Title: The Flight of a Baseball
1The Flight of a Baseball
Alan M. Nathan, University of Illinois a-nathan_at_il
linois.edu http//go.illinois.edu/physicsofbasebal
l
- Introduction
- PITCHf/x and HITf/x
- Using baseball to learn about physics
- Using physics to learn about baseball
- -how pitchers do what they do
- -how batters do what they do
2Forces on a Spinning Baseball in Flight
- Drag slows ball down
- Magnus mg deflects ball from straight line
3Real vs. Physics 101 Trajectory Effect of
Drag and Magnus
4PITCHf/x and HITf/x
- Two video cameras _at_60 fps
- high home and high first
- tracks every pitch in every MLB ballpark
- all data publicly available on web!
- tracks initial trajectory of batted ball
- Used for analysis, TV broadcasts, MLB Gameday,
etc.
5So what good is a physicist in all this?
- Minimal parametrization of the trajectory
- Constant acceleration works very well for pitched
ball - Batted balls ???
- Determining Magnus acceleration
- spin movement important for studying pitching
- Dealing with noisy data, miscalibrations, etc.
- Keeping everyone honest
- Measurements have uncertainties!
6Baseball AnalysisUsing PITCHf/x to discover
how pitchers do what they do
Hitting is timing. Pitching is upsetting
timing.
7Ex 1 Mariano Rivera Why is he so good??
Three Reasons Location, Location, Location
8Ex 2 Late Break Truth or MythMariano
Riveras Cut Fastball
9Ex 2a What makes an effective slider
Josh Kalk, THT, 5/22/08
This slider is very effective since it looks like
a fastball for over half the trajectory, then
seems to drop at the last minute (late break).
side view
10Ex 3 A Pitchers Repertoire LHP Jon Lester,
August 2007
Catchers View
11Ex 4 Jon Lester vs. Brandon Webb
15 inches
Brandon Webb is a sinkerball pitcher Almost no
rise on his fastball
12Ex 5 The Knuckleball
Tim Wakefield is a knuckleball pitcher Chaotic
Movement
13Studies of Batted Balls
- HITf/x ? v0,?,?
- Hittracker (Greg Rybarczyk)
- Landing point
- Flight time
- Together these constrain the full trajectory
14Hitting a Long Fly Ball
R vs. v0
R vs. ?0
USEFUL BENCHMARK 400 ft _at_ 103 mph 5 ft per mph
peaks _at_ 25o-35o
15What Constitutes a Well-Hit Ball?
w/o home runs
home runs
V0gt90
16Putting Spin on Batted Balls
- undercutting/overcutting ? backspin/topspin
- upward/downward Magnus force
- In front or behind ? sidespin
- sideways Magnus force
17Some Familiar Effects Due to Spin
- Balls hit to left/right break toward foul line
18Extract sidespin vs. ? from trajectory
CF
RF
LF
RF
LF
RF
LHH
RHH
?
- Balls break toward foul pole
- Break increases with angle
- Ball hit to CF slices
- LHH/RHH asymmetry
- Tilt in bat
19(No Transcript)
20Some Familiar Effects Due to Spin
- Balls hit to left/right break toward foul line
- Topspin makes line drives nose-dive
- Backspin keeps fly ball in air longer
- Tricky popups to infield
21Paradoxical Popups
Watch for fielders confusion and for bounce of
ball
22HITf/xhittracker Analysis The carry of a
fly ball
- Motivation does the ball carry especially well
in the new Yankee Stadium? - carry (actual distance)/(vacuum distance)
- for same initial conditions
-
23HITf/x hittracker Analysis4354 HR from 2009
Denver
Cleveland
Yankee Stadium
24Summary
- We are on the verge of major breakthrough on
our ability to track baseballs and determine the
aerodynamic effects - The new tools I have discussed are already
revolutionizing baseball analysis - And the tools are getting better.
- So, fun times ahead for me
shown here doing experimental baseball physics