Stopped Bats and Rising Fastballs: .


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Thanks to J. J. Crisco & R. M. Greenwald Medicine & Science in Sports & Exercise 34(10): 1675-1684; Oct 2002. Corked Bats and Rising Fastballs: . Alan M. Nathan Department of Physics University of Illinois. Using Physics to Debunk Some Myths of Baseball September 23, 2006.
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On account of J. J. Crisco & R. M. Greenwald Medicine & Science in Sports & Exercise 34(10): 1675-1684; Oct 2002 Corked Bats and Rising Fastballs: Alan M. Nathan Department of Physics University of Illinois Using Physics to Debunk Some Myths of Baseball September 23, 2006

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Corked Bats and Rising Fastballs: Using Physics to Debunk Some Myths of Baseball October 27, 2004: the day the revile was broken

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References "Our objective is not to change the amusement but rather to comprehend it. "The physicist\'s model of the diversion must fit the amusement."

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References "The book is composed for the inquisitive layman… " "… numerous dubious claims about the diversion are tended to and… determined by this book."

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References Is this paradise? No, it\'s … . Iowa Dyersville, home of the Field of Dreams http://www.npl.uiuc.edu/~a-nathan/pob

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Outline How does a slugging stick function? The flight of a baseball. Leaving the no-turn zone. Assembling it all.

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Issues I Will Address What makes a difference more: pitch speed or bat speed? Is the ball "squeezed"? What/where is the "sweet spot"? Is plugging the bat successful? Does aluminum beat wood? Does a fastball rise? What\'s the arrangement with Denver? Can a curveball be hit more distant than a fastball?

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Champaign News-Gazette "You can watch a considerable measure by viewing" - Yogi Berra Easton Sports CE Composites

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When Ash Meets Cowhide A rough crash! constrains substantial (>8000 lbs!) ; time short (<1/1000 sec!) ball packs, stops, extends like a spring: motor vitality  potential vitality wasteful: loads of vitality disseminated bat draws back, vibrates bat pulls back, vibrates GOAL: expand batted ball speed ( BBS) BBS  105 mph, 30 o  d  400 ft each extra mph  ~5 ft

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What Determines BBS? pitch speed, bat speed, "impact proficiency" my exclusive recipe BBS = e v pitch + ( 1+e ) v bat average numbers: e = 0.2 1+e = 1.2 case: 90 + 70 gives 102 mph (~400") v bat matters considerably more than v pitch ! Every mph of bat speed worth ~6 ft Each mph of pitch speed worth ~1 ft

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What does e rely on upon? BBS = e v pitch + ( 1+e ) v bat 1. Weight and weight dispersion of bat Heavier bat more proficient bigger e; less backlash to bat Heavier bat has littler v bat (ordinarily) What is perfect bat weight? impact of bat weight on e is simple impact of bat weight on v bat harder

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Experiments to Determine v bat Use rapid video Measure reliance of v bat on … - bat weight W - "swing weight" or MOI Conclusion: MOI matters more than W Observation: Batters incline toward lighter bats—31-34 oz - control versus control

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Is There an Advantage to "Plugging" a Bat? In view of best exploratory information accessible: … for grand slam separate: no … for grand slam recurrence: possibly

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What does e rely on upon? 2. Bounciness of ball "coefficient of compensation" or COR 2 = bounce back ht/starting ht ~0.5 for baseball demo

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MLB specs Is the Baseball "Squeezed"? Is COR bigger than it used to be? Estimations with rapid gun COR=rebound speed/starting pace 1975 versus 2004 MLB rules permit ~ 10% scope of COR  35 ft 1975 and 2004 equivalent to few % No confirmation for squeezed ball

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What does e rely on upon? Affect area on bat: the "sweet spot" Minimize force to bat—at Center of Gravity Maximize bat speed—at tip Minimize vibrations which… sting! some of the time break the bat lessen COR  bring down BBS demos

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hubs CG The "Sweet Spot Zone" PC reproduction … which concurs with trials

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Vibrations and Broken Bats pitcher catcher motion picture

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Does Aluminum Outperform Wood? Aluminum has thin shell Less mass in barrel - bring down MOI, higher bat speed, simpler to control  - however less successful at exchanging vitality  - for some bats  scratchs off  simply like plugged wood bat "Circle modes" trampoline impact  "ping" demo

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The "Trampoline" Effect: A Simple Physical Picture Two springs commonly pack each other KE  PE  KE PE shared between "ball spring" and "bat spring" PE in ball for the most part scattered (~80%!) PE in bat for the most part reestablished Net impact: less general vitality disseminated ...and in this manner higher ball-bat COR … more "bob"— affirmed by test … and higher BBS Also found in golf, tennis, … demo

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Does Aluminum Outperform Wood? YES!

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Additional Remarks on e can be measured in the lab manage non-wood bats (NCAA, ASA, … ) "end conditions" don\'t make a difference Not even the player\'s hands!

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F Lift  F drag mg Forces on a Baseball in Flight Gravity Drag ("air resistance") Lift (or "Magnus") demo

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Effect of Drag and Lift on Trajectories F L (Magnus)  F d mg drag impact is tremendous lift impact is littler yet critical

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Some Effects of Drag Reduced separation on fly ball Reduction of pitched ball speed by ~10% Asymmetric direction: Total Distance  1.7 x remove at zenith Optimum grand slam edge ~30 o - 35 o

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F L (Magnus)  F d mg Some Effects of Lift Backspin makes ball rise "bounce" of fastball undercut balls: expanded separation, decreased ideal edge of homer Topspin makes ball drop "12-6" curveball topped balls plunge Breaking pitches because of turn Cutters, sliders, and so on

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F L (Magnus)  F d mg Does a Fastball Rise? Will a ball tossed evenly rise? Is there a net upward speeding up? Can Magnus compel surpass gravity? For this to happen… reverse-pivot must surpass 4000 rpm >25 upheavals not physically conceivable

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What\'s the Deal with Denver? High height, diminished gaseous tension 80% of ocean level Reduced drag Reduced lift Net impact: Fly balls travel ~5% more distant

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Oblique Collisions: Leaving the No-Spin Zone Oblique  f riction  turn Familiar Results: Balls hit to left/right break toward foul line Topspin gives dubious ricochets in infield Backspin keeps fly ball in air longer Tricky popups to infield demo

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Ball10 0 descending D = focus to-focus balance Bat 10 0 upward Undercutting the ball  reverse-pivot directions "vertical sweet spot"

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Putting it all Together: Can curveball be hit more remote than fastball? Bat-Ball Collision Dynamics A fastball will be hit quicker A curveball will be hit with more reverse-pivot

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Fastball with reverse-pivot Curveball: turn doesn\'t switch Curveball with topspin curveball can be hit with more reverse-pivot: WHY? Fastball: turn must switch Net impact: reverse-pivot bigger for curveball

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Can Curveball Travel Farther than Fastball? Bat-Ball Collision Dynamics A fastball will be hit speedier A curveball will be hit with more reverse-pivot Aerodynamics A ball hit quicker will travel more remote Backspin expands separate Which impact wins? Curveball, by a hair!

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Final Summary Physics of baseball is a fun use of essential (and not really fundamental) material science Check out my site on the off chance that you need to know more www.npl.uiuc.edu/~a-nathan/pob a-nathan@uiuc.edu Thanks for your consideration and go Red Sox!

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