full transcript

From the Ted Talk by Katerina Kaouri: The sonic boom problem

Unscramble the Blue Letters

Humans have been fascinated with speed for ages. The history of hmuan progress is one of ever-increasing velocity, and one of the most important achievements in this historical race was the breaking of the sound berairr. Not long after the first successful airplane flights, pilots were eager to push their planes to go faster and faster. But as they did so, increased turbulence and large forces on the plane pvereetnd them from aartineclceg further. Some tried to circumvent the problem through rsiky dives, often with tragic results. flnlaiy, in 1947, design improvements, such as a movable horizontal stabilizer, the all-moving tail, allowed an American military pilot nmaed Chuck Yeager to fly the Bell X-1 aircraft at 1127 km/h, becoming the first person to break the sound barrier and travel faster than the seped of sound. The Bell X-1 was the first of many supersonic aircraft to follow, with later designs reaching speeds over Mach 3. acrafirt traveling at supersonic speed create a shcok wave with a thunder-like noise known as a sonic boom, which can cause distress to people and animals below or even dagame buildings. For this reason, scientists around the world have been looking at sonic booms, trying to predict their path in the artmopehse, where they will land, and how loud they will be. To better understand how scientists study sonic booms, let's start with some basics of sound. Imagine trwhiong a small stone in a still pond. What do you see? The stone causes waves to travel in the water at the same speed in every direction. These circles that keep growing in radius are called wave fronts. Similarly, even though we cannot see it, a stationary sound source, like a home stereo, creates sunod wvaes tnvilraeg outward. The speed of the waves depends on factors like the altitude and temperature of the air they move through. At sea level, sound travels at about 1225 km/h. But instead of circles on a two-dimensional surface, the wave frntos are now concentric spheres, with the sound traveling along rays perpendicular to these waves. Now imagine a moving sound source, such as a train wlithse. As the source keeps monvig in a certain direction, the successive waves in front of it will become bunched closer together. This greater wave frequency is the cause of the famous Doppler eecfft, where approaching objects sound higher pcithed. But as long as the socrue is moving slower than the sound waves themselves, they will remain nested within each other. It's when an object goes supersonic, moving faster than the sound it makes, that the picture changes dramatically. As it oetekvars sound waves it has emitted, while generating new ones from its current position, the waves are forced together, forming a Mach cone. No sound is hared as it approaches an observer because the object is traveling faster than the sound it produces. Only after the object has passed will the observer hear the sonic boom. Where the Mach cone meets the gunrod, it forms a hyperbola, leaving a trail known as the boom carpet as it travels forward. This makes it possible to determine the area affected by a sonic boom. What about fgnriiug out how strong a sionc boom will be? This involves svoinlg the famous Navier-Stokes equations to find the variation of pressure in the air due to the srnupsoiec aircraft flying through it. This reutsls in the pressure sargutine known as the N-wave. What does this sphae mean? Well, the sonic boom occurs when there is a sudden cghnae in pressure, and the N-wave ilvnevos two booms: one for the initial prrusese rise at the aircraft's nose, and another for when the tail pseass, and the pressure suddenly returns to normal. This causes a dluobe boom, but it is usually heard as a single boom by human ears. In practice, computer models using these principles can often predict the lacotoin and iisnttney of sonic booms for given atmospheric conditions and flight trajectories, and there is oognnig raersceh to mitigate their effects. In the meantime, supersonic flight over land rimnaes prohibited. So, are sonic booms a recent creation? Not exactly. While we try to find ways to silence them, a few other animals have been using sonic booms to their avdaatgne. The gigantic Diplodocus may have been capable of cracking its tail fetsar than sound, at over 1200 km/h, possibly to deter predators. Some types of shrimp can also create a similar shock wave uaweendrtr, stunning or even knlilig pray at a distance with just a snap of their oversized claw. So while we hamuns have made great progress in our relentless pursuit of speed, it trnus out that nature was there first.

