D e s i gn i n g r ol l e r c oa s t e r s f or t h r i l

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Designing roller coasters for thrills and safety

When riding a roller coaster, you might feel the effects of acceleration. Roller coasters accelerate when they change speed or direction.Photo: anton5146/ Getty Images

They're diving, twisting, looping through the sky. Riders scream with delight as they're thrown

against their seat one moment and lifted into weightlessness the next. Though roller coasters may

seem scary, they are actually incredibly safe -- modern coasters are designed so that millions of

people can ride each year without any risk of injury. Balancing high-speed thrills with safety is part

of the complex process of designing a roller coaster.

From Zero To Max Speed

Like sports fans talking about the latest pitching legend or sprinting star, roller-coaster

enthusiasts can quote statistics about their favorite rides. They can list the tallest drop, greatest

vertical angle, and biggest roll. These are the elements that combine to give riders a feel of

adventure. What do they have in common? They're all measures of change.

Acceleration is change in speed. By itself, high speed isn't thrilling. It's acceleration that's exciting.

Think about flying in an airplane. While in the air, the airplane and all of the passengers are

moving hundreds of miles an hour, but the speed is constant, so no one notices. It gets boring after

By Rebecca E. F. Barone, Cricket Media on 02.26.20Word Count 1,059Level MAX


a while. Only on takeoff or landing, when speed quickly increases or decreases, does anyone realize

how fast they are moving. Roller coasters are designed with this in mind. By changing speed

quickly, roller coaster engineers make riders feel the speed.

There are many ways of creating these sensations, both through changes in absolute speed and

changes in direction of speed. The most easily recognized change in speed is the very first hill.

Taking off from a stop—going from zero to max speed—is what the first hill is all about. On the

other hand, loops and rolls are designed to change the direction of speed very quickly. Though

these elements are usually slower than the first hill, the change in direction causes a disorienting

change in acceleration.

Anatomy Of A Scream

Feeling pressed into your seat, or floating above it, are effects of acceleration too. Engineers use

the term "g-forces" to talk about these reactions to acceleration. This term describes acceleration

in relation to gravity. Walking around in an everyday environment, we're at 1 g, or experiencing

the usual effects of gravity.

When you accelerate in the same direction as gravity, it feels like you're weightless. "When your

body gets less than 1 g, it starts perceiving 'Hey! I'm falling!' And it automatically transmits a scare

factor to your entire body!" says Larry Giles, vice president for engineering at Busch Gardens

Williamsburg. This happens when you come up and over a hill on a roller coaster. Even if you're

holding on with white knuckles, you'll still feel yourself lift in the air.

When acceleration acts in the opposite direction as gravity, the extra force makes you feel heavier.

This is called "positive g's." A roller coaster changing direction from down one hill to up another

forces riders into their seats, pressing down with the extra g-force.

Often, engineers concentrate on maximizing the amount of time riders spend in a less-than-1-g

environment. Giles explains that positive-g situations are everyday occurrences. Something as

simple as stepping down a stair may lead to a momentary increase to 2 or 3 g's. But feeling

weightlessness is much more unfamiliar. And it's the unfamiliar, unexpected sensations that lead

to thrills.

Keeping A Careful Watch

All of these changes in speed make roller coasters exciting, but how much is too much? Engineers

have spent decades understanding the human body's response to acceleration. While highly

trained astronauts and fighter pilots can sustain 8 or 9 g's, the most that roller coasters create is 4

or 5 g's. Even then, it's only for a very short time.

From the start of planning a thrill ride, designers constantly analyze the g-force on riders at each

part of the ride. Powerful computer programs use a mathematical technique called finite element

analysis to examine how different forces affect riders. Engineers use these programs to look at the

magnitude of vertical, lateral, and fore-aft (front-back) g-forces as well as how these combine.

Every second of every ride must meet industry safety standards.

Redundant But Not Boring


Lifting you up, throwing you down, and flying from side to side—roller-coaster designers use many

specialized safety mechanisms to keep riders safe during the action! In fact, Jim Seay, owner of a

company that makes theme park rides, disagrees with the idea that there is a balance between

thrill and safety. "I wouldn't call it a balance, because safety trumps everything. It's intertwined in

every element you have." Not only is safety part of every feature, but every safety element is also

redundant. That means one part could fail completely, and there would still be backups to make

sure that everything worked as needed.

Lap bars and shoulder restraints are two of the most obvious safety features of a roller coaster, but

what most people don't realize is just how secure these are. "The mechanism inside has multiple

locks. So, if you have a failure of a lock, you have additional as backup," says Seay. Even if one lock

fails, backup locks ensure the rider never notices. What the rider sees as one safety mechanism—

one shoulder restraint or one lap bar—is actually several locking mechanisms under one cover.

"Safety is layered," he explains, meaning that backups to the backups are standard practice. It's

not only shoulder harness and lap belts keeping you safe -- engineers factor safety into every

feature.

Even the computer programs and electronics that run the ride are designed to put safety first.

"There is tremendous redundancy in the processors that are looking at all the conditions of the

ride," says Seay. If the results from these processors ever differ, the program will halt all the trains

on the tracks. "We can shut things down very easily. Coasters will come to a stop at a predicted

stopping location." Multiple systems compare data and stop cars before a problem becomes an

emergency.

