full transcript

From the Ted Talk by Erez Garty: Football physics The "impossible" free kick

Unscramble the Blue Letters

In 1997, in a game between frcane and brzail, a young Brazilian player named Roberto claors 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 motoin, an ocbejt will move in the same direction and vitlceoy until a force is applied on it. When Carlos keickd 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 tcrik was in the spin. Carlos placed his kick at the lower right corner of the ball, sennidg it high and to the right, but also rotating around its axis. The ball started its flight in an aleraptpny direct rutoe, with air flwiong 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 dnfeiecfre made the ball curve towards the lower pressure zone. This phenomenon is called the Magnus ecefft. This type of kick, often referred to as a banana kick, is attempted reulgalry, and it is one of the elements that makes the biuefautl game beautiful. But crnvuig the ball with the pirescion needed to both bend around the wall and back into the goal is difficult. Too high and it saros 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 hkoos 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 tnneis 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 dteniafiferl in the surrounding air flow that curves it in the dieitrocn of the spin. And here's a qtsueoin. Could you theoretically kick a ball hard enough to make it bmaenoorg 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, ciasnug it to spiral into sllmaer 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.

Open Cloze

In 1997, in a game between ______ and ______, a young Brazilian player named Roberto ______ 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 ______, an ______ will move in the same direction and ________ until a force is applied on it. When Carlos ______ 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 _____ was in the spin. Carlos placed his kick at the lower right corner of the ball, _______ it high and to the right, but also rotating around its axis. The ball started its flight in an __________ direct _____, with air _______ 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 __________ made the ball curve towards the lower pressure zone. This phenomenon is called the Magnus ______. This type of kick, often referred to as a banana kick, is attempted _________, and it is one of the elements that makes the _________ game beautiful. But _______ the ball with the _________ needed to both bend around the wall and back into the goal is difficult. Too high and it _____ 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 _____ 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 ______ 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 ____________ in the surrounding air flow that curves it in the _________ of the spin. And here's a ________. Could you theoretically kick a ball hard enough to make it _________ 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, _______ it to spiral into _______ 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.

Solution

  1. beautiful
  2. question
  3. soars
  4. sending
  5. brazil
  6. carlos
  7. direction
  8. effect
  9. regularly
  10. causing
  11. kicked
  12. boomerang
  13. object
  14. hooks
  15. motion
  16. curving
  17. flowing
  18. tennis
  19. smaller
  20. france
  21. velocity
  22. difference
  23. trick
  24. route
  25. differential
  26. apparently
  27. precision

Original Text

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.

Frequently Occurring Word Combinations

ngrams of length 2

collocation frequency
air moved 2
magnus effect 2

Important Words

  1. air
  2. angle
  3. apparently
  4. applied
  5. applies
  6. area
  7. attempt
  8. attempted
  9. axis
  10. ball
  11. balls
  12. banana
  13. baseballs
  14. beautiful
  15. bend
  16. boomerang
  17. bounds
  18. brazil
  19. brazilian
  20. called
  21. carlos
  22. case
  23. causing
  24. circles
  25. corner
  26. creates
  27. creating
  28. curve
  29. curves
  30. curving
  31. decided
  32. defenders
  33. deflection
  34. difference
  35. differential
  36. difficult
  37. direct
  38. direction
  39. disintegrate
  40. documented
  41. early
  42. effect
  43. elements
  44. fast
  45. faster
  46. finally
  47. flight
  48. flow
  49. flowing
  50. flying
  51. force
  52. france
  53. free
  54. frisbees
  55. game
  56. gave
  57. goal
  58. goals
  59. golf
  60. good
  61. ground
  62. hard
  63. high
  64. history
  65. hit
  66. hits
  67. hooked
  68. hooks
  69. immortal
  70. impact
  71. impossible
  72. increase
  73. increased
  74. intercept
  75. isaac
  76. kick
  77. kicked
  78. late
  79. law
  80. left
  81. line
  82. luck
  83. magnificent
  84. magnus
  85. meter
  86. motion
  87. move
  88. moved
  89. named
  90. needed
  91. newton
  92. noticed
  93. object
  94. obstacles
  95. phenomenon
  96. physics
  97. player
  98. players
  99. playing
  100. precision
  101. pressure
  102. question
  103. reaches
  104. referred
  105. regularly
  106. roberto
  107. rotating
  108. route
  109. sadly
  110. score
  111. seemingly
  112. sending
  113. set
  114. side
  115. sides
  116. sir
  117. slow
  118. slowed
  119. slowing
  120. smaller
  121. soared
  122. soars
  123. spin
  124. spiral
  125. sport
  126. started
  127. stopping
  128. surrounding
  129. swerve
  130. tennis
  131. theoretically
  132. times
  133. trick
  134. type
  135. unassisted
  136. velocity
  137. wall
  138. wide
  139. young
  140. zone