The Flight of a Baseball - PowerPoint PPT Presentation

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The Flight of a Baseball

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Using baseball to learn about physics Using physics to learn about baseball-how pitchers do what they do ... Thus far, only perfect hits Basketball demo. – PowerPoint PPT presentation

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Title: The Flight of a Baseball


1
The 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

2
Forces on a Spinning Baseball in Flight
  • Drag slows ball down
  • Magnus mg deflects ball from straight line

3
Real vs. Physics 101 Trajectory Effect of
Drag and Magnus
4
PITCHf/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.

5
So 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!

6
Baseball AnalysisUsing PITCHf/x to discover
how pitchers do what they do
Hitting is timing. Pitching is upsetting
timing.
7
Ex 1 Mariano Rivera Why is he so good??
Three Reasons Location, Location, Location
8
Ex 2 Late Break Truth or MythMariano
Riveras Cut Fastball
9
Ex 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
10
Ex 3 A Pitchers Repertoire LHP Jon Lester,
August 2007
Catchers View
11
Ex 4 Jon Lester vs. Brandon Webb
15 inches
Brandon Webb is a sinkerball pitcher Almost no
rise on his fastball
12
Ex 5 The Knuckleball
Tim Wakefield is a knuckleball pitcher Chaotic
Movement
13
Studies of Batted Balls
  • HITf/x ? v0,?,?
  • Hittracker (Greg Rybarczyk)
  • Landing point
  • Flight time
  • Together these constrain the full trajectory

14
Hitting 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
15
What Constitutes a Well-Hit Ball?
w/o home runs
home runs
V0gt90
16
Putting Spin on Batted Balls
  • undercutting/overcutting ? backspin/topspin
  • upward/downward Magnus force
  • In front or behind ? sidespin
  • sideways Magnus force

17
Some Familiar Effects Due to Spin
  • Balls hit to left/right break toward foul line

18
Extract 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)
20
Some 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

21
Paradoxical Popups
Watch for fielders confusion and for bounce of
ball
22
HITf/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

23
HITf/x hittracker Analysis4354 HR from 2009
Denver
Cleveland
Yankee Stadium
24
Summary
  • 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
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