full transcript
From the Ted Talk by Katerina Kaouri: The sonic boom problem
Unscramble the Blue Letters
Humans have been fascinated with seped for ages. The hrtsoiy of human progress is one of ever-increasing veoclity, and one of the most important acnvhemeiets in this historical race was the breaking of the sound briaerr. Not long after the first successful airplane flights, plitos 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 rtusles. Finally, in 1947, design improvements, such as a mobvale horizontal saezbliitr, 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 disgnes 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 dgmaae bgldiunis. 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 udtserannd how setisnitcs study sonic booms, let's start with some basics of sound. Imagine trnhoiwg 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 raidus are caelld wave fronts. Similarly, even though we cannot see it, a siartotnay sound source, like a home stereo, creates sound waves traveling ourwtad. 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 sucfrae, 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 soucre keeps moving in a certain direction, the successive waves in front of it will become buehcnd closer together. This greater wave frequency is the cause of the famous deoplpr effect, where approaching objects sound higher pitched. But as long as the source is moving slower than the sound wveas themselves, they will remain nested within each other. It's when an object goes sspnieruoc, moving faster than the sunod it makes, that the picture changes dramatically. As it okvartees sound waves it has eitemtd, while generating new ones from its current position, the waves are forced together, forming a Mach cone. No sound is hread as it approaches an osvreber 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 tiral known as the boom carpet as it travels forward. This makes it possible to determine the area aecfetfd by a sonic boom. What about figuring out how strong a sonic boom will be? This involves solving the faomus Navier-Stokes equations to find the viraatoin 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 seddun 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 haumn ears. In practice, computer models using these principles can often predict the location and intensity of sinoc 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 bmoos a recent creation? Not exactly. While we try to find ways to silence them, a few other aanmils 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 dteer predators. Some types of shrimp can also create a similar shock wave underwater, stunning or even killing pray at a dsntcaie with just a snap of their oversized claw. So while we hmuans have made great progress in our rlentesels pursuit of speed, it truns out that nature was there first.
Open Cloze
Humans have been fascinated with _____ for ages. The _______ of human progress is one of ever-increasing ________, and one of the most important ____________ in this historical race was the breaking of the sound _______. Not long after the first successful airplane flights, ______ 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 _______. Finally, in 1947, design improvements, such as a _______ horizontal __________, 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 _______ 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 ______ _________. 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 __________ how __________ 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 ______ are ______ wave fronts. Similarly, even though we cannot see it, a __________ sound source, like a home stereo, creates sound waves traveling _______. 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 _______, 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 ______ keeps moving in a certain direction, the successive waves in front of it will become _______ closer together. This greater wave frequency is the cause of the famous _______ effect, where approaching objects sound higher pitched. But as long as the source is moving slower than the sound _____ themselves, they will remain nested within each other. It's when an object goes __________, moving faster than the _____ it makes, that the picture changes dramatically. As it _________ sound waves it has _______, while generating new ones from its current position, the waves are forced together, forming a Mach cone. No sound is _____ as it approaches an ________ 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 _____ known as the boom carpet as it travels forward. This makes it possible to determine the area ________ by a sonic boom. What about figuring out how strong a sonic boom will be? This involves solving the ______ Navier-Stokes equations to find the _________ 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 ______ 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 _____ ears. In practice, computer models using these principles can often predict the location and intensity of _____ 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 _____ a recent creation? Not exactly. While we try to find ways to silence them, a few other _______ 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 _____ predators. Some types of shrimp can also create a similar shock wave underwater, stunning or even killing pray at a ________ with just a snap of their oversized claw. So while we ______ have made great progress in our __________ pursuit of speed, it _____ out that nature was there first.
Solution
- results
- throwing
- observer
- achievements
- movable
- emitted
- turns
- overtakes
- pilots
- outward
- humans
- human
- variation
- bunched
- distance
- history
- surface
- trail
- scientists
- sudden
- source
- deter
- speed
- velocity
- relentless
- famous
- called
- heard
- animals
- doppler
- buildings
- designs
- stabilizer
- waves
- understand
- supersonic
- sound
- damage
- stationary
- radius
- barrier
- sonic
- affected
- booms
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
- accelerating
- achievements
- advantage
- affected
- ages
- air
- aircraft
- airplane
- allowed
- altitude
- american
- animals
- approaches
- approaching
- area
- atmosphere
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- basics
- bell
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- booms
- break
- breaking
- buildings
- bunched
- called
- capable
- carpet
- change
- chuck
- circles
- circumvent
- claw
- closer
- computer
- concentric
- conditions
- cone
- cracking
- create
- creates
- creation
- current
- damage
- depends
- design
- designs
- deter
- determine
- diplodocus
- direction
- distance
- distress
- dives
- doppler
- double
- dramatically
- due
- eager
- ears
- effect
- effects
- emitted
- equations
- factors
- famous
- fascinated
- faster
- figuring
- finally
- find
- flight
- flights
- fly
- flying
- follow
- forced
- forces
- forming
- forms
- frequency
- front
- fronts
- generating
- gigantic
- great
- greater
- ground
- growing
- hear
- heard
- higher
- historical
- history
- home
- horizontal
- human
- humans
- hyperbola
- imagine
- important
- improvements
- increased
- initial
- intensity
- involves
- killing
- land
- large
- leaving
- level
- location
- long
- loud
- mach
- meets
- military
- mitigate
- models
- movable
- move
- moving
- named
- nature
- nested
- noise
- normal
- nose
- object
- objects
- observer
- occurs
- ongoing
- outward
- oversized
- overtakes
- passed
- passes
- path
- people
- perpendicular
- person
- picture
- pilot
- pilots
- pitched
- plane
- planes
- pond
- position
- possibly
- practice
- pray
- predators
- predict
- pressure
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- principles
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- progress
- prohibited
- pursuit
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- research
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- scientists
- sea
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- shock
- shrimp
- signature
- silence
- similar
- similarly
- single
- slower
- small
- snap
- solving
- sonic
- sound
- source
- speed
- speeds
- spheres
- stabilizer
- start
- stationary
- stereo
- stone
- strong
- study
- stunning
- successful
- successive
- sudden
- suddenly
- supersonic
- surface
- tail
- temperature
- throwing
- tragic
- trail
- train
- trajectories
- travel
- traveling
- travels
- turbulence
- turns
- types
- understand
- underwater
- variation
- velocity
- water
- wave
- waves
- ways
- whistle
- world
- yeager