corked bats, humidors, and steroids: the physics of ... · corked bats, humidors, and steroids: the...
TRANSCRIPT
![Page 1: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/1.jpg)
1
Corked Bats, Humidors, and Steroids:The Physics of Cheating in Baseball
October 29, 2011Alan Nathan
![Page 2: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/2.jpg)
2
News Flash
![Page 3: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/3.jpg)
3
A great book to read….
“Our goal is not to reform the game but to understand it.”
![Page 4: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/4.jpg)
4
A more advanced book…
![Page 5: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/5.jpg)
5
…and if you really want a challenge
American Journal of Physics, June 2011
![Page 6: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/6.jpg)
6
“You can observe a lot by watching”
Collision time short (1 ms)
⇒ forces large (8000 lbs)
Collision is very inefficient
Bat slows down
Champaign News-Gazette
![Page 7: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/7.jpg)
7
What Determines batted ball speed (BBS)?
• pitch speed
• bat speed
• “collision efficiency”
![Page 8: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/8.jpg)
8
Baseball Quiz:
For longest fly ball, what matters more?1. pitch speed2. bat speed
![Page 9: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/9.jpg)
9
Baseball Quiz:
For longest fly ball, what matters more?1. pitch speed2. bat speed
Each additional mph of bat/pitch speed is worth 6/1 ft.
![Page 10: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/10.jpg)
10
What Determines BBS?
• pitch speed
• bat speed
• “collision efficiency”
• collision efficiency depends on…– “coefficient of restitution”– weight of bat
• bat speed depends on– weight of bat
![Page 11: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/11.jpg)
11
Corking the Bat
• Corking the bat…– increases bat speed
– decreases collision efficiency
• Which one “wins”?
![Page 12: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/12.jpg)
12
Is There an Advantage to “Corking” a Bat?
Based on best experimental data available:
for home run distance: no
for “frequency of good contact”: possibly
![Page 13: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/13.jpg)
13
What about steroids?
Steroids → added muscle → higher bat speed → higher batted ball speed →longer fly balls → more home runs
Some estimates:10% increase in muscle mass
→ 50% more home runs!!!
![Page 14: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/14.jpg)
14
Thanks to Roger Tobin
0
0.0025
0.005
0 100 200 300 400 500
Range (feet)
Pro
bab
ility
(p
er f
t)
Home Run Threshold
10%
14.9%
baseline
Bat speed 3% higher
![Page 15: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/15.jpg)
15
What Determines BBS?
• collision efficiency depends on…– “coefficient of restitution”– weight of bat
![Page 16: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/16.jpg)
16
Coefficient of Restitution (COR)
“Bounciness” of ball
– ~1/2 for baseball
• Bounces to ¼ of initial height
– bat matters also
demo
![Page 17: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/17.jpg)
17
Ways to cheat involving COR• Sneak in a superball or “sad” ball
400 ft → 650 ft ! 400 ft → 200 ft !
• Store at higher/lower temperature70o → 35o ⇒ 12 ft reduction70o → 105o ⇒ 12 ft increase
• Store at higher/lower relative humidity– more on this later
• mess around with the bat– ball-bat COR (BBCOR)
![Page 18: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/18.jpg)
18
Contribution of Bat to COR
“sweet spot” outside
![Page 19: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/19.jpg)
19
Vibrations, BBCOR, and the “Sweet Spot”
Evib
vf
e
+vibrations minimized
COR maximized
BBS maximized
best “feel”
0.1
0.2
0.3
0.4
0.5
0.6
0
10
20
30
40
50
0 5 10 15
BB
CO
R
vibr
atio
n fr
actio
n
distance from tip (inches)
Ball-Bat COR
vibrational energy
1234nodes
demos
![Page 20: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/20.jpg)
20
YouTube
How does weight & strength of batter contribute to collision?
Suppose Albert Pujols and Albert Einstein both swing the bat at the same speedand make the same good contact. Who will hit the ball harder?
Or do they both hit the ball the same?
![Page 21: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/21.jpg)
21
Hollow Bats and the “Trampoline” Effect:
demo
![Page 22: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/22.jpg)
22
Quiz (Tennis)To get higher speed on serve….
1. Tighten the strings2. Loosen the strings3. The strings don’t matter
![Page 23: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/23.jpg)
23
Quiz (Tennis)To get higher speed on serve….
