In 1997, in a game between France and Brazil, a young Brazilian player named Roberto Carlos set up for a 35 meter free kick. With no direct line to the goal, Carlos decided to attempt the seemingly impossible. His kick sent the ball flying wide of the players, but just before going out of bounds, it hooked to the left and soared into the goal. According to Newton's first law of motion, an object will move in the same direction and velocity until a force is applied on it. When Carlos kicked the ball, he gave it direction and velocity, but what force made the ball swerve and score one of the most magnificent goals in the history of the sport? The trick was in the spin. Carlos placed his kick at the lower right corner of the ball, sending it high and to the right, but also rotating around its axis. The ball started its flight in an apparently direct route, with air flowing on both sides and slowing it down. On one side, the air moved in the opposite direction to the ball's spin, causing increased pressure, while on the other side, the air moved in the same direction as the spin, creating an area of lower pressure. That difference made the ball curve towards the lower pressure zone. This phenomenon is called the Magnus effect. This type of kick, often referred to as a banana kick, is attempted regularly, and it is one of the elements that makes the beautiful game beautiful. But curving the ball with the precision needed to both bend around the wall and back into the goal is difficult. Too high and it soars over the goal. Too low and it hits the ground before curving. Too wide and it never reaches the goal. Not wide enough and the defenders intercept it. Too slow and it hooks too early, or not at all. Too fast and it hooks too late. The same physics make it possible to score another apparently impossible goal, an unassisted corner kick. The Magnus effect was first documented by Sir Isaac Newton after he noticed it while playing a game of tennis back in 1670. It also applies to golf balls, frisbees and baseballs. In every case, the same thing happens. The ball's spin creates a pressure differential in the surrounding air flow that curves it in the direction of the spin. And here's a question. Could you theoretically kick a ball hard enough to make it boomerang all the way around back to you? Sadly, no. Even if the ball didn't disintegrate on impact, or hit any obstacles, as the air slowed it, the angle of its deflection would increase, causing it to spiral into smaller and smaller circles until finally stopping. And just to get that spiral, you'd have to make the ball spin over 15 times faster than Carlos's immortal kick. So good luck with that.
1997年,在一场法国与巴西之间的比赛中 一名叫Robert Carlos的年轻巴西球员 从35米外发了任意球 没有任何通向球门的直线 Carlos的尝试看起来是不可能 他的射门让球飞过球员, 但是就当球要出界时,它向左勾 然后进门 根据牛顿的第一定律 一个物体会以同样的方向和矢量移动 除非一个力被施加 但Carlos踢球时,他已经给球速度和矢量了 但是是什么力让球改变方向 然后成为运动史以来最伟大的进球之一? 诀窍是旋转 Carlos从右下方踢球 让球边绕轴心旋转,边向右侧高飞 球从一个明显的直线起飞 空气飞过两边使其变慢 在一边,空气以球转的反方向旋转 导致压力上升 然而在另一边,空气以与球相同的方向旋转 产生一部分低压区 这个差异,使球向低压区弯曲 这个现象叫做马格纳斯效应 这种踢球,也被叫做香蕉球 被经常使用 而且它会让一场精彩的比赛更加精彩 但是香蕉球所需要的精准度 使其偏向墙然后进门,是非常困难的 太高的话球会飞过球门 太低的话会在旋转前击地 角度太大的话会永远进不了球门 角度不够大的话 防守者就可以拦截 太慢的话球会早转弯,甚至不转 太快的话球会转的太晚 同样的物理理论 使一个看起来不可能,没有收到任何帮助的 的角球进球 马格纳斯效应最初是被伊萨克·牛顿所记录 在1670年,他打完一场网球后发现的 这个原理同样适应于高尔夫球,飞碟和棒球 在每个情况下,同样的事情总是发生 球的旋转产生环绕的气流气压不等 从而导致球向其旋转 又有一个问题了 从理论上来讲,你可以将球使劲踢 足以让球转回你吗? 可惜的是,不行 即使球没有在冲撞中解体 或者击中任何障碍物 空气使其变慢 偏转角会增加 使螺旋变成越来越小的圆 最终停止 只是达到旋转 你需要使球转的 比Carlos不朽的进球快15倍 那祝你好运