A Fusion Of Joy And Safety

Everything about a modern coaster is designed to give riders a sensation of thrills and chills while

keeping them safe. From designing the g-forces within acceptable limits to redundant safety

mechanisms throughout the ride, engineers meticulously plan out every surge of adrenaline. With

the combination of safety and adventure, riders can scream without worry!


Quiz

1 According to the article, why do engineers want to maximize the amount of time riders spend in a less-than-1-g environment?

(A) because less than 1 g makes roller coaster riders feel comfortable by increasing a heavy sensation

(B) because less than 1 g gives roller coaster riders an unfamiliar thrill by making them feel weightless

(C) because anything higher than 1 g will not allow roller coaster riders to feel acceleration or velocity

(D) because anything higher than 1 g cannot be tolerated by the bodies of most roller coaster riders

2 Why is every safety element redundant and layered on roller coasters?

(A) Safety features are designed by computers, and these overestimate the danger of g-forces for riders.

(B) Safety features make roller coaster riders uncomfortable, so they are often hidden under largercushions.

(C) Safety is the most important goal, so if one part fails there are extra parts to make sure everything stillworks.

(D) Safety is often ignored by roller coaster riders, and engineers worry about them unlocking their lap bars.

3 Read the introduction of the article [paragraph 1].

How does the introduction develop the MAIN idea?

(A) It provides a vivid description of the experience of being on roller coasters, and contrasts their thrills withtheir safety.

(B) It provides an anecdote about a dangerous experience on a roller coaster, and explains how it causeddesign to change.

(C) It summarizes the physical forces at work on a roller coaster, and notes how they cause problems forengineers.

(D) It summarizes the number of people who ride roller coasters each year, and the effect of this on thepopularity of roller coasters.

4 What is the MAIN reason the author includes the section "From Zero To Max Speed"?

(A) to describe the speed of the tallest drops on roller coasters

(B) to emphasize the need for speed to get people off the ground

(C) to highlight the similar speeds of airplanes and roller coasters

(D) to introduce the contrasting effects of speed and acceleration


Answer Key

1 According to the article, why do engineers want to maximize the amount of time riders spend in a less-than-1-g environment?

(A) because less than 1 g makes roller coaster riders feel comfortable by increasing a heavy sensation

(B) because less than 1 g gives roller coaster riders an unfamiliar thrill by making them feelweightless

(C) because anything higher than 1 g will not allow roller coaster riders to feel acceleration or velocity

(D) because anything higher than 1 g cannot be tolerated by the bodies of most roller coaster riders

2 Why is every safety element redundant and layered on roller coasters?

(A) Safety features are designed by computers, and these overestimate the danger of g-forces for riders.

(B) Safety features make roller coaster riders uncomfortable, so they are often hidden under largercushions.

(C) Safety is the most important goal, so if one part fails there are extra parts to make sureeverything still works.

(D) Safety is often ignored by roller coaster riders, and engineers worry about them unlocking their lap bars.

3 Read the introduction of the article [paragraph 1].

How does the introduction develop the MAIN idea?

(A) It provides a vivid description of the experience of being on roller coasters, and contrasts theirthrills with their safety.

(B) It provides an anecdote about a dangerous experience on a roller coaster, and explains how it causeddesign to change.

(C) It summarizes the physical forces at work on a roller coaster, and notes how they cause problems forengineers.

(D) It summarizes the number of people who ride roller coasters each year, and the effect of this on thepopularity of roller coasters.

4 What is the MAIN reason the author includes the section "From Zero To Max Speed"?

(A) to describe the speed of the tallest drops on roller coasters

(B) to emphasize the need for speed to get people off the ground

(C) to highlight the similar speeds of airplanes and roller coasters

(D) to introduce the contrasting effects of speed and acceleration


Build a rubber band-powered car

Key concepts

Physics

Potential energy

Kinetic energy

Conservation of energy

Simple machine

Introduction

Admit it, you've probably launched a rubber band at least once — pulled one end back, and let it go

flying. Did you ever suspect that rubber bands could also be a fun way to learn about physics and

engineering? Find out in this project where you'll build a rubber band–powered car.

Background

By Ben Finio, Scientific American on 01.06.20Word Count 1,193Level MAX


When you stretch a rubber band it stores potential energy. Specifically it stores elastic potential

energy -- the type of energy stored when a material is deformed (as opposed to gravitational

potential energy, the type you get when you raise an object off the ground). When you release it all,

that stored energy has to go somewhere. If you launch a rubber band across the room, the

potential energy is converted to kinetic energy, the energy of motion.

But what about putting all that stored energy to use? You can attach your rubber band to a simple

machine — a wheel and axle — to build a simple rubber band–powered car. In real cars, gasoline's

chemical energy or the electrical energy in a battery is converted to kinetic energy of the moving

car. Your model car will use a rubber band as the source of energy. It will take a little engineering

to get your vehicle working — challenge yourself to see how far your car can go!

Materials

(Note: This is an engineering design project. The following is a suggested list of materials, but you

can substitute different ones.)

Corrugated cardboard

Two drinking straws

Two wooden skewers

Four CDs (that are OK to get scratched)

Sponge

Paper clip

Assorted rubber bands

Tape

Scissors

Flat, hard surface for testing your car

Hot-glue gun (optional)

Preparation

Carefully cut a piece of corrugated cardboard that is slightly longer and wider than the length of

one straw.

Tape the two straws to the cardboard, parallel to each other, one at each end.

