Physical Science

To the TeacherCritical Thinking/Problem Solving worksheets in this booklet exercise the students’ abilities to applythinking skills to situations related to concepts presented in the student edition. Students will applytheir knowledge to a new situation, analyze the new information, and synthesize in order to respondin a creative way. A series of responses that students might give are provided for you at the end ofthis booklet.

Glencoe/McGraw-Hill

Copyright © by the McGraw-Hill Companies, Inc. All rights reserved. Except as permission under the UnitedStates Copyright Act, no part of this publication may be reproduced or distributed in any form or by anymeans, or stored in a database or retrieval system, without the prior written permission of the publisher.

Send all inquiries to:Glencoe/McGraw-Hill8787 Orion PlaceColumbus, OH 43240

ISBN 0-07-825728-XPrinted in the United States of America1 2 3 4 5 6 7 8 9 10 009 06 05 04 03 02 01

Student EditionTeacher Wraparound EditionInteractive Teacher Edition CD-ROMInteractive Lesson Planner CD-ROMLesson PlansContent Outline for TeachingDirected Reading for Content MasteryFoldables: Reading and Study SkillsAssessment

Chapter ReviewChapter TestsExamView Pro Test Bank SoftwareAssessment TransparenciesPerformance Assessment in the Science

ClassroomThe Princeton Review Standardized Test

Practice BookletDirected Reading for Content Mastery in SpanishSpanish ResourcesGuided Reading Audio Program

ReinforcementEnrichmentActivity WorksheetsSection Focus TransparenciesTeaching TransparenciesLaboratory ActivitiesScience Inquiry LabsCritical Thinking/Problem SolvingReading and Writing Skill ActivitiesCultural DiversityLaboratory Management and Safety in the Science

ClassroomMindjogger Videoquizzes and Teacher GuideInteractive Explorations and Quizzes CD-ROMVocabulary Puzzlemaker SoftwareCooperative Learning in the Science ClassroomEnvironmental Issues in the Science ClassroomHome and Community InvolvementUsing the Internet in the Science Classroom

Glencoe Science

ii

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

iii

Table of Contents

To the Teacher . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii

Skills Correlation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv

Activities 1 Testing the Waters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2 Breaking All the Records . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

3 Power from Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

4 Discovering Hidden Planets . . . . . . . . . . . . . . . . . . . . . . . . . 4

5 New Insulation for Space Shuttles . . . . . . . . . . . . . . . . . . . . 5

6 The Appeal of Perpetual Motion Machines . . . . . . . . . . . . . 6

7 Stonehenge—An Engineering Marvel . . . . . . . . . . . . . . . . . 7

8 Energy-Saving Refrigerators . . . . . . . . . . . . . . . . . . . . . . . . . 8

9 Radon Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

10 What’s the difference? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

11 Ancient Mysteries and Carbon-14 Dating . . . . . . . . . . . . . . 11

12 Pollution Goes Undergound . . . . . . . . . . . . . . . . . . . . . . . . . 12

13 The Birth of an Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

14 Gasoline—Finding a New Formula . . . . . . . . . . . . . . . . . . . 14

15 Building Materials of the Future . . . . . . . . . . . . . . . . . . . . . 15

16 Acid Precipitation Report Card . . . . . . . . . . . . . . . . . . . . . . 16

17 Environmentally Friendly Cars . . . . . . . . . . . . . . . . . . . . . . . 17

18 Pole Reversal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

19 Patient-Friendly Cancer Treatment . . . . . . . . . . . . . . . . . . . 19

20 Regulating Nuclear Power Plants . . . . . . . . . . . . . . . . . . . . . 20

21 Supersonic Impact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

22 Treating Cancer with Light . . . . . . . . . . . . . . . . . . . . . . . . . . 22

23 Swimming with Sharks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Answer Key . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