1. Tighten the strings2. Loosen the strings3. The strings don’t matter
![Page 24: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/24.jpg)
24
Cheating and Hollow Bats• Shaving aluminum bats
– Thinner wall improves trampoline effect
• Rolling composite bats– Tiny cracks improve trampoline effect
These types of illegal modifications to bat can result in a large increase in fly ball distance (>35 ft!)
![Page 25: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/25.jpg)
25
![Page 26: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/26.jpg)
26
What is the optimum launch angle for a home run?
1. 40o
2. 30o
3. 20o
4. 10o
Baseball Quiz:
![Page 27: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/27.jpg)
27
What is the optimum launch angle for a home run?
1. 40o
2. 30o
3. 20o
4. 10o
Baseball Quiz:
![Page 28: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/28.jpg)
28
Coors Field in Denver:What’s Up With That?!
• High altitude, reduced air density –80% of sea level–Reduced air drag
• Fly balls carry farther• How much farther?• What does “carry” mean?
distance/distance-in-vacuum
![Page 29: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/29.jpg)
29
Analysis of 4354 HR from 2009
Denver: 6.5% or 26 ft
Cleveland Yankee Stadium
![Page 30: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/30.jpg)
30
Baseball Quiz:
What is the optimum launch angle for a base hit?
1. 40o
2. 30o
3. 20o
4. 10o
![Page 31: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/31.jpg)
31
Baseball Quiz:
What is the optimum launch angle for a base hit?
1. 40o
2. 30o
3. 20o
4. 10o
![Page 32: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/32.jpg)
32
Home Runs and Humidors
• Coors Field in Denver:– Pre-humidor (1995-2001): 3.20 HR/game
– Post-humidor (2002-1020): 2.39 HR/game– 25% reduction
• Can we account for reduction?• What if humidor were used in Phoenix?
![Page 33: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/33.jpg)
33
So, where’s the cheating?
![Page 34: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/34.jpg)
34
Home Runs and Humidors
• Measure ball COR at different RH– From 30% to 50%, COR decrease by 3.7%– Measurements @ WSU (Lloyd Smith)
• Physics + ball-bat collision model– Batted ball speed (BBS) reduced by 2.8 mph
• Hittracker+HITf/x– We know landing point, distance/height of nearest
fence for every home run– Calculate new trajectory with reduced BBS
• Mean HR distance reduced by 13 ft
– Does ball make it over the fence?
![Page 35: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/35.jpg)
35
Home Runs and Humidors
• The result:27 ± 4 % calculated25% actual (!)
![Page 36: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/36.jpg)
36
What about Arizona D-Backs?
%
%
![Page 37: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/37.jpg)
37
Trivia Timeout: Who is this guy?
![Page 38: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/38.jpg)
38
Trivia Timeout: Who is this guy?
Career HR/K1. Joe Dimaggio 361/3692. Lefty O’Doul3. Yogi Berra4. Lou Skizas 30/37
Urbana’s own Dr. Lou Skizas
![Page 39: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/39.jpg)
39
Game 1, 2011 WS
![Page 40: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/40.jpg)
40
1 2
3 4
5 6
![Page 41: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/41.jpg)
41
![Page 42: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/42.jpg)
42
The George Brett Pine Tar Incident
![Page 43: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/43.jpg)
43
The George Brett Pine Tar Incident
• So what’s the deal?– Pine tar increases friction between
ball and bat– Friction is used to put backspin on
batted ball• Increases distance• YouTube
• But careful investigation shows– Already enough friction– More doesn’t help
• Cooler heads prevailed– Umpire was overruled
![Page 44: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/44.jpg)
44
And finally...the pitcher• The break of a “normal” pitch• Spitters and grease balls• Scuff balls• YouTube video
![Page 45: Corked Bats, Humidors, and Steroids: The Physics of ... · Corked Bats, Humidors, and Steroids: The Physics of Cheating in Baseball October 29, 2011 Alan Nathan. 2 News Flash. 3](https://reader035.vdocuments.us/reader035/viewer/2022071216/604861f48cd0b930bc213074/html5/thumbnails/45.jpg)
45
So in conclusion….
• Lots of examples of how physics enters the game of baseballI only covered a tiny fraction here
• I love talking about this stuff so feel free to contact [email protected]
• Or visit my web sitego.illinois.edu/physicsofbaseball
• Thanks for your attention!