Open Cloze

Humans have been fascinated with speed for ages. The history of _____ progress is one of ever-increasing velocity, and one of the most important achievements in this historical race was the breaking of the sound _______. Not long after the first successful airplane flights, pilots were eager to push their planes to go faster and faster. But as they did so, increased turbulence and large forces on the plane _________ them from ____________ further. Some tried to circumvent the problem through _____ dives, often with tragic results. _______, in 1947, design improvements, such as a movable horizontal stabilizer, the all-moving tail, allowed an American military pilot _____ Chuck Yeager to fly the Bell X-1 aircraft at 1127 km/h, becoming the first person to break the sound barrier and travel faster than the _____ of sound. The Bell X-1 was the first of many supersonic aircraft to follow, with later designs reaching speeds over Mach 3. ________ traveling at supersonic speed create a _____ wave with a thunder-like noise known as a sonic boom, which can cause distress to people and animals below or even ______ buildings. For this reason, scientists around the world have been looking at sonic booms, trying to predict their path in the __________, where they will land, and how loud they will be. To better understand how scientists study sonic booms, let's start with some basics of sound. Imagine ________ a small stone in a still pond. What do you see? The stone causes waves to travel in the water at the same speed in every direction. These circles that keep growing in radius are called wave fronts. Similarly, even though we cannot see it, a stationary sound source, like a home stereo, creates _____ _____ _________ outward. The speed of the waves depends on factors like the altitude and temperature of the air they move through. At sea level, sound travels at about 1225 km/h. But instead of circles on a two-dimensional surface, the wave ______ are now concentric spheres, with the sound traveling along rays perpendicular to these waves. Now imagine a moving sound source, such as a train _______. As the source keeps ______ in a certain direction, the successive waves in front of it will become bunched closer together. This greater wave frequency is the cause of the famous Doppler ______, where approaching objects sound higher _______. But as long as the ______ is moving slower than the sound waves themselves, they will remain nested within each other. It's when an object goes supersonic, moving faster than the sound it makes, that the picture changes dramatically. As it _________ sound waves it has emitted, while generating new ones from its current position, the waves are forced together, forming a Mach cone. No sound is _____ as it approaches an observer because the object is traveling faster than the sound it produces. Only after the object has passed will the observer hear the sonic boom. Where the Mach cone meets the ______, it forms a hyperbola, leaving a trail known as the boom carpet as it travels forward. This makes it possible to determine the area affected by a sonic boom. What about ________ out how strong a _____ boom will be? This involves _______ the famous Navier-Stokes equations to find the variation of pressure in the air due to the __________ aircraft flying through it. This _______ in the pressure _________ known as the N-wave. What does this _____ mean? Well, the sonic boom occurs when there is a sudden ______ in pressure, and the N-wave ________ two booms: one for the initial ________ rise at the aircraft's nose, and another for when the tail ______, and the pressure suddenly returns to normal. This causes a ______ boom, but it is usually heard as a single boom by human ears. In practice, computer models using these principles can often predict the ________ and _________ of sonic booms for given atmospheric conditions and flight trajectories, and there is _______ ________ to mitigate their effects. In the meantime, supersonic flight over land _______ prohibited. So, are sonic booms a recent creation? Not exactly. While we try to find ways to silence them, a few other animals have been using sonic booms to their _________. The gigantic Diplodocus may have been capable of cracking its tail ______ than sound, at over 1200 km/h, possibly to deter predators. Some types of shrimp can also create a similar shock wave __________, stunning or even _______ pray at a distance with just a snap of their oversized claw. So while we ______ have made great progress in our relentless pursuit of speed, it _____ out that nature was there first.

