An expert examined the official ball used at the soccer World Cup Qatar tournament, which will start in November, and found that when compared assuming that a professional player kicks a free kick at a distance of 25 meters, the previous tournament. It turned out that it has characteristics that it is easy to curve, such as the width of the curve is larger than that of the official ball of .

The official ball of the soccer World Cup Qatar tournament "Al Refra" is designed to reduce air resistance by using 20 panels with different shapes of two types, large and small, and furthermore, by adding fine undulations to the surface. It means that the stability when the ball flies is improved.



Professor Kazuya Seo of Kogakuin University, who has been investigating the characteristics of the official World Cup ball since the 2002 Japan-Korea tournament, conducted an experiment to reproduce the situation in which a ball kicked against a strong wind flies.・I compared the ball "Telstar" of the last Russian tournament with the ball "Refura".



As a result, it was found that "Al-Rifla" has a greater force to float the ball when backspin is applied compared to "Telstar", and it is easy to curve when side-spin is applied.



For the side spin, we simulated the trajectory of the ball, assuming that a professional player kicks a free kick from a distance of 25 meters to the goal at a speed of 28 meters per second and making 6 rotations per second.



And although the time to reach the goal was exactly the same at 1.071 seconds, it was found that "Al Rifra" bends 42 centimeters, which is about two balls the size of the ball.



Also, in the simulation of goal kicks, the flight distance was almost the same, but "Al Rifra" had a longer flight time by about 0.2 seconds.

Professor Seo said, "This ball floats well and bends well. By changing the design of the surface, this kind of difference can be seen. Curving two balls at the same speed is an opportunity for a striker to show off his skills and score goals." The keeper needs to know in advance and react quickly," he said.