Cut a rectangular notch in the cardboard on one end, about one inch by one inch. This will also cut

a segment out of the middle of one of the straws.

Insert a wooden skewer through each straw. These will be your car's axles.

Cut four small squares from the sponge and carefully press them onto the ends of the skewers.

Attach CDs to the axles to form wheels. Do this by stuffing a piece of sponge into the hole in the

middle of the CD, then using tape to secure the CD and prevent it from wobbling.


Make sure your car can roll smoothly. Put it down on a flat surface and give it a push. If necessary,

adjust the wheels so they are all parallel and don't wobble. How far do you think your car will go

when you power it with elastic rubber band energy?

Procedure

Loop a rubber band through itself around the middle,

exposed part of the wooden skewer (where you cut out

a notch in the cardboard and straw).

Tape the rubber band to the skewer to prevent it from

slipping — when the skewer rotates, the rubber band

should rotate with it.

Cut a small slot in the middle of the piece of cardboard.

Hook a paper clip through the slot.

Hook the free end of the rubber band onto the paper clip.

Wind up the axle that's connected to the rubber band. If necessary, pinch the rubber band on the

axle when you start, to prevent it from slipping.

Put your car down and release the axle. What happens? Does your car move forward? How far

does it go?

If your car didn't move, it's time for some troubleshooting.

If the rubber band didn't unwind at all, wind it more tightly and try again. You can also try

changing the location of the slot for the paper clip to adjust the rubber band's tightness. If the

rubber band unwound but the axle didn't spin, then the rubber band might not have been attached

securely enough to the skewer. Try attaching it to the skewer by tying a tight knot or using hot

glue.

If the wheels spun but the car didn't move forward at all, there might not have been enough

friction between the CDs and the ground. Try using the car on a different surface. If that still

doesn't work, try giving your CDs more grip by stretching rubber bands around them or by putting

a bead of hot glue along the edges. (Let the glue dry completely before you test your car again.)

Keep experimenting with your car. Make small changes to it and test it again. How far can you get

the car to go?

Extra: Think of the "fuel economy" for your rubber band–powered car. Gasoline-powered cars

calculate their fuel economy in miles per gallon, or how many miles the car can travel on one

gallon of fuel. Your car uses a stretched rubber band as the energy source instead of gasoline. How

could you measure the "fuel economy" for different designs? For example how many feet can your

car travel per initial windup rotation of the axle? How does this change with different rubber

bands or different paper clip positions? What gives you the best fuel economy?

Extra: Test different types of rubber bands to power your car. Does it work better with long or

short ones? Thick or thin ones?


Extra: Try using different materials to build your car. What happens if you use bottle caps instead

of CDs for wheels or pencils instead of skewers for axles?

Extra: Do this project with friends or family. Everyone can build their own car and then see whose

can go the farthest.

Extra: You can build a car powered by a balloon instead of a rubber band. See the "More to

explore" section below for instructions.

Observations And Results

When you wind up the car's axle, you stretch the rubber band and store potential energy. When

you release it, the rubber band starts to unwind, and the potential energy is converted to kinetic

energy as the car is propelled forward. The more you stretch the rubber band, the more potential

energy is stored, and the farther and faster the car should go.

That all sounds great in theory — but in practice you might have found it difficult. Several things

can prevent your car from working well. If the wheels are not aligned properly, they can wobble or

jam and prevent the car from rolling smoothly. The rubber band can slip relative to the wooden

axle, preventing the wheels from spinning. Even if the wheels do spin, there might not be enough

friction with the ground, causing them to spin in place without moving the car. These are all

challenges you can overcome with a little engineering effort!


Quiz

1 According to the article, why does the rubber band make the car move?

(A) because winding or stretching the rubber band creates potential energy that is changed into kineticenergy when the rubber band is released

(B) because pulling the rubber band to the bottom of the car increases gravitational energy when the rubberband is raised off the ground

(C) because thickening or lengthening the rubber band creates momentum that adds to the amount ofpossible wind-up rotation of the axles

(D) because twisting the rubber band around the axle increases the fuel economy and allows the gasolineto work at making the car faster

2 How does adding hot glue to the edges of the CDs affect the car's motion?

(A) It helps the car move by forcing the skewers to spin more quickly.

(B) It helps the car move by increasing friction between the CDs and the ground.

(C) It stops the car from moving by allowing the axles to wobble more.

(D) It stops the car from moving by causing the CDs to stick to the ground.

3 Read the "Introduction."

How does this section introduce the MAIN idea?

(A) It illustrates the steps necessary for using a rubber band to make a model car move forward.

(B) It elaborates on the variety of materials needed when building a rubber band-powered car.

(C) It suggests that an everyday object can be used to illustrate concepts of physics and engineering.

(D) It demonstrates that students cause problems by playing with the rubber bands during experiments.

4 What is one reason why the author includes the information about extra tests the reader can do with the model car?

(A) to demonstrate what might cause some readers to use a balloon instead of a rubber band for theexperiment

(B) to illustrate that problems can occur in the experiment if readers fail to properly follow all instructions

(C) to encourage the reader to learn how changing the conditions or materials can affect the model carexperiment

(D) to compare the reader's results in the model car experiment with those of the author's friends and family


Answer Key

1 According to the article, why does the rubber band make the car move?

(A) because winding or stretching the rubber band creates potential energy that is changed intokinetic energy when the rubber band is released

(B) because pulling the rubber band to the bottom of the car increases gravitational energy when the rubberband is raised off the ground

(C) because thickening or lengthening the rubber band creates momentum that adds to the amount ofpossible wind-up rotation of the axles

(D) because twisting the rubber band around the axle increases the fuel economy and allows the gasolineto work at making the car faster

2 How does adding hot glue to the edges of the CDs affect the car's motion?

(A) It helps the car move by forcing the skewers to spin more quickly.

