The use of aerodynamic forces by the expert golfer was demonstrated to me once by a drive off the tee by a well-known professional, Arnold Palmer. I stood directly behind him so that I could have the best view of the flight of the ball. Instead of the ball going on the path I had expected, it climbed in a nearly straight line for about 3 s and only then began to fall. Recall that Newton's First Law states that a body continues in a straight line at constant speed unless a force acts on it. The nearly straight line path indicated an almost zero net force acting on the ball in the vertical direction. Where did this lifting force about equal to the weight of the ball come from? It was the aerodynamic force on the dimpled spinning ball, traveling at a high speed, which was balancing the vertical force of gravity. Every person who has ever hit a golf ball with a club realizes that the flight of the ball is affected by these aerodynamic forces. Without the force of the air on the ball, the ball would travel on a very different path than it actually does. If you toss a ball a short distance, it will move accurately on a parabolic path because the force by the air on a slowly moving ball is small. When a well hit ball travels at speeds up to 140 miles per hour, the force of the air on the ball is not small. This force, in some cases, can become even larger than the weight of the ball and can produce spectacular modifications in its flight path. THE EARLY GOLF BALLThe early golf ball was a spherical leather pouch filled, while wet, with wet goose feathers. The pouch was stitched with linen thread, turned inside out so that the stitching was on the inside, and filled with all the feathers that could possibly be forced into it through a small hole which was then carefully closed by a few more stitches. The ball dried to become very hard. It was then oiled and whitened to become an expensive golf ball. The ballmaker could only make four or five i...
