TedTest

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 human progress is one of ever-increasing velocity, and one of the most inatropmt achievements in this historical race was the breaking of the sound barrier. Not long after the first suufcscsel airplane flhgtis, 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 taigrc rutsels. Finally, in 1947, dsgien improvements, such as a movable horizontal siiazlebtr, 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 snsipeourc aircraft to follow, with later designs reaching speeds over Mach 3. acarfrit traveling at supersonic speed create a sochk wave with a thunder-like noise known as a sonic boom, which can cause distress to people and animals below or even damage blnduigis. For this raoesn, scientists around the world have been looking at sonic bomos, trying to pceirdt their path in the atmosphere, where they will land, and how loud they will be. To better understand how snstectiis study sonic booms, let's start with some basics of sound. Imagine throwing a small sonte 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 gwnirog in riduas are celald 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 cnioncrtec spheres, with the sound traveling along rays perpendicular to these waevs. Now imagine a moving sound source, such as a train whlstie. As the source keeps moving in a certain dciietron, 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 hhgier pihetcd. 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 obcejt is traveling faster than the sound it produces. Only after the object has passed will the obseervr hear the sonic boom. Where the Mach cone meets the ground, it forms a hyperbola, leaving a taril known as the boom carpet as it travels forward. This makes it possible to dietrmnee the area affetecd by a sonic boom. What about figuring out how strong a sonic boom will be? This involves solving the famous Navier-Stokes eiuoqants 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 psseas, and the pressure suddenly rtruens to normal. This causes a double boom, but it is usually hared as a single boom by human ears. In practice, cumtoepr mledos using these principles can often predict the location and intensity of sonic booms for given atmospheric conditions and flgiht trajectories, and there is ongoing research to mitigate their effects. In the meantime, supersonic flight over land remains prohibited. So, are sinoc 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 cakicrng its tail faster than sonud, at over 1200 km/h, plsbsioy to deter predators. Some types of shrimp can also create a similar shock wave underwater, stunning or even klinlig pray at a distance with just a snap of their oversized claw. So while we humans have made gaert progress in our relentless pursuit of speed, it turns out that nature was there first.

Open Cloze

Humans have been fascinated with speed for ages. The history of human progress is one of ever-increasing velocity, and one of the most _________ achievements in this historical race was the breaking of the sound barrier. Not long after the first __________ airplane _______, 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 ______ _______. Finally, in 1947, ______ improvements, such as a movable 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 __________ 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 damage _________. For this ______, scientists around the world have been looking at sonic _____, trying to _______ their path in the atmosphere, where they will land, and how loud they will be. To better understand how __________ study sonic booms, let's start with some basics of sound. Imagine throwing a small _____ 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 _______ in ______ are ______ 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 __________ spheres, with the sound traveling along rays perpendicular to these _____. Now imagine a moving sound source, such as a train _______. As the source keeps moving in a certain _________, 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 ______ _______. 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 ______ is traveling faster than the sound it produces. Only after the object has passed will the ________ 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 _________ the area ________ by a sonic boom. What about figuring out how strong a sonic boom will be? This involves solving the famous Navier-Stokes _________ 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 ______, and the pressure suddenly _______ to normal. This causes a double boom, but it is usually _____ as a single boom by human ears. In practice, ________ ______ using these principles can often predict the location and intensity of sonic booms for given atmospheric conditions and ______ trajectories, and there is ongoing research to mitigate their effects. In the meantime, supersonic flight over land remains prohibited. So, are _____ 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 ________ its tail faster than _____, at over 1200 km/h, ________ to deter predators. Some types of shrimp can also create a similar shock wave underwater, stunning or even _______ pray at a distance with just a snap of their oversized claw. So while we humans have made _____ progress in our relentless pursuit of speed, it turns out that nature was there first.

Solution

killing
sound
tragic
stabilizer
booms
object
flight
higher
models
cracking
affected
successful
computer
trail
concentric
predict
passes
buildings
design
possibly
aircraft
equations
whistle
stone
great
scientists
called
reason
pitched
supersonic
flights
sonic
radius
observer
important
direction
waves
determine
heard
returns
shock
results
growing

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
atmospheric
barrier
basics
bell
boom
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
prevented
principles
problem
produces
progress
prohibited
pursuit
push
race
radius
rays
reaching
reason
relentless
remain
remains
research
results
returns
rise
risky
scientists
sea
shape
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