(B) It helps the car move by increasing friction between the CDs and the ground.

(C) It stops the car from moving by allowing the axles to wobble more.

(D) It stops the car from moving by causing the CDs to stick to the ground.

3 Read the "Introduction."

How does this section introduce the MAIN idea?

(A) It illustrates the steps necessary for using a rubber band to make a model car move forward.

(B) It elaborates on the variety of materials needed when building a rubber band-powered car.

(C) It suggests that an everyday object can be used to illustrate concepts of physics andengineering.

(D) It demonstrates that students cause problems by playing with the rubber bands during experiments.

4 What is one reason why the author includes the information about extra tests the reader can do with the model car?

(A) to demonstrate what might cause some readers to use a balloon instead of a rubber band for theexperiment

(B) to illustrate that problems can occur in the experiment if readers fail to properly follow all instructions

(C) to encourage the reader to learn how changing the conditions or materials can affect the modelcar experiment

(D) to compare the reader's results in the model car experiment with those of the author's friends and family


Near the earth's polar extreme, tundrasupports life in permafrost

A landscape of the Alaska Peninsula National Wildlife Refuge. Areas of the refuge are part of the tundra, a region known for being cold, dryand harsh. Photo by Karen Bollinger/Wikimedia Commons

Tundra ecosystems are treeless regions that are found in the Arctic and on the tops of mountains.

The tundra is one of Earth's many biomes. A biome is a large geographical area with certain plants,

animals and climate.

The tundra's climate is cold and windy, and rainfall is minimal. Snow covers the land for much of

the year, but summer brings bursts of wildflowers.

In the Arctic tundra, the average temperature is -34 to -6 degrees Celsius (-30 to 20 degrees

Fahrenheit). The summer growing season is just 50 to 60 days long. During this period, the sun

shines up to 24 hours a day.

Plants And Animals Have Survival Strategies

The alpine tundra, or mountain tundra, is home to mountain goats, sheep, marmots and birds.

These animals feed on low-lying plants and insects. Hardy flora, or plants, such as cushion plants

By National Geographic, adapted by Newsela staff on 01.02.20Word Count 588Level 1030L


survive in the mountain zones by growing in rock depressions, which are sunken areas of land. In

the rock depressions, the plants are warmer and sheltered from the wind.

The Arctic tundra is found in the regions around the North Pole. It also supports many animal

species, including Arctic foxes, polar bears, gray wolves, caribou, snow geese and musk oxen.

Plants and animals that live in the harsh conditions of the tundra are essentially clinging to life.

They are very sensitive to environmental changes, like reduced snow cover and warmer

temperatures brought on by global warming.

Climate Change Impacts Tundra Life

Global warming is causing major changes in the Arctic tundra. Global warming is caused by

humans burning too many fossil fuels. Fossil fuels are natural fuels like oil, gas and wood. Burning

them creates greenhouse gases, like carbon dioxide. Greenhouse gases trap solar energy in the

atmosphere, which creates heat and raises global temperatures. Global warming is part of a wider

range of trends that scientists call climate change.

The impacts of climate change on the tundra are broad and somewhat unpredictable. Animals that

are typically found further south, like the red fox, are moving north onto the tundra. Now, the red

fox is competing with the Arctic fox for food and territory. The long-term effects on the Arctic fox

are unknown.

Other tundra residents, such as the wolf spider, are growing bigger and thriving. Plants are

changing, too. Shrubs are getting taller, but this is contributing to declines of sensitive lichens. A

lichen is a plant-like organism that grows on rocks and trees. These are an important food source

for caribou and other animals. The land is also changing. Lakes and ponds are evaporating or

draining away.

Deterioration Of Permafrost

The Arctic permafrost is the literal foundation for much of the region's unique ecosystem.

Permafrost is a layer of frozen soil and dead plants that extends about 450 meters (1,476 feet)

below the Earth's surface. Today, the permafrost is deteriorating due to climate change.

In much of the Arctic, the permafrost is frozen year-round. But in the southern regions of the

Arctic, the surface layer above the permafrost melts during the summer, forming bogs and shallow

lakes that invite an explosion of animal life. Insects swarm around the bogs, and millions of

migrating birds come to feed on them.

With global warming, the fall freeze is coming later — and in some places, not at all. More of the

permafrost is melting in the southern Arctic, and shrubs and spruce trees that previously couldn't

grow on the permafrost now can take root. This could alter the habitat of native tundra animals.


Quiz

1 Which two of the following sentences from the article include central ideas of the article?

1. The summer growing season is just 50 to 60 days long.2. Plants and animals that live in the harsh conditions of the tundra are essentially clinging to

life.3. The impacts of climate change on the tundra are broad and somewhat unpredictable.4. Insects swarm around the bogs, and millions of migrating birds come to feed on them.

(A) 1 and 2

(B) 2 and 3

(C) 1 and 4

(D) 3 and 4

2 Which answer choice describes two central ideas of the article?

(A) The tundra is a treeless biome that supports animal and plant life. Global warming and melting of thepermafrost are causing many changes in the tundra.

