Physics 199BB The Physics of Baseball

Physics 199BB The Physics of Baseball Fall 2007 Freshman Discovery Course Alan M. Nathan 403 Loomis 333-0965 a-nathan@uiuc.edu Textbook for Course Bob Adair ―Blending scientific fact and sports trivia, Robert Adair examines what a baseball or a baseball player in motion does—and why. How fast does a batted ball go? What effect do stitch pattens have on wind resistance? How far does a curveball break? …The answers are often surprising—and always illuminating.‖ We will cover the entire book. Other Useful Books ―The book is written for the inquiring layperson…‖ ―…many controversial claims about the game are addressed and…resolved by this book.‖ Other Useful Books ―The primary purpose of this book is to collect and present in one place interesting examples of the physics of sport for the benefit of physicists, physics teachers, students, and other sports-minded and scientifically curious readers.‖ Some good articles, but lots has happened since 1992. Other Useful Books Internet Resources • My web site: – http://webusers.npl.uiuc.edu/~a-nathan/pob – I try to keep the site up to date with the most current links • PITCHf/x Gameday Logs – http://gd2.mlb.com/components/game/mlb/year_2007/ – Useful for analysis of pitched ball trajectories • Hittracker – http://www.hittrackeronline.com/ – Useful for analysis of home run trajectories Organization of the Course • Monday, 3-5 PM – Rm. 236 Loomis – Sometimes Rm. 257 Loomis (computer lab) • Sometimes we will do ―labs‖ – – – – – High-speed camera Pitching machine ―modal analysis‖ equipment Computer calculations … • Hopefully we can watch the Illini practice What do I expect of you? • Come to class – Participate in discussion • Do homework – Mostly computer exercises • Do a special project – Research project, paper, presentation, … – More on this later Additional Resources • Physics of Baseball Blog: https://teamphysics.physics.uiuc.edu/SiteDirect ory/PHYS199BBBlog/default.aspx • Physics of Baseball Wiki: https://teamphysics.physics.uiuc.edu/SiteDirect ory/PHYS199BBwiki/default.aspx • Physics of Baseball Teamsite: https://teamphysics.physics.uiuc.edu/SiteDirect ory/PHYS199BBTeam/default.aspx After taking this course, you will be able to answer the following questions: • • • • • • • What matters more: pitch speed or bat speed? Does ―juicing‖ the ball make a difference? What/where is the ―sweet spot‖? What is the ideal bat weight? Is corking the bat effective? Does the batter’s grip matter? Why does aluminum outperform wood? By how much? • Can a curveball be hit farther than a fastball? After taking this course, you will be able to answer the following questions: • • • • • • Is there such a thing as a rising fastball? How much does a curveball break? How does a knuckleball work? What the heck is a gyroball? Why do fly balls often curve toward the foul line? Why are popups to the infield often difficult to catch? • How far did that home run travel? and lots more…. A Philosophical Note: “…the physics of baseball is not the clean, well-defined physics of fundamental matters but the ill-defined physics of the complex world in which we live, where elements are not ideally simple and the physicist must make best judgments on matters that are not simply calculable…Hence conclusions about the physics of baseball must depend on approximations and estimates….But estimates are part of the physicist’s repertoire…a competent physicist should be able to estimate anything ...” “The physicist’s model of the game must fit the game.” “Our aim is not to reform baseball but to understand it.” ---Bob Adair in “The Physics of Baseball”, May, 1995 issue of Physics Today More Philosophy • Physics is an experimental science • What tools are there at our disposal? – The game itself—the ultimate laboratory – Tools to study bats and batting • Low speed collisions -- movie clip • High speed collisions – movie clip • Modal analysis of bat vibrations – demo and next slide – Tools to study the flight of the baseball • • • • High-speed video – movie clip PITCHf/x – movie clip plus slide Trackman radar Motion analysis Modal Analysis of a Baseball Bat www.kettering.edu/~drussell/bats.html f1 = 179 Hz f3 = 1181 Hz f2 = 582 Hz FFT(R) 1 0.5 0 5 10 15 20 25 30 35 f4 = 1830 Hz 0.15 582 0.1 frequency 1181 1830 R 0 -0.5 0.05 -1 -1.5 179 time 0 5 10 t (ms) 15 20 2400 0 0 500 1000 1500 frequency (Hz) 2000 2500 Vibrations and Broken Bats pitcher movie 0.000 5.000 10.000 15.000 20.000 25.000 30.000 35.000 catcher Barry Bonds’ 756th Home Run 200 150 Bonds #756 100 50 0 0 100 200 300 400 horizontal distance (ft) 500 Thanks to J. J. Crisco & R. M. Greenwald Medicine & Science in Sports & Exercise 34(10): 1675-1684; Oct 2002 19 Basic physics and math that we will review quickly: • Velocity and acceleration – Motion with constant acceleration: • x(t) = x0 + v0t + 1/2at2 • Forces and Newton’s Three Laws – Especially the 2nd law • F = ma • Vectors • Geometry and trigonometry See handout sheet First Assignment • Read Chapters 1 and 2 of Adair • Make sure you have Excel installed on your computer and know how to use it