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The Range
Handgun Discussion
Terminal Ballistics from the Morgue
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<blockquote data-quote="Rod Snell" data-source="post: 1615913" data-attributes="member: 796"><p>Just a comment from the ol' physics prof:</p><p></p><p>Even assuming the two bullets lose speed at the same rate (they won't, sectional density is different),</p><p>that does NOT mean KE will decrease at the same rate because KE is proportional to the SQUARE of velocity. <strong>A bullet that loses half its speed loses 3/4 of the KE.</strong></p><p></p><p>Unfortunately, the drag on a projectile is also proportional to the SQUARE of speed, so the faster bullet slows down % higher than the one that starts slower. Look at a ballistics table for .270 rifle, for example, and while a 100gr bullet starts much faster, at distance, the 140gr bullet is going faster then the 100 gr and has much more energy.</p><p>At 25 feet, the relative loss is much smaller, but easily calculated from a ballistics chart.</p><p></p><p>The other problem is tht the effect of a bullet on tissue is not solely determined by the KE of the projectile, but is heavily influenced by the frontal area and sectional density. Of course, the trump card is where the bullet hits.</p><p></p><p>PS: The reason the numbers in the KE calculaions above look so large is the M stands for MASS, and the English unit of mass is the SLUG (approx 32#)</p><p></p><p>This handy calculator takes care of the units conversion for you:</p><p><a href="http://www.handloads.com/calc/quick.asp" target="_blank">http://www.handloads.com/calc/quick.asp</a></p></blockquote><p></p>
[QUOTE="Rod Snell, post: 1615913, member: 796"] Just a comment from the ol' physics prof: Even assuming the two bullets lose speed at the same rate (they won't, sectional density is different), that does NOT mean KE will decrease at the same rate because KE is proportional to the SQUARE of velocity. [B]A bullet that loses half its speed loses 3/4 of the KE.[/B] Unfortunately, the drag on a projectile is also proportional to the SQUARE of speed, so the faster bullet slows down % higher than the one that starts slower. Look at a ballistics table for .270 rifle, for example, and while a 100gr bullet starts much faster, at distance, the 140gr bullet is going faster then the 100 gr and has much more energy. At 25 feet, the relative loss is much smaller, but easily calculated from a ballistics chart. The other problem is tht the effect of a bullet on tissue is not solely determined by the KE of the projectile, but is heavily influenced by the frontal area and sectional density. Of course, the trump card is where the bullet hits. PS: The reason the numbers in the KE calculaions above look so large is the M stands for MASS, and the English unit of mass is the SLUG (approx 32#) This handy calculator takes care of the units conversion for you: [url]http://www.handloads.com/calc/quick.asp[/url] [/QUOTE]
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