Fisika dan Sepak Bola

In 1996, the Nobel Prize in Chemistry was awarded to three chemists for their discovery of a carbon molecule known as the "buckyball". The buckyball was named after the famed architect R.Buckminster Fuller whose unique structures called Geodesic Domes resembled soccer balls.

Mathematically, the buckball (and the soccer ball) is an Archimedean Solid called a "truncated icosahedron" - a polygon with 60 vertices and 32 faces, 12 of which are pentagons (5-sided objects) and 20 of which are hexagons (6-sided objects).

In 1999, buckyballs were found trapped inside a 4.6-billion-year-old meteorite that landed in Mexico three decades ago.
Recently, groups of buckballs have been used to fight cancer.

Consider a free kick taken by the great Brazilian World Cup player, Roberto Carlos. The ball is kicked the ball with high speed (70 mph) with a high spin (10 rev/sec).

At first, airflow past the rocketing ball has low-drag and high turbulance. However, about 10 m along its trajectory (just as it shoots wide of a wall of poised defenders) the ball slows enough for it to enter into a smooth-airflow (laminar) phase. This create an ever increasing degree of drag, which in turns brings the Bernouilli principle (and a hefty sideways force, or "lift") into play, dramatically curving the ball past the goalie into the net. GOAL!!


NIELS BOHR
(soccer player, physicist)


Niels Bohr was a renowned soccer player as a student but he is best known for the investigations of atomic structure and for work on radiation, which won him the 1922 Nobel Prize for physics.
Einstein expressed grave doubts about Bohr's interpretation of Quantum Theory. Bohr and Einstein spent many hours in deep discussion, but Bohr's view prevailed.
Bohr's other major contributions include his theoretical description of the periodic table of elements, his theory of the atomic nucleus being a compound structure, and his understanding of uranium fission.


HOW A PHYSICIST'S BRAIN WORKS

When a soccer ball is kicked, it is compressed. Assuming the ball is struck through its center, the amount of compression depends mostly on the pressure in the ball, initial velocity of the ball and the speed of the foot striking the ball with the mass of the leg and the mass of the ball being two additional variables but, these last two do not vary much.

What does a physicist ask him/herself?

• How much compression takes place for a reasonable set of parameters?
• How long in time is the ball incontact with the foot?
• How far do the foot and ball travel while they are in contact?
• What makes the ball spin? Is it striking the ball off center, or is it a movement of the foot away from a path through the ball's center during the period of contact, or both?

A ROBOTIC KICK

Members of the Field Robotics Center of Carnegie Mellon University have been involved in the design and building of an experimental soccer- ball kicking robot for a large sports-shoe company in order to perform unbiased and repeatable experiments to improve upon shoe and soccer-ball designs.
The leg was designed to approximate as close as possible the human kinematics and dynamics during the action of kicking a soccer ball. The purpose was to provide a consistent test-bed to remove the statistical variance associated with human testing and thus provide objective comparison criteria to judge and drive the design of new soccer-shoe prototypes.

HE DID THE MATH FOR YOU!


Leonhard Euler was one of top mathematicians of the eighteenth century and the greatest mathematician to come out of Switzerland. He made numerous contributions to almost every mathematics field and was the most prolific mathematics writer of all time. It was said that "Euler calculated without apparent effort, as men breathe...." He was dubbed "Analysis Incarnate" by his peers for his incredible ability.
Euler's polyhedral formula states that, for any simply connected polyhedron, the number of faces (F) minus the number of edges (E) plus the number of vertices (V) is always equal to 2, or stated mathematically: F - E + V2
For a soccer ball, which has the shape of a truncated icosahedron with 32 faces, 90 edges, and 60 vertices: 32 - 90 + 602

HOW HIGH WAS THAT GOAL KICK?

Suppose a goal kick is booted 36 feet into the air. When it finally comes down, it bounces up off the grass 12 feet. The formula for the coefficient of restitution (c) is , where h=the bounce height and H=the drop height.
The coefficient of restitution is a measure of the elasticity of the collision between the ball and the ground. Elasticity is a measure of how much bounce there is, or in other words, how much of the kinetic energy of the colliding objects before the collision remains as kinetic energy of the objects after the collision.
A perfectly elastic collision has a coefficient of restitution of 1. Example: two diamonds bouncing off each other. A perfectly plastic, or inelastic, collision has c=0. Example: two lumps of clay that don't bounce at all, but stick together. So the coefficient of restitution will always be between zero and one.
In the above example, c=0.58. If the ball had bounced up only 6 feet, the coefficient of restitution would have been 0.41
How do you think the height of the grass, moisture, and temperature might affect the coefficient of restitution?

sumber:

http://physics-of-sport.net/