(B) The tundra is a treeless biome that supports a lot of wildlife. The average temperature is only -34 to -6degrees Celsius.

(C) The Arctic tundra has many plants and animals. These include lichen, Arctic foxes, polar bears, graywolves, caribou, snow geese and musk oxen.

(D) The alpine tundra is found in mountain zones. It is home to mountain goats, sheep, marmots and birds.

3 What is one reason why the author includes information about the permafrost?

(A) to help the reader understand how the foundation for the tundra's ecosystem was formed

(B) to help explain how harmful global warming is for people living in the tundra

(C) to show that tundras are disappearing in many areas around the world

(D) to give an example of how climate change is altering the landscape of the tundra

4 What is the MAIN reason the author includes the section "Plants And Animals Have Survival Strategies"?

(A) to describe the length of the seasons in the tundra

(B) to list the most common animals living in the tundra

(C) to describe how wildlife adapts in the tundra

(D) to list the ways that climate change is hurting plants in the tundra


Answer Key

1 Which two of the following sentences from the article include central ideas of the article?

1. The summer growing season is just 50 to 60 days long.2. Plants and animals that live in the harsh conditions of the tundra are essentially clinging to

life.3. The impacts of climate change on the tundra are broad and somewhat unpredictable.4. Insects swarm around the bogs, and millions of migrating birds come to feed on them.

(A) 1 and 2

(B) 2 and 3

(C) 1 and 4

(D) 3 and 4

2 Which answer choice describes two central ideas of the article?

(A) The tundra is a treeless biome that supports animal and plant life. Global warming and meltingof the permafrost are causing many changes in the tundra.

(B) The tundra is a treeless biome that supports a lot of wildlife. The average temperature is only -34 to -6degrees Celsius.

(C) The Arctic tundra has many plants and animals. These include lichen, Arctic foxes, polar bears, graywolves, caribou, snow geese and musk oxen.

(D) The alpine tundra is found in mountain zones. It is home to mountain goats, sheep, marmots and birds.

3 What is one reason why the author includes information about the permafrost?

(A) to help the reader understand how the foundation for the tundra's ecosystem was formed

(B) to help explain how harmful global warming is for people living in the tundra

(C) to show that tundras are disappearing in many areas around the world

(D) to give an example of how climate change is altering the landscape of the tundra

4 What is the MAIN reason the author includes the section "Plants And Animals Have Survival Strategies"?

(A) to describe the length of the seasons in the tundra

(B) to list the most common animals living in the tundra

(C) to describe how wildlife adapts in the tundra

(D) to list the ways that climate change is hurting plants in the tundra


Containing contaminants and contagions

Image 1. Washing your hands is an easy way to stop germs from spreading. It helps to prevent other people from getting sick. Photo: NanoCreative/Science Source

It can start out as simple as a cough. An unsuspecting

passerby drifts a bit too close, inhaling infected

droplets. Not soon after, the contagion has spread to

the population at large, creating an outbreak.

Fortunately, there are numerous measures in place to

prevent and manage such catastrophes.

Nonpharmaceutical Interventions

The simplest measures, known as nonpharmaceutical interventions (NPIs), are forms of

prevention that require no vaccines or prescriptions. This includes staying home when you are sick

and washing your hands. These methods are particularly effective against pathogens that can be

spread through person-to-person contact. NPIs can be used in conjunction with other prevention

measures, such as vaccines, to strengthen an individual's chances of avoiding infection. Because

NPIs, like handwashing, are simple and inexpensive, they are the first line of defense for people,

and if a vaccine is not available, it may be the only prevention tool that individuals can use.

By National Geographic Society on 01.28.20Word Count 1,009Level MAX


Unfortunately, prevention methods do not always

work. If someone is affected by an infectious disease,

it is important for them to seek treatment as soon as

possible. The earlier treatment can begin, the quicker

an individual can be healed, reducing the potential for

the disease to spread to others. For example, treating

genital herpes through medication alongside condom

use reduces the chance of passing on the disease. In

some cases, it may be advisable to treat people who

have been in contact with the patient before they

begin showing symptoms.

Quarantine

Once health practitioners identify cases of disease, practitioners and health officials can take steps

to prevent further infections. The measures that experts take to stop the spread of disease vary and

depend on the pathogen in question. A common method for reducing the likelihood of disease

spread is through quarantine, which involves separating an individual who may have come into

contact with the infectious agent from other people.

The United States has a comprehensive quarantine system at ports and border crossings to limit

infectious diseases entering the country. There are 20 of these quarantine stations across the

United States, and they are staffed by the Centers for Disease Control and Prevention (CDC). The

CDC may quarantine any traveler suspected of carrying an infectious disease or they might opt to

send them to a hospital or home for confinement. The CDC also has the authority to issue a federal

quarantine, but this measure is rarely needed. Within state lines, it is up to the state to regulate

what agency has the authority to quarantine, though it is usually the local health authorities.

Isolation

Isolation is another method, distinct from quarantine, to prevent disease spread. During isolation,

a sick individual is separated from those who are not sick. This is in contrast to a quarantine,

which separates an individual who might have been exposed to the contagion, but is not exhibiting

symptoms. Similar to quarantines, the CDC has the authority to isolate an individual suspected of

carrying a contagious disease that would harm the public.

