http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
effect of angle, velocity, and rotation of incidence on the angle deviation of rebounding tennis balls
The purpose of this study was to describe the relationship between the three predictor variables of angle of incidence (AI), velocity of incidence (VI), and rotation of incidence (RI) and the criterion variable of angle deviation (AD) of rebounding tennis balls. A total of 30 observations were recorded by the Lccam high-speed camera operating at 400 frames per second and positioned at a right angle to the line of flight of the ball at the point of rebound. The tennis balls were projected from a Prince ball machine suspended above a Laykold court surface. The angles of projection were approximately 15, 30, 45, 60, and 75 degrees. The balls were projected at two different velocities, and with either topspin, backspin, or no spin. A significant relationship was found to exist between the criterion variable and the three predictors. The proposed model was shown to account for 79.58% of the variation in AD. The variable VI was found to have no statistical significance in the prediction of AD, and was subsequently omitted from the model. The resulting two variable model could account for 79.54% of the variation in AD. The single most influential variable in the prediction of AD was RI, which accounted for 42% of the variation in the criterion variable. Angle deviation was greatest for balls that were projected with backspin and least for balls that were projected with topspin. The variable AI was significant in the prediction model, even though it could account for only 9.8% of the variation in AD by itself. Tennis balls which impacted the surface at an angle less than 45 degrees experienced a greater AD than those which impacted at an angle greater than 45 degrees. Angle of incidence and rotation of incidence each have a significant effect upon the angle deviation of a rebounding tennis ball. When these two variables are known, it is possible to predict angle deviation.
Includes bibliographical references (leaves 113-121).