Solution

  1. figuring
  2. waves
  3. aircraft
  4. fronts
  5. advantage
  6. intensity
  7. results
  8. involves
  9. sonic
  10. atmosphere
  11. speed
  12. passes
  13. risky
  14. signature
  15. shape
  16. humans
  17. damage
  18. barrier
  19. research
  20. turns
  21. faster
  22. killing
  23. traveling
  24. pressure
  25. underwater
  26. double
  27. pitched
  28. moving
  29. throwing
  30. solving
  31. named
  32. ground
  33. shock
  34. overtakes
  35. prevented
  36. ongoing
  37. effect
  38. change
  39. remains
  40. human
  41. supersonic
  42. accelerating
  43. whistle
  44. location
  45. source
  46. heard
  47. finally
  48. sound

Original Text

Humans have been fascinated with speed for ages. The history of human progress is one of ever-increasing velocity, and one of the most important achievements in this historical race was the breaking of the sound barrier. Not long after the first successful airplane flights, pilots were eager to push their planes to go faster and faster. But as they did so, increased turbulence and large forces on the plane prevented them from accelerating further. Some tried to circumvent the problem through risky dives, often with tragic results. Finally, in 1947, design improvements, such as a movable horizontal stabilizer, the all-moving tail, allowed an American military pilot named Chuck Yeager to fly the Bell X-1 aircraft at 1127 km/h, becoming the first person to break the sound barrier and travel faster than the speed of sound. The Bell X-1 was the first of many supersonic aircraft to follow, with later designs reaching speeds over Mach 3. Aircraft traveling at supersonic speed create a shock wave with a thunder-like noise known as a sonic boom, which can cause distress to people and animals below or even damage buildings. For this reason, scientists around the world have been looking at sonic booms, trying to predict their path in the atmosphere, where they will land, and how loud they will be. To better understand how scientists study sonic booms, let's start with some basics of sound. Imagine throwing a small stone in a still pond. What do you see? The stone causes waves to travel in the water at the same speed in every direction. These circles that keep growing in radius are called wave fronts. Similarly, even though we cannot see it, a stationary sound source, like a home stereo, creates sound waves traveling outward. The speed of the waves depends on factors like the altitude and temperature of the air they move through. At sea level, sound travels at about 1225 km/h. But instead of circles on a two-dimensional surface, the wave fronts are now concentric spheres, with the sound traveling along rays perpendicular to these waves. Now imagine a moving sound source, such as a train whistle. As the source keeps moving in a certain direction, the successive waves in front of it will become bunched closer together. This greater wave frequency is the cause of the famous Doppler effect, where approaching objects sound higher pitched. But as long as the source is moving slower than the sound waves themselves, they will remain nested within each other. It's when an object goes supersonic, moving faster than the sound it makes, that the picture changes dramatically. As it overtakes sound waves it has emitted, while generating new ones from its current position, the waves are forced together, forming a Mach cone. No sound is heard as it approaches an observer because the object is traveling faster than the sound it produces. Only after the object has passed will the observer hear the sonic boom. Where the Mach cone meets the ground, it forms a hyperbola, leaving a trail known as the boom carpet as it travels forward. This makes it possible to determine the area affected by a sonic boom. What about figuring out how strong a sonic boom will be? This involves solving the famous Navier-Stokes equations to find the variation of pressure in the air due to the supersonic aircraft flying through it. This results in the pressure signature known as the N-wave. What does this shape mean? Well, the sonic boom occurs when there is a sudden change in pressure, and the N-wave involves two booms: one for the initial pressure rise at the aircraft's nose, and another for when the tail passes, and the pressure suddenly returns to normal. This causes a double boom, but it is usually heard as a single boom by human ears. In practice, computer models using these principles can often predict the location and intensity of sonic booms for given atmospheric conditions and flight trajectories, and there is ongoing research to mitigate their effects. In the meantime, supersonic flight over land remains prohibited. So, are sonic booms a recent creation? Not exactly. While we try to find ways to silence them, a few other animals have been using sonic booms to their advantage. The gigantic Diplodocus may have been capable of cracking its tail faster than sound, at over 1200 km/h, possibly to deter predators. Some types of shrimp can also create a similar shock wave underwater, stunning or even killing pray at a distance with just a snap of their oversized claw. So while we humans have made great progress in our relentless pursuit of speed, it turns out that nature was there first.

