by Steve » Mon Mar 14, 2016 2:22 pm
My money is on this being a bot account.
But, for a "great" answer, it's pretty easy. It's roughly equal to the initial energy at the muzzle minus the velocity lost to friction of air resistance, with the lost energy partially converted to heat. If you consider the specific heat of the various components in the amalgam that is the bullet, and treat the jacket and the core as collocated solids, the friction heat will reduce the maximum yield strength of the materials until flow conditions are met, at which point the cross-sectional area will generally tend to increase. This is due to the considerably lower liquidus transition temperature of lead compared to copper alloys. Solids can withstand considerable shear stress before significant deformation occurs. Fluids are defined by their inability to withstand shearing forces. When you try to shove a fluid, it tends to flow away from the force. When it cannot, it applies pressure in all directions. This pressure if force over area, and when combined with the increased heat, can cause the petals of the hollow point to begin to blossom away from the lead core. This increase in diameter causes additional air resistance.
In practice, the ranges are so short and velocities fairly low enough that the projectiles generally strike their target or the ground before this significantly impacts the flight of the round or really opens up the cup.
However, if you can get the projectile to move really really fast with enough air resistance, you can actually force your projectile to fully convert to plasma. Which pretty much kills your range, but the math is impressive. Plus, plasma sets stuff on fire and / or burns through it. And if you have enough energy behind it, you can get a wave of air converted to plasma that is propagating conically out forward-away from your projectile sort of like how the Compton Effect causes directed energy weapons to be really really inefficient in an atmosphere.
Have fun running that generally correct yet entirely useless response through google translate.
Edit: find something that will soak 54 kilojoules of force instantaneously applied to a 2 in^2 area with less than 25mm of back face deformation and you are unlikely to run into anything that will defeat your armor. Unless you do something remarkably stupid, like piss off folks who own MBTs.
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