At a recent training session, Sascha Goerres of the Richmond Kickers worked with Nick on bending the ball in flight. Not only did Nick get a good skills lesson on free kicks, but Sascha explained the physics behind the phenomenon.
It is the Magnus effect, he said, that occurs when a player creates spin on the ball. Performed well, a kick that uses the Magnus effect causes the ball to curve around a wall of defenders, fool the eye and reflex of the keeper, and hit the corner of the goal.
Since I’m a homeschool mom, I had to look into this so Nick and I could discuss it further, and I found that Physics World has a good explanation:
Consider a ball that is spinning about an axis perpendicular to the flow of air across it. The air travels faster relative to the centre of the ball where the periphery of the ball is moving in the same direction as the airflow. This reduces the pressure, according to Bernouilli’s principle. The opposite effect happens on the other side of the ball, where the air travels slower relative to the centre of the ball. There is therefore an imbalance in the forces and the ball deflects. . . . This lateral deflection of a ball in flight is generally known as the “Magnus effect”.
The forces on a spinning ball that is flying through the air are generally divided into two types: a lift force and a drag force. The lift force is the upwards or sidewards force that is responsible for the Magnus effect. The drag force acts in the opposite direction to the path of the ball. (Read more from Physics World).
Of course, soccer players can practice bending the ball without knowing the name of the physics principle, and they will intuitively come to know that the spin they create changes the trajectory of the ball. Striking the ball off center with a lot of force produces the spin, and practicing a lot so the athlete can refine control of the variables makes it effective.
Still, understanding why is a nice way to combine academics and sport.
Sascha and I were also talking about the recent article in Men’s Health about the smartness of pro soccer players. An excerpt:
When professional soccer players were tested on “executive function”—a key aspect in memory, multitasking, and creativity—they scored significantly higher than the general population. In fact, elite players belonged to the best 2 to 5 percent of the total population, says Predrag Petrovic, Ph.D., the lead researcher and professor at Karolinska Institute in Stockholm.
Why? Soccer players have to adapt constantly to a rapidly changing environment to perform well, says Petrovic. That’s easily translated to tests of executive functions like changing strategies and suppressing old, outdated plans, he adds.
“People assume that if you have a gifted arm or can kick a ball that you aren’t smart, you don’t need to be smart, or both,” says Kristen Dieffenbach, Ph.D., professor at West Virgina University. “High-level sport is physically demanding and requires high-level cognitive skills.”
I don’t know if this exactly translates to youth soccer, but I can only assume that practicing in increasingly demanding situations at higher speeds requires quicker decision-making and the body’s execution of those decisions in a fraction of a second. That must be a good thing.
And if that’s not as measurable in youth soccer, I’ll take the benefits of fresh air, fitness, discipline, camaraderie, humility, competitiveness, work ethic, physical exertion, and joy in the game.
And a physics lesson here or there.