is dissipated into
- the ripping and heating of the kevlar, shock waves through the vest and
- person, etc.
-
- You can think of a gun as a reasonably efficient energy transmission
- device. It transmits the energy of an explosion to a target. It also
- transmits momentum, but that's not important.
-
- (Does this come up often enough for the FAQ file? I've seen similar
- questions often enough.)
-
- [mod note -- It might be in the rec.guns FAQ ]
- --
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