The exact procedures of both isolation and quarantine depend on the severity of the disease in

question. Chickenpox, for example, is highly contagious and can be passed through skin contact or

through the air. When infected, children are instructed to not attend school so they do not infect

their classmates. However, because the disease is relatively mild, those who are infected can be

isolated at home. On the other hand, more serious and deadly diseases, such as Ebola or measles,

may require intervention from the state. In such cases, it is illegal to break an isolation or

quarantine order. Additionally, severely ill individuals are likely to be isolated in a hospital setting.

Closing Public Spaces

Authorities may also choose to close public spaces to prevent the spread of disease. For example,

schools may shut down if there is an increase in influenza cases. While the CDC provides guidance

for more severe global outbreaks, it does not officially determine if schools should close for the flu;


instead it is up to the school. However, recent evidence suggests that school closures can help limit

exposure to the contagion and mitigate the spread of disease.

Food Recall

A different approach is needed if the contagion is spread through food ingestion. Food can be

recalled if it is mislabeled or if there is a physical contaminant, such as plastic, or to prevent the

spread of foodborne pathogens, such as salmonella. When an infectious agent contaminates food,

it is imperative to pull the food in question off the shelves, thereby preventing more individuals

from getting sick after consuming tainted food.

The U.S. Food and Drug Administration (FDA) is responsible for regulating most food products,

except for meat, poultry, and some egg products, which are regulated by the U.S. Department of

Agriculture's Food Safety Inspection Service (FSIS). However, when there is a foodborne illness,

the CDC launches an investigation. Manufacturers and distributors can also contact the FDA or

FSIS with food-safety concerns. If the threat could seriously endanger the public, the FDA begins

to warn the public through the media.

Some foods are more prone to harboring pathogens than others. Although undercooked meat

often gets a bad reputation for being a source of bacteria, leafy greens, such as lettuce and spinach,

are more often responsible for foodborne illnesses. In 2018, romaine lettuce caused widespread

concern because of E. coli contamination. Fortunately, officials have taken action in light of recent

lettuce contaminations, including the 2011 Food Safety Modernization Act, which improves

sanitation standards. Additionally, modern advances in genetic sequencing technology are making

it easier for experts to track outbreaks and identify their source.

The methods used for containing disease are wide-ranging, and the methods that are employed

depend on what disease needs to be controlled. From the large-scale policies and procedures of

government agencies to individuals washing their hands, we all have a role to play in preventing

outbreaks.


Quiz

1 Read the following paragraph from the section "Quarantine."

The United States has a comprehensive quarantine system at ports and border crossings to limitinfectious diseases entering the country. There are 20 of these quarantine stations across theUnited States, and they are staffed by the Centers for Disease Control and Prevention (CDC).The CDC may quarantine any traveler suspected of carrying an infectious disease or they mightopt to send them to a hospital or home for confinement. The CDC also has the authority to issuea federal quarantine, but this measure is rarely needed. Within state lines, it is up to the state toregulate what agency has the authority to quarantine, though it is usually the local healthauthorities.

Which of the following can be inferred from the selection above?

(A) Diseases entering the United States from other counties are a threat to public health.

(B) Government intervention in disease control violates individual rights.

(C) Many travelers are quarantined at ports of entry each year.

(D) Controlling the spread of disease is always regulated by local agencies.

2 Read the following sentences from the article.

1. Similar to quarantines, the CDC has the authority to isolate an individual suspected ofcarrying a contagious disease that would harm the public.

2. When infected, children are instructed to not attend school so they do not infect theirclassmates.

3. However, recent evidence suggests that school closures can help limit exposure to thecontagion and mitigate the spread of disease.

4. However, when there is a foodborne illness, the CDC launches an investigation.

Which two sentences taken together provide the BEST evidence to support the idea that the federal government aims to protectpublic health?

(A) 1 and 2

(B) 2 and 3

(C) 3 and 4

(D) 1 and 4

3 Which of the following statements BEST represents the CDC’s approach toward infectious disease control in the article?

(A) It intervenes when state and local agencies fail to control outbreaks of disease.

(B) It promotes NPIs to prevent and control the spread of infectious diseases.

(C) It regulates food safety and investigates the sources of contaminated food.

(D) It controls the borders to prevent the entry of immigrants from suspected contagious regions.

4 Why did the author begin the article by describing the effectiveness of NPIs?

(A) to introduce the prevention of disease outbreaks before detailing steps taken after an outbreak

(B) to suggest disease outbreaks would not occur if people were more cautious

(C) to explain how medicines prescribed by health practitioners are effective in preventing diseaseoutbreaks

(D) to identify the measures that people should take to control contagious disease outbreaks


Answer Key

1 Read the following paragraph from the section "Quarantine."

The United States has a comprehensive quarantine system at ports and border crossings to limitinfectious diseases entering the country. There are 20 of these quarantine stations across theUnited States, and they are staffed by the Centers for Disease Control and Prevention (CDC).The CDC may quarantine any traveler suspected of carrying an infectious disease or they mightopt to send them to a hospital or home for confinement. The CDC also has the authority to issuea federal quarantine, but this measure is rarely needed. Within state lines, it is up to the state toregulate what agency has the authority to quarantine, though it is usually the local healthauthorities.

Which of the following can be inferred from the selection above?

(A) Diseases entering the United States from other counties are a threat to public health.

(B) Government intervention in disease control violates individual rights.

(C) Many travelers are quarantined at ports of entry each year.

