Experimental techniques in nuclear and particle physics (part 3)
My day job… experimental nuclear/particle physics
description
Transcript of My day job… experimental nuclear/particle physics
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Hitting Home Runs:How a Physicist Thinks About Baseball
Alan M. NathanUniversity of Illinois at Urbana-Champaign
http://www.npl.uiuc.edu/~a-nathan/pob
My day job… experimental nuclear/particle physics
high-speed collisions between subatomic particles
Nights and weekends... physics of baseball
high-speed collision between baseball and bat
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Hitting the Baseball
“...the most difficult thing in sports”
--Ted Williams
BA: .344SA: .634OBP: .483HR: 521
#521, September 28, 1960 Aerodynamics of ball The ball-bat collision
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Here’s Why…..(Courtesy of Robert K. Adair)
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Trivia Timeout Rogers Hornsby is one of only two players
to have won the Triple Crown twice. Who is the other player?
A) Hank Aaron
B) Mickey Mantle
C) Carl Yastrzemski
D) Ted Williamscorrect
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The Ball-Bat Collision
forces large (>8000 lbs!) time is short (<1/1000 sec!) ball compresses, stops, expands bat compresses ball….ball bends bat hands don’t matter! to hit a home run, you need...
large hit ball speed
the right take-off angle
backspin
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Trivia TimeoutWho is standing behind Don
Larsen?
A) Bobby Richardson
B) Tony Kubek
C) Billy Martin
D) Yogi Berra
Don Larsen, 1956 World Series
Last pitch of perfect game
correct
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What Does Hit Ball Speed Depend On?
Pitched ball speed & bat swing speed
bat speed matters much morevhit = 0.2 vball + 1.2 vbat
Weight and weight distribution of bat what is ideal bat weight?
Bounciness of ball is it “juiced”?
Impact location along bat “sweet spot”
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The Sweet Spot
60
70
80
90
100
2 3 4 5 6 7 8 9distance from knob (inches)
Hit Ball Speed (MPH)
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Who is this guy and what was his number?
Trivia Timeout
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Wood versus Aluminum
Thin shell …. Lighter CG closer to hands…easier to swing fatter barrel, thinner handle “trampoline” effect
golf driverstennis racketscorked bats?
Net result:
higher batted ball speed
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Trivia Timeout
Who is standing behind Don Larsen?
A) Bobby Richardson
B) Tony Kubek
C) Billy Martin
D) Yogi Berra
Don Larsen, 1956 World Series
Last pitch of perfect game
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Aerodynamics of Ball in Flight
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The Flight of the BallReal Baseball vs. Physics 101 Baseball
Role of Drag
Role of Spin
Atmospheric conditionsTemperatureHumidityAltitudeAir pressureWind
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Spin on the Hit Ball
Friction induces spin for oblique collisions
Spin => Magnus force
Results
Balls hit to left/right break toward foul line
Backspin keeps fly ball in air longer
Topspin gives tricky bounces in infield
Pop fouls behind the plate curve back toward field
batball
topspin ==>F down backspin==>F up
sidespin ==> hook
bat
ball
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The Home Run Swing
• Ball arrives on 10o downward trajectory
• Big Mac swings up at 10o-15o
• Undercuts ball by 1”-1.25”
• Ball takes off at 35o with lots of backspin
The optimum home run swing!
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Who is this guy?
A) Joe Torre
B) Don Zimmer
C) Lou Skizas
D) Roger Maris
Trivia Timeout
correct
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Summary
Lots of physics in baseball
Knowledge of physics helps understanding
of game
And it’s fun too….