Center of percussion of hand-held implements

American Journal of Physics

Volumn 72, Issue 5, 2004, Pages 622-630

  Cross, Rod ^a  

^a UNIVERSITY OF SYDNEY   (Australia)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 2442560631     PISSN: 00029505     EISSN: None     Source Type: Journal    
DOI: 10.1119/1.1634965     Document Type: Article

References (16)

1. H. Brody, "Physics of the tennis racket," Am. J. Phys. 47, 482-487 (1979).
2. H. Brody, "Physics of the tennis racquet. II The sweet spot," Am. J. Phys. 49, 816-819 (1981).
3. G. W. Ficken, "Center of percussion demonstration," Am. J. Phys. 44, 789 (1976).
4. R. Cross, "The sweet spots of a tennis racquet," Sports Eng. 1, 63-78 (1998).
5. U.S. patents 3,999,756 (H. Head), 4,165,071 (J. L. Frolow) and RE33372 (J. L. Frolow).
6. R. Cross, "The sweet spot of a baseball bat," Am. J. Phys. 66, 772-779 (1998).
7. H. Hatze, "Center of percussion of tennis rackets: A concept of limited applicability," Sports Eng. 1, 17-25 (1998).
8. 〈www.picotech.com〉 has details of the unit used and the accompanying software that allows one to convert a PC into an excellent digital storage oscilloscope or spectrum analyzer
9. Piezo disks generate an output voltage directly proportional to the force on the disk. If the disk is stationary, an equal and opposite force on each side of the disk generates the voltage. If the disk is attached on one side to a moving object, then the force acting on the side of the disk attached to the object is given by the mass of the disk times its acceleration. In the latter case, the output voltage is proportional to the acceleration of the object to which it is attached. Commercial accelerometers often have an additional small mass attached to the piezo element to increase its sensitivity, but this was not needed in the present experiment. A piezo element behaves electrically as a capacitor with an induced charge proportional to the force on the piezo. If the force remains constant, then the charge remains constant unless one attempts to measure it. The charge decays with a time constant RC, where R is the resistance of the measuring device and C is the capacitance of the piezo plus any capacitor connected in parallel with the disk.
10. H. Brody, R. Cross, and C. Lindsey, The Physics and Technology of Tennis (RacquetTech, Solana Beach, CA, 2002), pp. 93-94, 138-146.
11. R. Cross, "Impact of a ball with a bat or racket," Am. J. Phys. 67, 692-702 (1999).
12. A. Nathan, "Dynamics of the baseball-bat collision," Am. J. Phys. 68, 979-990 (2000).
13. R. Cross, "Flexible beam analysis of the effects of suing tension and frame stiffness on racket performance," Sports Eng. 3, 111-122 (2000).
14. G. S. Sawicki, M. Hubbard, and W. J. Stronge, "How to hit home runs: Optimum baseball bat swing parameters for maximum range trajectories," Am. J. Phys. 71, 1152-1162 (2003).
15. R. Adair, "Comment on the sweet spot of a baseball bat," Am. J. Phys. 69, 229-232 (2001).
16. H. Hatze, "Impact probability distribution, sweet spot, and the concept of effective power region in tennis rackets," J. Appl. Biochem. 10, 43-50 (1994).