The Physics of Hitting a Home Run
Alan M. Nathan
Colloquium, Argonne National Laboratory
September 20, 2002

For a baseball fan, there are few things more satisfying than hearing that sharp distinctive crack of the bat announcing that the ball is on its way to the centerfield seats. For a physicist, there are few things more satisfying than figuring out how something works? And for a physicst who is also a baseball fan, it is pure ecstasy to have figured out much of what is going on during that very brief instant of time when ash meets cowhide. I will try to convey a bit of that excitement as I step you through the physics of hitting a home run. I will focus on two broad topics: the physics of the ball-bat collision and the aerodynamics of the ball in flight. In doing so, I will address various practical issues from a physics point of view, such as the effect of a "juiced" baseball, the "sweet spot" of the bat, the role of the batter during the collision, the differences between wood and aluminum bats, and the role of spin in the flight of the ball. My goal is that all who attend (from physics novices who happen to be baseball fans to senior scientists) find something of interest in this talk, whether it be baseball, physics, or the link between them.