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发表于 2010-2-19 11:09
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How Does Corking a Bat Help a Hitter?
本帖来自:数学中国 作者: sea_star666 日期: 25 分钟前 您是本帖第87个浏览者
By Brendan I. KoernerPosted Wednesday, June 4, 2003, at 5:10 PM ET4 _$ p* E/ }! n$ @
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Chicago Cubs slugger Sammy Sosa is in hot water for using a corked bat in last night's game versus Tampa Bay. How does corking a bat help a hitter?# D t0 o+ d( i
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Corking a bat lightens the lumber, which in turn increases bat speedand, the conventional wisdom holds, hit distance. Corkers typicallydrill a hole at the end of the bat, hollow out the "sweet spot," andfill it with wine corks or Superballs.The hole is then sealed with a combination of sawdust and pine tar. Theresult is a bat that's several ounces lighter than advertised, thoughstill as long and thick as its heavier peers. A lighter bat, of course,is easier to whip through the strike zone.
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The theoretical edgeseems infinitesimal. Assume a corker reduces his bat's weight by 1.5ounces. An average major league pitch travels from the pitcher's handto the plate in a hair under half a second. The corked bat will givethe hitter an additional five-thousandths of a second to see the pitch,judge it, and get the bat head moving through the strike zone.
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Aquicker bat may help a struggling hitter catch up with pitches, but itactually reduces his ability to smack long drives. The primary equationthat determines a batted ball's distance is p = mv, where "p" is momentum, "m" is mass, and "v"is velocity. Though a corked bat will travel at a greater velocity, thetail-off in weight lessens the mass. As a result, sluggers like Sosawill actually see the length of their moon shots decrease. In his book The Physics of Baseball, Yale physicist Robert K. Adair estimated that a corked bat will shave about a yard off a 400-foot tater.
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Morelikely to benefit, then, are slap hitters who specialize in singles.But the advantage is more psychological than anything else—a corked batis essentially a placebo for hitters on the skids. They also splintermore readily, which makes catching the cheaters a lot easier. Ratherthan risk long suspensions, Adair advises, players should opt forlighter bats, perhaps by using a lighter grain of wood. Or they canjust choke up three-quarters of an inch, which produces the same uptickin bat speed as corking.Bonus Explainer:Surprisingly, the same major league baseball rules that outlaw corkingmake no mention of minimum or maximum bat weights, although there's amaximum length of 42 inches and a maximum diameter of 2.75 inches. Theearliest set of codified rules for professionals, published in 1857,recommended bats that weighed up to 48 ounces. Today, given theabundance of pitchers who throw 95-mph cheese, players prefer muchlighter bats; the current average weight is about 33 ounces.2 b% {$ l# ]2 u ?" O+ o$ |
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http://www.slate.com/id/2083972/ |
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