Also known as "curve ball", a technical term for football. Refers to the kicking technique in which after the football is kicked, the ball moves forward in the air and moves in an arc. Curved kicks are often used when the attacking team gets a direct free kick near the opponent's penalty area and uses its curved running state to avoid the wall and score directly.

Principle of Banana Ball

Principle of Curved Ball: When the football is flying in the air and constantly rotating, because the air has a certain viscosity, 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, causing the football to fly forward in the air in an arc. Because the ball runs in an arc and is similar in shape to a banana, it is also commonly known as a "banana ball."

[Edit this paragraph] The secret of the banana ball

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 viscosity properties, 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 to the left in the horizontal direction and rotates clockwise around an axis parallel to the ground, 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 a variety of 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. Suppose you look 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 perpendicular to 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 from the side of the ball (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).

[Edit this paragraph] How to kick a "banana ball"

If you often watch football games, you must have seen a direct free kick in the penalty area. At this time, usually five or six defensive players form a "human wall" in front of the goal to block the goal path. The offensive team's kicker took a powerful shot. The ball bypassed the "human wall" and was about to fly out of the goal. However, it turned along the arc and went straight into the goal. The goalkeeper was caught off guard and watched helplessly. The ball went into the goal. This is the rather magical "banana ball".

Banana Ball Picture 1: The soccer ball moves horizontally without rotation (in this picture the ball is moving downwards) Picture 2: The soccer ball only rotates but does not move horizontally Picture 3 "Banana Wave" – the horizontal movement and rotation of the soccer ball Let's take a look at the attached picture first. The lines in the picture represent the air flow. Figure 1 represents the situation of a football moving horizontally without rotation. When the football moves forward, the air moves backward relative to the football. Figure 2 represents the situation where the football only rotates but does not move horizontally. When the football rotates, the surrounding air will be driven by the football, forming a whirlwind flow. Figure 3 represents the situation where horizontal motion and rotation exist at the same time, that is, the "banana wave" situation. At this time, the air flow speed on the right side of the football is greater than that on the left side. According to the Bernoulli equation (constant) of fluid mechanics, the air pressure will be lower where the fluid velocity is greater. Therefore, the air pressure on the right side of the football is lower than the left side, creating a rightward force. 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.

[Edit this paragraph] The active free kick master in world football

Beckham

Beckham may have the most expensive right foot in Europe , is good at taking penalties with the inside of his instep, and the ball flies towards the opponent's goal corner in a pleasing inward arc. 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 Pei's 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 pounds!

Ronaldinho

As the number one star in the world today, Ronaldinho’s free kick speed and arc are perfectly combined. In Gremio, , in Paris and Barcelona, ??people are used to him humiliating the opponent's goalkeeper with accurate half-high balls again and again. 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: Barcelona played Real Sociedad at home in 2004. 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's free kick also went straight. 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

Robert Carlos The 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. 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 France 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 repulsive wind speed will have the opposite effect on it.

Junior Juninho

Juninho Junior Lyon achieved an incredible four consecutive league championships. Juninho Junior is well-deserved. The biggest contributor. Since joining the Ligue 1 team, he has been good at rigorous organization and dispatching and 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, he takes set kicks every seven times. The probability of spinning around the wall and into the goal is so terrifying. Kahn should be the one who knows the Brazilians best. In the Champions League, the German goalkeeper was humiliated by Juninho's free kick. Top set-piece masters Assuncao and Carlos have frankly admitted that their compatriots' skills are better than their own. Juninho's free kick skills rely on talent, feeling and hard work. He has always practiced at least extra after every training. 20 free kicks have become his regular habit. Although he still plays a supporting role in the national team, in France, which advocates technical football, he is the absolute king. Classic replay: Juninho's 35 yards in the Champions League. The free kick directly broke through the gate guarded by Bremen goalkeeper Lineker and was regarded as a classic. It was recognized as one of the best goals in the last Champions League, comparable to Ronaldinho's goals against Chelsea and Garcia's goals against Juventus. Magic goal with the foot

Mihajlovic

Mihajlovic’s free kick volley from the outside of the left foot is Miha’s specialty, coming within 40 meters from the goal. Miha's direct free kick is impeccable. It is a perfect work of art with a combination of tricky angles and strong rotation. When taking the free kick, he usually uses his calves to exert as much force as possible, and his thighs swing very much. "We've asked UEFA if we can use two goalkeepers when Mihajlovic takes a free kick, and I think that's the only thing stopping him. method. "When Leverkusen was in the same group as Lazio in the UEFA Champions League, the team's meritorious coach Daum said self-deprecatingly. "Misha's free kick skills are unique in European football and are directly positioned for scoring in the Apennines. The record holder of the ball, even when we think of Miha, almost the first impression is the trademarked free kick, and vice versa, it has almost become a conditioned reflex, and his accurate shot that "doesn't miss the mark" also makes the opponent Terrified. Classic replay: In 1999, Mihajlovic scored three consecutive goals with a direct free kick, creating a historic feat that was unprecedented and rare.

[Edit this paragraph] The banana ball in table tennis

The "banana ball in table tennis" is a ball played with the backhand side twisting technique. This is a technique first used by European athletes. Now we Chinese athletes It is also widely used. It can give full play to the player's wrist strength and can more actively handle short balls in the table, creating opportunities for attacking.

[Edit this paragraph] Banana ball in snooker

The shot causes the cue ball to suddenly turn around the obstacle as it progresses.