An analysis of the rebound characteristics of wooden baseball bats and aluminum baseball bats

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Authors
Bailey, Chad D.
Advisor
Issue Date
1991
Keyword
Degree
Thesis (M.A.)
Department
School of Physical Education
Other Identifiers
Abstract

The purpose of this study was to determine the rebound characteristics of wooden baseball bats and aluminum baseball bats. Prior to testing, the point of percussion was determined. The bat being tested was suspended by a string that was attached to a small eye screw placed into the end of the knob of the bat. The string attached to the end of the bat was then secured to a point above an open doorway. The bat was placed into a side-by-side swinging motion from a fixed position. Ten completed swings (from the fixed position back to the fixed position) were timed with a stop watch. This swinging and timing process was repeated inch wooden, .98 kilograms; 33 inch aluminum, .90 kilograms; 34 inch wooden, .95 kilograms; and 34 inch aluminum, .89 kilograms) was tested by dropping baseballs from a distance of approximately 170 centimeters above the bat onto the point of percussion. The baseballs were placed in a clamping devise that was located over a circular hole in a piece of wood. The handle of the clamping devise was pulled and the baseball was released. Three baseballs were dropped on each bat, and the rebound distance was measured by a Locam camera. The velocity of the ball before and after contact was measured. An accelerometer was also used to determine the vibration effects of a baseball hitting a bat from a low elevation (an accelerometer is very delicate). The accelerometer was placed under the barrel of the bat. Three baseballs were dropped (using the same clamping devise) on each bat from a distance of approximately nine centimeters above the bat. The vibration effects were measured electronically. An analysis of variance was computed between the velocities of the baseballs as they approached and then rebounded off the baseball bats. The data revealed there were no significant differences between the drop velocities. However, there were significant differences between the up velocities (velocity of the ball after it rebounded off of the bat). There were significant differences between the velocities of the: aluminum 34 vs wooden 34, aluminum 34 vs aluminum 33, and aluminum 34 vs wooden 33.

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