Lab questions
Asked on the Practice Pitch
Short answers to the questions players, parents and fans send us most. Each one links back to the full experiment.
Rules and Set-Up
How far must the wall be from a free kick?
At least 9.15 m (10 yards), under Law 13 of the IFAB Laws of the Game. Referees often mark the line with vanishing spray.
Can attackers stand in the wall?
Since 2019, attackers must stay at least 1 m from a wall of three or more defenders. Breaking this gives the defending team an indirect free kick.
Does the ball model change free kicks?
Yes. Panel number, seam length and surface texture shift the speed at which airflow changes, altering swerve and wobble. See the knuckleball experiment.
Physics
Why does a curling free kick bend more at the end?
Spin decays more slowly than speed, and as the ball slows through the drag crisis, drag rises sharply, so the sideways Magnus force becomes relatively stronger. Full explanation on the curl page.
What is a knuckleball free kick?
A strike with almost no spin. Uneven airflow separation makes the ball wobble and dip unpredictably, often late in its flight.
Which foot surface gives the most curl?
The inside of the foot near the big toe, striking the outer half of the ball with a wrapping follow-through.
Training
Do boots affect spin?
Slightly. Textured uppers can add grip, but contact point and foot speed matter far more than any boot.
How often should I practise free kicks?
Short, focused blocks of 20 to 30 quality strikes, two or three times a week, beat long tired sessions. Follow the progression on the technique page.
Is power or placement more important?
Placement. Moving the target closer to the post gains more time than extra speed does. See finishing and placement.