1. During a free kick, five or six defensive players line up in a "human wall" in an attempt to block the path to the goal, while the offensive player takes the kick calmly. Slowly walked forward, put the ball in the right position, and then took a fierce shot. The ball circled the "human wall" and was about to deviate from the goal and fly out of bounds. However, it turned around and went straight to the goal. The goalkeeper Just as he was about to start pouncing on the ball, it was too late, the ball had already hit the net.
This is the rather magical banana ball. Because the ball moves in an arc shape, like a banana, it is named "Banana Ball".
The Mystery of the Banana Ball
We know that when the ball is flying in the air, if it not only makes it move forward, but also makes it continue to rotate, because the air has a certain degree of stickiness, so When the ball rotates, the air rubs against the surface of the ball, and the rotating ball drives the surrounding air layer to rotate together. If the ball moves left and right in the horizontal direction and rotates clockwise around the axis vertical to the paper surface, the air flow will not only flow to the right relative to the ball, but also the surrounding air circulation layer driven by the rotation of the ball will follow. clockwise rotation. In this way, the air speed above the ball has rotation in addition to translation to the right, and the two directions are the same; while below the ball, the translation speed (to the right) and the rotation speed (to the left) are in opposite directions, so their combined speed is less than the resultant velocity of the air above the ball.
According to Bernoulli's theorem of fluid mechanics, the pressure on the side with a larger speed is smaller than the pressure on the side with a smaller speed, so the pressure above the ball is smaller than the pressure below the ball. The resultant force of the air pressure on the ball varies up and down, and the total resultant force is upward. If the ball rotates very fast, so that the upward resultant force of the air on the ball is greater than the weight of the ball, then the ball will experience a vertical upward resultant force as it moves forward. , so that when the ball moves horizontally to the left, it will curve forward and upward, and the ball will turn upward. If you want to make the ball turn left and right, just rotate the ball around the vertical axis. It seems that the key is the athlete's footwork at the moment when he touches the ball, that is, not only must the ball move forward, but also the ball must rotate rapidly. Different rotation directions will cause the ball to turn in different directions. This requires hard training for the athletes to practice. Just a set of skilled footwork can only reach the point of perfection after repeated practice. In fact, not only football has "banana balls", table tennis, volleyball, tennis, etc. all use rotation technology to create various erratic and mysterious balls, such as loop balls in table tennis and floating balls in volleyball. Balls, etc. are all created based on this principle. The principle of banana ball is based on aerodynamics. That is, the greater the relative speed between the spherical surface and the air, the greater the force on the spherical surface, and the greater the arc of the ball. Assume that you are looking down from directly above the ball (your line of sight is perpendicular to the ground), and at the same time, the instantaneous direction of the ball's trajectory is vertically upward from your line of sight, and the ball is rotating counterclockwise. The relative friction speed between the right side of the ball and the air is greater than the left side, and the ball's direction of motion will shift to the left. The greater the relative friction speed, the greater the deflection of the ball, that is, the greater the arc. This is the arc, and the following is the height. Suppose you look at the ball from the side (the line of sight is parallel to the ground), and the instantaneous direction of the ball's trajectory is vertical to your left. If the ball rotates clockwise, the relative friction speed between the lower part of the ball and the air is greater than that of the upper part, and the ball will fall slower. This makes it easier to get around the wall (but the ball is slow and gives the goalkeeper too much time to react). On the contrary, the ball will fall faster, but it will not be easy to go around the wall (but going around is a threat).
The active free-kick master in world football
Beckham may have the most expensive right foot in Europe. He is good at taking kicks with the instep, and the ball rotates in a pleasing inward arc. The line flew towards the blind spot of the opponent's gate. Beckham has received professional training since he was a child, and his every move looks very simple and orthodox. In order to increase the speed, he must twist his whole body and tilt his body completely to increase the internal rotation speed of the ball. Therefore, it usually gives people the feeling of lightning speed, which is why we have our common Bayern free kick taking posture. .
The goalkeeper always wonders why he is often half a beat too slow even when he is judging the right direction. However, scientific data tells us that every time Beckham takes a free kick, the ball speed is over 110 kilometers. Now people regard his rotation, speed, and accurate landing point. The curved ball is called "Belgian Curve", which is a simple but deadly and effective weapon in offense. Former free-kick master Platini once commented: "Beckham is definitely the best right-footed free-team player in Europe. If unfortunately you meet the team he plays for, you must not give him anything near the penalty area. Opportunity."
Classic replay: The most exciting kick in the last minute of the 2002 World Cup qualifying match against Greece, worth 100 million!
Ronaldinho is the number one star in the world today. Ronaldinho's free kick speed and arc are perfectly combined. In Gremio, Paris and Barcelona, ??people are used to him using it once. The second accurate half-high ball humiliated the opponent's goalkeeper. In the first year of joining the Red and Blues, he scored 15 goals to help Barcelona return to the top, and then won the title of World Footballer. His status in the national team has also skyrocketed. Now, unless he is 35 meters away, Ronaldinho basically takes all set kicks at the front of the penalty area, and his accuracy with his feet has also been praised by all parties. What's even more frightening is that the Brazilian king often doesn't need to run up when taking free kicks. He can complete all the steps with his lower legs, making it impossible for the opponent's goalkeeper to judge the path of the ball. Although the team lost in that game of the century, Ronaldinho's free kick that went around the wall gave La Liga's number one goalkeeper Casillas no time to react.