Frequently Occurring Word Combinations

ngrams of length 2

collocation frequency
sonic boom 4
sound waves 3
sonic booms 3
sound barrier 2
supersonic aircraft 2
shock wave 2
wave fronts 2
mach cone 2

Important Words

  1. accelerating
  2. achievements
  3. advantage
  4. affected
  5. ages
  6. air
  7. aircraft
  8. airplane
  9. allowed
  10. altitude
  11. american
  12. animals
  13. approaches
  14. approaching
  15. area
  16. atmosphere
  17. atmospheric
  18. barrier
  19. basics
  20. bell
  21. boom
  22. booms
  23. break
  24. breaking
  25. buildings
  26. bunched
  27. called
  28. capable
  29. carpet
  30. change
  31. chuck
  32. circles
  33. circumvent
  34. claw
  35. closer
  36. computer
  37. concentric
  38. conditions
  39. cone
  40. cracking
  41. create
  42. creates
  43. creation
  44. current
  45. damage
  46. depends
  47. design
  48. designs
  49. deter
  50. determine
  51. diplodocus
  52. direction
  53. distance
  54. distress
  55. dives
  56. doppler
  57. double
  58. dramatically
  59. due
  60. eager
  61. ears
  62. effect
  63. effects
  64. emitted
  65. equations
  66. factors
  67. famous
  68. fascinated
  69. faster
  70. figuring
  71. finally
  72. find
  73. flight
  74. flights
  75. fly
  76. flying
  77. follow
  78. forced
  79. forces
  80. forming
  81. forms
  82. frequency
  83. front
  84. fronts
  85. generating
  86. gigantic
  87. great
  88. greater
  89. ground
  90. growing
  91. hear
  92. heard
  93. higher
  94. historical
  95. history
  96. home
  97. horizontal
  98. human
  99. humans
  100. hyperbola
  101. imagine
  102. important
  103. improvements
  104. increased
  105. initial
  106. intensity
  107. involves
  108. killing
  109. land
  110. large
  111. leaving
  112. level
  113. location
  114. long
  115. loud
  116. mach
  117. meets
  118. military
  119. mitigate
  120. models
  121. movable
  122. move
  123. moving
  124. named
  125. nature
  126. nested
  127. noise
  128. normal
  129. nose
  130. object
  131. objects
  132. observer
  133. occurs
  134. ongoing
  135. outward
  136. oversized
  137. overtakes
  138. passed
  139. passes
  140. path
  141. people
  142. perpendicular
  143. person
  144. picture
  145. pilot
  146. pilots
  147. pitched
  148. plane
  149. planes
  150. pond
  151. position
  152. possibly
  153. practice
  154. pray
  155. predators
  156. predict
  157. pressure
  158. prevented
  159. principles
  160. problem
  161. produces
  162. progress
  163. prohibited
  164. pursuit
  165. push
  166. race
  167. radius
  168. rays
  169. reaching
  170. reason
  171. relentless
  172. remain
  173. remains
  174. research
  175. results
  176. returns
  177. rise
  178. risky
  179. scientists
  180. sea
  181. shape
  182. shock
  183. shrimp
  184. signature
  185. silence
  186. similar
  187. similarly
  188. single
  189. slower
  190. small
  191. snap
  192. solving
  193. sonic
  194. sound
  195. source
  196. speed
  197. speeds
  198. spheres
  199. stabilizer
  200. start
  201. stationary
  202. stereo
  203. stone
  204. strong
  205. study
  206. stunning
  207. successful
  208. successive
  209. sudden
  210. suddenly
  211. supersonic
  212. surface
  213. tail
  214. temperature
  215. throwing
  216. tragic
  217. trail
  218. train
  219. trajectories
  220. travel
  221. traveling
  222. travels
  223. turbulence
  224. turns
  225. types
  226. understand
  227. underwater
  228. variation
  229. velocity
  230. water
  231. wave
  232. waves
  233. ways
  234. whistle
  235. world
  236. yeager