1. APS/DFD, Nov. 20091 The Flight of a Baseball Alan M. Nathan, University of Illinois a-nathan@illinois.edu http://go.illinois.edu/physicsofbaseball 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. APS/DFD, Nov. 20092 Forces on a Spinning Baseball in Flight mg FDFD FMFM Drag slows ball down Magnus + mg deflects ball from straight line

3. APS/DFD, Nov. 20093 Real vs. “Physics 101” Trajectory: Effect of Drag and Magnus

4. APS/DFD, Nov. 20094 PITCHf/x and HITf/x Two video cameras @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. Image, courtesy of Sportvision

5. APS/DFD, Nov. 20095 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! So what good is a physicist in all this?

6. APS/DFD, Nov. 20096 Baseball Analysis: Using PITCHf/x to discover how pitchers do what they do “Hitting is timing. Pitching is upsetting timing.”

7. APS/DFD, Nov. 20097 home plate Ex 1: Mariano Rivera: Why is he so good? ? Three Reasons: Location, Location, Location Home Runs

8. APS/DFD, Nov. 20098 Ex 2: “Late Break”: Truth or Myth Mariano Rivera’s Cut Fastball View from above: actual trajectory -------- linear extrapolation - - - -

9. APS/DFD, Nov. 20099 Josh Kalk, THT, 5/22/08 Ex 2a: What makes an effective slider 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. APS/DFD, Nov. 200910 >90 mph 80-90 mph <80 mph Ex 3: A Pitcher’s Repertoire LHP Jon Lester, August 2007 4-seam fastball 2-seam fastball curveball slider Catcher’s View 4-seam fastball 2-seam fastball curveball slider

11. APS/DFD, Nov. 200911 Ex 4 Jon Lester vs. Brandon Webb Brandon Webb is a “sinkerball” pitcher: Almost no rise on his fastball 15 inches

12. APS/DFD, Nov. 200912 Ex 5 The Knuckleball Tim Wakefield is a knuckleball pitcher: Chaotic Movement

13. APS/DFD, Nov. 200913 Studies of Batted Balls HITf/x  v 0, ,  Hittracker (Greg Rybarczyk) –Landing point –Flight time Together these constrain the full trajectory

14. APS/DFD, Nov. 200914 Hitting a Long Fly Ball R vs. v 0 R vs.  0 USEFUL BENCHMARK 400 ft @ 103 mph ~5 ft per mph peaks @ 25 o -35 o

15. APS/DFD, Nov. 200915 What Constitutes a Well-Hit Ball? w/o home runs home runs HR BABIP V 0 >90

16. APS/DFD, Nov. 200916 Putting Spin on Batted Balls undercutting/overcutting  backspin/topspin –upward/downward Magnus force In front or behind  sidespin –sideways Magnus force friction normal force v friction

17. APS/DFD, Nov. 200917 Some Familiar Effects Due to Spin Balls hit to left/right break toward foul line

18. APS/DFD, Nov. 200918  Extract sidespin vs.  from trajectory CF RF break to right break to leftLF Balls break toward foul pole Break increases with angle Ball hit to CF slices LHH/RHH asymmetry Tilt in bat RF RHH LHH LFRF

19. APS/DFD, Nov. 200919

20. APS/DFD, Nov. 200920 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. APS/DFD, Nov. 200921 Paradoxical Popups Watch for fielder’s confusion and for bounce of ball

22. APS/DFD, Nov. 200922 HITf/x+hittracker 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 (379,20,5.2)

23. APS/DFD, Nov. 200923 HITf/x + hittracker Analysis: 4354 HR from 2009 Denver ClevelandYankee Stadium

24. APS/DFD, Nov. 200924 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