U10/U11 2010R

Did you know that you can curve a ball more on a dry day than on a wet day?

Soccer players can make a ball curve through the air by striking it off its center. If you hit it dead on center, the ball will fly straight. if you hit it to the right, it will curve left, because a spinning ball has lower air pressure on the front side where the spin is going to, and higher pressure where the spin comes from.

Researchers at Yamagata University in Japan studied how people kick soccer balls. Using ultra-fast cameras that can take 4,500 frames per second, they took pictures of players striking a ball. This is their model of the distortions on the ball and on the foot at the point of impact:

 The colors in the model shows the deformations:  pink is the lowest, through blue, green and yellow to red, the highest. "These studies have confirmed what most footballers know. If you kick the ball slightly off-centre with the front of your foot - and with your ankle bent into the shape of an "L" - the ball will curve in flight. This causes the applied force to act as a torque, which gives the ball a spin"

The actual amount of curve depends on two factors:

• the friction between the foot and the ball (or how much the foot can drag the ball). This means that on rainy days there is less curve, because there is less friction!
• the position of the impact: how much off the center of the ball you hit the ball. There is actually an optimum spot to hit the ball off its center. if you go too much off-center, the ball will not spin as much either, because the duration (time) during which contact occurs is too small.

Bending the ball is an important skill to master. It allows attackers to pass balls by defending walls, to deceive the goal keeper, and to score from corner kicks:

Read Users' Comments (0)