Math in soccer
Date: 05/21/99 at 11:45:38 From: Elise Ricard Subject: Math in soccer I need to write a paper about how math is involved in soccer. So far, I have said some things like the field measurements and that they relate to area and perimeter. That is all I have so far.
Date: 05/24/99 at 13:41:09 From: Doctor Floor Subject: Re: Math in soccer Hi, Elise, Thanks for your question! You can read more about the soccer ball in the Dr. Math archives: http://mathforum.org/dr.math/problems/monaghan10.29.98.html The task of a goalkeeper also involves geometry: Think of the following problem: if an attacking player is approaching the goalkeeper, where does the goalkeeper need to stand to have the best chance of preventing a score? A good goalkeeper does not stand on the goal line too much of the time. He stays a bit in front of his goal, because it makes no sense to dive behind the goal line to "save" a ball. When a single attacker is approaching him, he will try to be on the angle bisector of the lines from that player to the goal posts. He will turn his body toward the approaching player, so that when he dives to the side to stop a shot, he is as far from the lefthand side as from the righthand side. P---------goal---------P / / / ****GK / / * / / / / / / / / / Attacker The shortest distances from the goalkeeper (GK, on the not-drawn angle bisector) to the lines from the attacker to the goal posts are perpendicular to these lines ("drawn" as ***). So the goalkeeper will not dive to the side, but to maximize his reach he will always dive slightly forward. This is a simplification, because in the sketch above the attacker finds more space to curve the ball on the righthand side of the Goalkeeper (seen from the Attacker's viewpoint) than he finds on the lefthand side. Top players can use this to score very funny goals. I remember one by a Dutch player of Ajax Amsterdam (Peter van Vossen) a few years ago like this: P--------goal--------P GK **** Van Vossen ***** ******** ******* ************* ********** *********** There also are interesting dilemmas for the goalkeeper about how far he should stand in front of his goal: when he is far from his goal the goalkeeper can get a single player's ball more easily, but the attacking player can also more easily lob the ball over the goalkeeper. And when a second player is coming at the same time, that player has a free path to the goal. I hope you can use these ideas. Good luck on your paper! Best regards, - Doctor Floor, The Math Forum http://mathforum.org/dr.math/
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