@article{oai:nagoya.repo.nii.ac.jp:02005198,
 author = {SAKURAI, Shinji and IKEGAMI, Yasuo and YAMAMOTO, Yuji and NUNOME, Hiroyuki and TERASHIMA, Toru and YABE, Kyonosuke},
 issue = {1},
 journal = {総合保健体育科学, Nagoya Journal of Health, Physical Fitness & Sports},
 month = {Mar},
 note = {The purpose of this study was to investigate the three-dimensional trajectory of fastball (FB), curveball (CB), slider (SL) and forkball (FK) baseball pitches thrown by a professional player. Flight was recorded with two synchronized video cameras (60 Hz) and analyzed using DLT procedures. A second order polynomial function using the least square method was used to derive timc-displacement data of ball trajectory for each pitch. Estimated vertical acceleration during the flight was -4.5 (FB), - 12.9 (CB), -7.4 (SL), and -9.6 m/s^2 (FK), respectively. The mean ratio of final/initial velocity of the horizontal velocity of the pitch was 0.877 (FB), 0.864 (CB), 0.882 (SL), and 0.850 (FK). These results suggest that horizontal deceleration rather than vertical drop in the latter part of the flight is the unique characteristic of the forkball.},
 pages = {13--18},
 title = {Trajectory of a pitched baseball : How and why does the forkball break downward?},
 volume = {25},
 year = {2002}
}