Characterization of the effect of temperature on baseball COR performance

In the game of baseball, the bat-ball collision is of great interest to both the fan and the scientist. The performance of baseball bats has been investigated and while there are plenty of ways of changing their performance, bats do not perform significantly different under different climate conditions. Baseballs, being made of a combination of cowhide, yarn and rubber, can change weight when exposed to a different humidity, which in turn can result in a change in performance of its collision with a bat. Additionally, during the course of a year, baseballs are exposed to a variety of outdoor temperatures. This paper will discuss the effect of temperature on the performance of a standard collegiate baseball. Using standardand high-speed COR testing methods, the effect of both heating and cooling of a baseball will be investigated. The results from the standard COR test show that there is only a slight increase in performance with the heating of a baseball to an elevated temperature beyond the extreme of what would be experienced in normal play. There is a much more significant change in performance when a baseball is cooled. The performance decrease can be as much as 4% when the ball is subjected to subfreezing temperatures. The results of this study will help the scientific spectator understand how the game might change under different temperature conditions.