(D) Controlling the spread of disease is always regulated by local agencies.


1. Similar to quarantines, the CDC has the authority to isolate an individual suspected ofcarrying a contagious disease that would harm the public.

2. When infected, children are instructed to not attend school so they do not infect theirclassmates.

3. However, recent evidence suggests that school closures can help limit exposure to thecontagion and mitigate the spread of disease.

4. However, when there is a foodborne illness, the CDC launches an investigation.

Which two sentences taken together provide the BEST evidence to support the idea that the federal government aims to protectpublic health?

(A) 1 and 2

(B) 2 and 3

(C) 3 and 4

(D) 1 and 4

3 Which of the following statements BEST represents the CDC’s approach toward infectious disease control in the article?

(A) It intervenes when state and local agencies fail to control outbreaks of disease.

(B) It promotes NPIs to prevent and control the spread of infectious diseases.

(C) It regulates food safety and investigates the sources of contaminated food.

(D) It controls the borders to prevent the entry of immigrants from suspected contagious regions.

4 Why did the author begin the article by describing the effectiveness of NPIs?

(A) to introduce the prevention of disease outbreaks before detailing steps taken after an outbreak

(B) to suggest disease outbreaks would not occur if people were more cautious

(C) to explain how medicines prescribed by health practitioners are effective in preventing diseaseoutbreaks

(D) to identify the measures that people should take to control contagious disease outbreaks



What's the difference between weather andclimate?

Weather events, like this hailstorm in Marion, Kansas, are not the same as the climate of a region. Image by Roger Hill/Science SourceImage by Roger Hill/Science Source

The overwhelming majority (97 percent) of scientists

agree that climate change is real, and that it is caused

by human activity. At the same time, however, we

have had some record-breaking cold winters.

In January 2019, a polar vortex plunged parts of

North America into Arctic conditions. It might seem counterintuitive, but cold weather events like

these do not disprove global warming. That's because weather and climate are two different

things.

Weather Refers To Short-term Conditions

Weather refers to the short-term conditions of the lower atmosphere, an area that begins at the

Earth's surface and extends up to 12 miles high. Weather conditions include precipitation,

By National Geographic Society, adapted by Newsela staff on 01.29.20Word Count 826Level 1180L


temperature, humidity, wind direction, wind speed, and atmospheric pressure. It could be sunny,

cloudy, rainy, foggy, cold, hot, windy, stormy or snowing.

The sun drives different types of weather by heating air in the lower atmosphere at varying rates.

Warm air rises and cold air rushes in to fill its place, causing wind. These winds, along with water

vapor in the air, influence the formation and movement of clouds, precipitation and storms.

The atmospheric conditions that influence weather are always changing, which is why the weather

is always changing. Meteorologists analyze data from satellites, weather stations, and buoys, which

are instruments that float in the ocean. The data help them predict weather conditions over the

upcoming days or weeks. Weather forecasts are very important. They warn people of dangerous

weather conditions, like big storms that can cause flash flooding or dry winds that can whip up

forest fires.

Climate Refers To Atmospheric Conditions

While weather refers to short-term changes in the lower atmosphere, climate refers to

atmospheric conditions over longer periods of time, usually 30 years or more. This is why it is

possible to have an especially cold spell even though, on average, global temperatures are rising.

The cold winter is a relatively small atmospheric change within a much larger, long-term trend of

warming.

Despite their differences, weather and climate are linked. As with weather, climate depends on

precipitation, wind speed and direction, humidity, and temperature. In fact, climate can be

thought of as an average of weather conditions over time. More importantly, a change in climate

can lead to changes in weather patterns.

Climate conditions vary in regions of the world and influence the types of plants and animals that

live there.

Fossil Fuel Use Has Increased Climate Change

Climate change is not a new concept. The global climate has changed many times over the course

of Earth's history. However, it is changing much faster now than it has in the past, and this time

human activities are to blame.

One of the leading factors contributing to climate change now is the burning of fossil fuels such as

coal, gas and oil, which we use for transport, energy production and industry. Burning fossil fuels

releases large amounts of carbon dioxide (CO2) into the atmosphere; CO2 is one of a group of

chemicals known as greenhouse gases. Greenhouse gases allow heat from the sun to enter the

atmosphere, but stop it from escaping, much like the glass of a greenhouse. The overall effect is

that the global temperature rises, leading to global warming.

Global warming is already affecting the planet as glaciers and Arctic sea ice are melting, sea levels

are rising, and there is an increased frequency and intensity of extreme weather events. The planet

has already warmed by about 0.8 degrees Celsius (1.4 degrees Fahrenheit) in the last century, and

temperatures have continued to rise. Animals and plants are moving to cooler areas.

Climate change makes extreme weather more likely. In 2018, at least 5,000 people were killed and

28.9 million more required aid as a result of extreme weather events like floods, wildfires,


hurricanes or typhoons. It is likely that more frequent and more severe weather events are on the

horizon.

Worldwide Efforts To Address Global Warming

Scientists first discovered and explained the physics of greenhouse gases in the early to mid-

1800s. In 1896, Swedish scientist Svante Arrhenius first proposed that humans could influence the

climate and cause global warming by releasing carbon dioxide into the atmosphere. In the late

1930s, scientists found that temperatures were already rising but it took until the 1980s for the

science to gain acceptance and for action to be taken.

