1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

My projectile penetration equation (Help needed!)

  1. Feb 6, 2010 #1
    Right, so I've just created my Franken-Equation and it hungers for brains, as well as acceptance. Unfortunately for my monster, he was created by a man with only rudimentary knowledge of the nervous system and a budget consisting of earnings from his less than successful homemade mosquito repellent (consisting of naphthenic acid, palmitic acid, and gasoline.)

    Anyway, I've taken a number of hazardous leaps of faith in this equation, so please bear with me.

    Note: This equation assumes pure translational kinetic and no rotational kinetic energy with a conical tip.

    The final equation looks like this:

    x=penetration distance
    Z=resistance of armor to penetration (using only units in the equation to solve for the units of Z gave something akin to force that seems somewhat reasonable.)
    [tex]\theta[/tex]=complement of angle formed by penetrated surface and outer edge of projectile
    m=mass of projectile
    v=velocity of projectile immediately prior to impact

    So I guess the first and most deadly leap was equating kinetic energy with N[tex]\times[/tex]m. If this doesn't hold true the equation may tear at the seams and let the rabid radioactive monkeys out of the bag (there were supposed to be cats in the bag but due to a mixup at the factory, located conveniently next to the former Chernobyl power plant, the cats are now having lipstick and makeup tested on them.)
    I await your critique with bated breath.
    Last edited: Feb 6, 2010
  2. jcsd
  3. Feb 6, 2010 #2


    User Avatar
    Homework Helper

    Well, since you asked for critiques: you went waaay overboard with the metaphors :wink: Seriously, they're not helping.

    As for the actual equation: for one thing, your equation can't possibly be right because the units are inconsistent. On the left, you try to add a term with dimensions of length to a term with dimensions of area, which can't be done. Even besides that, I have no idea whether this equation is correct or not. It's impossible to say without doing some experiments to test its validity. If you explained how you came up with this, maybe we could offer some insight as to whether your procedure makes sense.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook