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The purpose of this study was to determine the minimum and maximum velocity of the tennis ball for selected heights of contact and angles of projection and wall impact points during the tennis serve. By use of a ballistics formula, a number of variables which determine the trajectory of the tennis ball were programed for the computer. Tables were tabulated and are available for all data gathered. Angles of projection from the horizontal were selected to range from −5° to 15° in increments of 1°. Velocity of the serve ranged from a low of 30 ft. per second to a high of 176 ft. per second. Finally, the height of the contact point ranged from a low of 6.0 ft. to a high of 9.0 ft. in increments of .5 ft. Height of the ball when crossing the net (impact point on the practice court) ranged from a low of 3.01 ft. to a high of 8.47 ft. The minimum height at crossing was achieved at 6.5 ft. service height, a −3° angle of projection and time from baseline of .30 sec. This is a relatively high velocity serv...

The purpose of this study was to determine the range and angle of leg thrust in the performance of a successful gymnastic mat kip. It was assumed that a maximum angle of leg thrust had a direct relationship to success or failure and that, all other factors being equal, the angle of leg thrust should be the determining factor for successful performance. Twenty-eight subjects from two separate male college classes participated in the experiment. The findings of the data indicated that for a successful kip the mean angle of leg thrust was 52°. For an unsuccessful kip the mean angle was 64°.