Classic replay: In 2004, Barcelona played against Real Sociedad at home. Barcelona was still trailing 0-1 until the 90th minute. Ronaldinho himself won a free kick in front of the penalty area. The distance was a bit close but the Brazilian shot it. The free kick also went straight to the lower left corner. The entire Camp Nou went crazy, not only for surpassing their old rival Real Madrid in the standings, but also for the arrival of their new king, and they could not suppress the excitement in their hearts.
Robert Carlos The unattractive little Brazilian Carlos has a magical left foot. His upper limbs are short, his thighs are thick and powerful, and his calf swings covertly and quickly. He relies on his powerful explosive power to take free kicks. Opponents will never dare to foul easily outside the penalty area, because people know that the kind of free kick taken by this wonder boy is almost the same as a penalty kick. In addition, Carlos seems to be learning the principle of grafting the ball in table tennis and snooker. The collision of a third party in the wall to change the direction of the ball and hit the goal sometimes makes people feel that he deliberately calculated it, so he does not need to bother. Avoiding the "human wall" blockage can directly test the rebound power of the "target". That free kick full of blood and domineering blood is the golden signature of this pocket golden left foot that dominates world football.
Classic replay: The earth-shattering 40-meter outspin missile that scored the French team's goal in the 1997 French Four Nations Football Invitational Tournament. After the game, the French newspaper was unable to explain how Carlos redirected the ball that flew toward the corner flag and hit it into the goal. They had to explain jokingly from a physics perspective: "According to Newton's third law, when an object moves to the right, when an object moves to the right, the force from the object The opposing wind speed will have the opposite effect on it.
Juninho is undoubtedly the biggest contributor to Lyon's incredible four consecutive league championships since joining the Ligue 1 team. With strict organization and scheduling, he has transformed into the leading midfield artist in France. At the same time, the Brazilian is also a top free kick master. According to statistics, one of his seven set kicks will go around the wall and spin into the goal. This probability is . How terrifying. Kahn should be the one who knows the Brazilian best. The German goalkeeper was humiliated by Juninho's free kick in the Champions League, and even the recognized top set-piece masters Assuncao and Carlos have been humiliated. He frankly admits that his compatriot's skills are better than his own. Juninho's free kick skills rely on talent, feeling and hard work. It has become his fixed habit to practice at least 20 free kicks after every training. In the national team, he still plays a supporting role, but in France, which advocates technical football, he is the absolute king.
Classic replay: Juninho’s 35-yard free kick in the Champions League directly broke through the gate guarded by Bremen goalkeeper Lineker. It is a classic that has been handed down from generation to generation and was recognized as the best goal scorer in the last Champions League. One of the goals, comparable to Ronaldinho's two magic goals that scored Chelsea and Garcia's goal against Juventus.
Mihajlovic's free kick volley from the outside of his left foot is Miha's specialty. The direct free kick shot within 40 meters from the goal is impeccable. Miha's free kick is powerful, a perfect work of art with a tricky angle and strong rotation. Moreover, when taking free kicks, he usually uses his calves to exert as much force as possible. The swing range of his thighs is very small, making it impossible for the goalkeeper to judge the path of the ball, making him unpredictable. "We have asked UEFA if we can use two goalkeepers when Mihajlovic takes a free kick, and I think that is the only way to stop him." Leverkusen played Lazio in the Champions League that year When the teams were placed in the same group, Daum, the team's meritorious coach, laughed at himself. "Misha's" free kick skills are unique in European football, and he is the holder of the record for scoring direct set kicks in the Apennines. Even when we think of Miha, almost the first impression is of a registered trademark free kick, and vice versa. It has almost become It has a conditioned reflex, and its accurate aim of "shooting without missing a beat" and sealing the throat with blood also makes opponents tremble.
Classic replay: In 1999, Mihajlovic scored three consecutive goals with direct free kicks against Sampdoria. It has created a historic feat that is unprecedented and will be rare in the future.
2. You can deflate the ball a little less, it is best to volley it easily out of the outside of the ball and kick it with the inner and outer instep. You can kick it a few times and find a knock on the door
3. The air pressure will be lower where the fluid velocity is higher, so the air pressure on the right side of the football is lower than the left side, creating a force to the right. As a result, as the football moves forward, it experiences a force pushing it to the right, causing a curved ball. It turns out that we often apply this principle in our daily life to change the direction of movement of objects in fluids. For example, the operation of airplanes and sailing boats is based on this principle.
4. Generally speaking, the kicking method of curve ball can be divided into several points: first, it is driven by the waist, which is why so many players have waist injuries~ second, the posture of swinging the legs~ third , the position where the ball touches the ball is, as my friend upstairs said, `middle and lower part. Of course, when the distance is far, you can move the ball touching point slightly upward!
The last point, of course, is your constant contact and practice.
By the way, don’t forget to relax your waist after practicing the arc!!!