AERODYNAMICS of SOCCER

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The shape of a soccer ball resembles that of an allotrope of carbon called a “buckyball”, which was named after an architect, Buckminster Fuller.  It is a polygon with 60 vertices and 32 faces that come together to make its aerodynamic qualities.   The aerodynamic qualities of a soccer ball are routinely described by the interaction of the soccer ball with the atmosphere.

SPINNING a BALL WHILE in the AIR

Sometimes in the game, it is important and necessary to make the ball curve around opponents.  In this view of a spinning soccer ball, the closer the air is to the center of the ball, the faster it travels.  According to Bernoulli’s principle, the pressure on a ball can be reduced if the ball is rotating the same was as the airflow.  Bernoulli’s principle says that “when speed is high, pressure is low”, and vice versa.  When the pressure is low on one side of the ball, the other side has high  pressure and this pressure difference between the two sides of the balls cause the ball to swerve to one side.

To curve the ball, it must be initially kicked off-center to create a side spin.  If the ball is kicked with high speed, it will enter a smooth-airflow help to bring in a large sideways force.

BERNOULLI’S PRINCIPAL in ACTION

Roberto Carlos, a famous soccer player, is known for his amazing shot that curved around all of the defenders and instantly turned into the corner of the goal.  To get his desired position, Roberto Carlos kicked the ball with enough force and includes enough of a roll to produce a rotation spin on the kick.   The speed at which he could kick the ball had a great influence on the amount of curvature of the ball.   Carlos kicked it with the outside of his foot, allowing him to hit the ball hard at approximately 70 mph.  The ball then fell into a laminar flow regime and the ball curved into the goal

new DEVELOPMENTS

A new soccer ball has come out with improved dynamics.  The traditional ball encountered problems because of its round shape and smooth surface.  These qualities cause air to stick to the front of the ball and cause it to slow down.  A new type of ball marketed by Puma has small dimples on the surface inspired by the gold ball that are made to redirect air to the back of the ball increasing the speed about 20%.   As the website says, “This results in less drag and straighter, smoother flights.” This new type of ball is pictured to the right with its golf-like dimples.  It is priced online for \$100.

BOUNCING of a BALL:  a okSAMPLE PROBLEM

Suppose a soccer ball is dropped from rest at a height of 10 feet. And assume, on each successive bounce, the ball reaches half the previous height attained. How long will it take for the ball to finally come to rest?
Surprisingly, most people immediately and incorrectly guess that the time involved would be infinite. But, the time of each bounce shortens quickly, and using the simple expression d=½ × g × t² for the distance (d) traveled from rest during the time (t) under gravity (g=32 feet/sec/sec), an infinite series leads to a finite time of 4.61 seconds for the ball to come to rest.  (problem taken directly from Einstein website, final link on this page).