Today’s baseball game, brought to you by Physics Unlimited, is a blockbuster contest between the famous Mathematical Physicists and Washington State University’s own Oblique Collisions.
As the Oblique Collisions take the field, Ernest Rutherford, the renowned English physicist, is first up for the Mathematical Physicists. Better known outside physics circles for his cricketing skills, Rutherford is quite the hitter, though usually of particles much smaller than baseballs.
Indeed, in describing the collision of an alpha particle—better known as the nucleus of a helium atom, two protons and two massive neutrons—with a gold atom, Rutherford had this to say: “It was as if you fired a 15” [artillery] shell at a piece of tissue paper and it came back to hit you.”
Swing and a miss! Strike one against the discoverer of some of the basic properties of particle physics.
Jeffrey Kensrud, manager of the WSU Sports Science Lab in Pullman, is on the mound winding up another pitch. Crouched behind home plate—and wearing safety gear of course—is Lloyd Smith, director of the lab.
Kensrud fires, and it’s another 88 MPH fastball. Rutherford swings, connects, and oh my! We’re seeing a spin rate of 3,500 RPM as the Oblique Collision outfielders drop back, back…home run! No wonder Rutherford was called a force of nature!
Isaac Newton is next up, adjusting his powdered wig, and taking a few practice swings. The all-star mathematician, not known for his baseball skills, is in fact a master of the game. Newton is heard to say, “Check this coefficient of restitution, baby,” and then smacks one over the center field fence.
Another home run for the Mathematical Physicists.
Later, in a post-game interview, Smith and Kensrud talk about what went wrong.
“It’s not that we played poorly,” says Smith. “Rather, these guys are the masters of scatter experiments. I mean, Rutherford defined that move in the early twentieth century. We used the same principles in our efforts to understand what happens to a baseball when hit with a bat—as we recently wrote in a paper on the subject, ‘some of the same principles that apply to subatomic collisions also apply to collisions of macroscopic objects.’”
Kensrud nods, and adds, “And Sir Isaac developed the math that tells us how fast a hit object goes, based on the coefficient of restitution. Simply divide the velocity after collision by the velocity before collision.”
“That sounds simple,” says the interviewer. “So, all the energy of the swinging bat is converted into ball velocity?”
“Not all,” explains Kensrud. “The ball is slightly deformed, absorbing some of that energy, while some of the rest is lost to friction of bat against ball.”
“But what you really want,” interjects Smith, “is to minimize the loss of kinetic energy and to maximize the post-impact spin by maximizing both the normal and tangential coefficients of restitutions.”
There is joy in Mudville at this insight.
Final score: Mathematical Physicists, 3, Oblique Collisions, 0, but the Collisions score many bonus points for their high-speed photography of bat-whacked spinning balls.