Investigating the coefficient of restitution of major league baseballs

In the middle of the 2015 Major League Baseball season there was a sudden increase in home run rate. Such a sudden league-wide change is difficult to explain, and many baseball pundits suggested that a "juiced" or altered baseball was the culprit. In this thesis, large scale coefficient of restitution (COR) testing is performed on baseballs from before (2014) and after (2016) the alleged change. No evidence is found to suggest that the baseball was altered between 2014 and 2016. The investigation nevertheless revealed telling properties of the coefficient of restitution. First, it was largely found that baseballs from both years fell within the COR specifications of Major League Baseball (between 0.514 and 0.578). Second, the COR is revealed to be a noisy quantity in that the same baseball can exhibit differences in COR on the order of 0.01. Third, most of the variation between baseballs' COR comes from being manufactured on different days in the plant and thus being packaged in different boxes. Additionally, an unexpected fatigue in the strike plate used in the test apparatus is found to have affected the COR measurements for the first 200 trials.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Mechanical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2017

Author dc:creator

• Hesslink, David

Advisor dc:contributor.advisor

• Anette Hosoi.

• Mechanical Engineering.

Statement dc:rights

• MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/112581

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/112581