In 1988, the global community came together to form the Intergovernmental Panel on Climate

Change (IPCC). Since then, leaders from around the world have agreed to a series of goals to lower

CO2 emissions to combat climate change. The latest is the 2015 Paris Agreement, in which 197

countries pledged to stop global temperatures from rising by more than 2 degrees Celsius (3.6

degrees Fahrenheit). All United Nations member states agreed to "take urgent action to combat

climate change and its impacts." In 2017, however, the United States, which releases the second-

largest amount of greenhouse gases in the world, announced it would withdraw from the

agreement.


Quiz


1. The sun drives different types of weather by heating air in the lower atmosphere at varyingrates.

2. The atmospheric conditions that influence weather are always changing, which is why theweather is always changing.

3. They warn people of dangerous weather conditions, like big storms that can cause flashflooding or dry winds that can whip up forest fires.

4. It is likely that more frequent and more severe weather events are on the horizon.

Which two sentences taken together provide the BEST evidence to support the idea that weather forecasts will become anincreasingly important tool for humans?

(A) 1 and 2

(B) 2 and 3

(C) 3 and 4

(D) 1 and 4

2 Is the author of the article suggesting that the global community has been too slow to address climate change? Which selectionfrom the article supports your answer?

(A) Yes; "Greenhouse gases allow heat from the sun to enter the atmosphere, but stop it from escaping,much like the glass of a greenhouse. The overall effect is that the global temperature rises, leading toglobal warming."

(B) Yes; "In 1896, Swedish scientist Svante Arrhenius first proposed that humans could influence theclimate and cause global warming by releasing carbon dioxide into the atmosphere. In the late 1930s,scientists found that temperatures were already rising but it took until the 1980s for the science to gainacceptance and for action to be taken."

(C) No; "In 1988, the global community came together to form the Intergovernmental Panel on ClimateChange (IPCC). Since then, leaders from around the world have agreed to a series of goals to lowerCO2 emissions to combat climate change. The latest is the 2015 Paris Agreement, in which 197countries pledged to stop global temperatures from rising by more than 2 degrees Celsius (3.6 degreesFahrenheit)."

(D) No; "All United Nations member states agreed to "take urgent action to combat climate change and itsimpacts." In 2017, however, the United States, which releases the second-largest amount ofgreenhouse gases in the world, announced it would withdraw from the agreement."

3 How does the author connect weather with climate?

(A) The author illustrates the effects of each on specific animals and their natural habitats.

(B) The author highlights the evidence that shows historic changes in the weather and climate.

(C) The author outlines and explores the differences in weather and climate of various places on Earth.

(D) The author defines and explains the factors that influence each and how they affect each other.

4 Why does the author begin the article by highlighting the January 2019 polar vortex?

(A) to introduce and dispel the notion that cold weather events disprove global warming

(B) to introduce and explain the reasons why people burn fossil fuels for heat and energy

(C) to suggest that climate change is already well-controlled by the Paris Agreement

(D) to suggest that a majority of scientists were shocked by the record-breaking cold


Answer Key


1. The sun drives different types of weather by heating air in the lower atmosphere at varyingrates.

2. The atmospheric conditions that influence weather are always changing, which is why theweather is always changing.

3. They warn people of dangerous weather conditions, like big storms that can cause flashflooding or dry winds that can whip up forest fires.

4. It is likely that more frequent and more severe weather events are on the horizon.

Which two sentences taken together provide the BEST evidence to support the idea that weather forecasts will become anincreasingly important tool for humans?

(A) 1 and 2

(B) 2 and 3

(C) 3 and 4

(D) 1 and 4

2 Is the author of the article suggesting that the global community has been too slow to address climate change? Which selectionfrom the article supports your answer?

(A) Yes; "Greenhouse gases allow heat from the sun to enter the atmosphere, but stop it from escaping,much like the glass of a greenhouse. The overall effect is that the global temperature rises, leading toglobal warming."

(B) Yes; "In 1896, Swedish scientist Svante Arrhenius first proposed that humans could influencethe climate and cause global warming by releasing carbon dioxide into the atmosphere. In thelate 1930s, scientists found that temperatures were already rising but it took until the 1980s forthe science to gain acceptance and for action to be taken."

(C) No; "In 1988, the global community came together to form the Intergovernmental Panel on ClimateChange (IPCC). Since then, leaders from around the world have agreed to a series of goals to lowerCO2 emissions to combat climate change. The latest is the 2015 Paris Agreement, in which 197countries pledged to stop global temperatures from rising by more than 2 degrees Celsius (3.6 degreesFahrenheit)."

(D) No; "All United Nations member states agreed to "take urgent action to combat climate change and itsimpacts." In 2017, however, the United States, which releases the second-largest amount ofgreenhouse gases in the world, announced it would withdraw from the agreement."

3 How does the author connect weather with climate?

(A) The author illustrates the effects of each on specific animals and their natural habitats.

(B) The author highlights the evidence that shows historic changes in the weather and climate.

(C) The author outlines and explores the differences in weather and climate of various places on Earth.

(D) The author defines and explains the factors that influence each and how they affect each other.

4 Why does the author begin the article by highlighting the January 2019 polar vortex?

(A) to introduce and dispel the notion that cold weather events disprove global warming

(B) to introduce and explain the reasons why people burn fossil fuels for heat and energy

(C) to suggest that climate change is already well-controlled by the Paris Agreement

(D) to suggest that a majority of scientists were shocked by the record-breaking cold

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