iii

Critical ThinkingProblem Solving

iv

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Cla

rifyi

ng is

sues

Com

parin

g an

d co

ntra

stin

g

Dev

elop

ing

a pe

rspe

ctiv

e

Dis

tingu

ishi

ng r

elev

ant f

rom

irr

elev

ant f

acts

Dra

win

g co

nclu

sion

s

Eva

luat

ing

info

rmat

ion

Exa

min

ing

and

eval

uatin

g as

sum

ptio

nsE

xtra

pola

ting

data

/ in

form

atio

nG

ener

atin

g an

d as

sess

ing

solu

tions

Mak

ing

a hy

poth

esis

Mak

ing

pred

ictio

ns o

r in

terp

reta

tions

Mak

ing

judg

men

ts

Obs

ervi

ng a

nd in

ferr

ing

Rec

ogni

zing

cau

se

and

effe

ctS

umm

ariz

ing/

synt

hesi

zing

Act

ivit

y

Cri

tica

l Th

inki

ng

/ P

rob

lem

So

lvin

g S

kills

Co

rrel

atio

n

Ski

ll1

23

45

67

89

1011

1213

1415

1617

1819

2021

2223

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

1

1ActivityTesting the WatersProblem

Solving

No one knew why fish were dying in Oshkosh,Wisconsin. Every year, one or two major fish killsoccurred on the Fox River that flows through thetown. Fish kills are not unusual. They can becaused by natural events such as the stress ofspawning or lack of dissolved oxygen in the water.But, the number of fish being killed was so largethat something unnatural seemed to be the cause.

Searching for CluesScientists began to investigate. They tested thewater and the fish for known causes of fishkills—pesticides, herbicides, toxic waste, andtoxic metals. These substances were not causingthe problem, so scientists measured the level ofchlorine in the water. Chlorine was being usedto treat sewage at a water-treatment plantlocated near the river.

Researchers hung cages of live fish directly in the water-treatment plant’s discharge. Thefish lived, which indicated that chlorine fromthe water-treatment plant was not the cause ofthe problem.

The search continued. Scientists had noticedan outboard motor plant across from the water-treatment plant a few hundred meters down-stream. They found that the plant tested its newoutboard motors in the river, running severalmotors at once. Outboard motors vent theirexhaust into the water to muffle the noise.

Scientists hypothesized that the carbonmonoxide coming from the motors’ exhaustpipes might be the cause of the problem. Toomuch carbon monoxide in the water can restrictthe flow of oxygen through the blood.

Testing a HypothesisScientists found no evidence that carbonmonoxide had ever caused large fish kills in thearea. Still, they wanted to test their hypothesis.They performed a series of tests in the lab and at the river. They discovered that high levels ofcarbon monoxide were, in fact, killing the fish.The plant was testing more powerful motorsthan it had tested in the past. These motors were injecting more carbon monoxide into thewater than the less powerful motors did in thepast. The new fish kills were the result of thesehigher levels.

After scientists notified the company of theirresults, the company installed an exhaust venti-lation system. This system helped prevent car-bon monoxide from entering the water. No fishkills have been reported since the installation ofthe ventilation system.

Applying Problem Solving Skills1. If scientists had discovered that the outboard motor plant was not polluting the water, what step

would you have recommended that they take next?

2. According to some researchers, one result of the increase in carbon dioxide in the air from theburning of fossil fuels is that the ocean absorbs more of it. Based on the findings in this article,what might be a result of increased carbon dioxide levels in the ocean? Form a hypothesis andsuggest one way in which you would test your hypothesis.

Outboard motors inject carbon monoxide into the water.

2

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

Breaking All the Records

Every two years, the Olympic games give athletesaround the world a chance to compete. The per-formance of Olympic athletes improved dramat-ically in the twentieth century. The distance ofthe men’s long jump increased by 66 percent.The distance of the shot put increased by 100percent. The length of the ski jump increased by 700 percent.

Four-Minute MileAdvances in training techniques, sports science,and sports medicine have led to these improve-ments. One of the improvements that generatedthe most attention was the mile run. Before1950, people thought that no one could runthe mile in less than 4-min. Now, however,

most world-class athletes routinely break the 4 min mile record. In fact, in 1999, Hicham elGuerrouj broke the 3-min, 45-s mark.

Dr. Trevor Kitson of Massey University in New Zealand comparedrecords for the mile run with thedates of those records. He observedthat the graph of this data was astraight line. From the graph, he predicted that the mile might berun in 3 min, 30 s by the year 2033.

By following the line downward tothe x-axis, it looked as though themile would be run in 0 min, 0 s bythe year 2528.

Predicting PerformanceOf course, running a mile in 0 min, 0 s is impos-sible. Still, Kitson’s graph provided an interestinglook at sports improvements over time. Whichimprovements will happen next? When will theyhappen? What limits might someday be reached?

2Activity

ProblemSolving

Applying Problem Solving Skills

1. Use the blank graph above to construct a graph similar to the one constructed by Dr. Kitson. Usethe information in the table. Are the points in a straight line?

2. What probably will happen to the shape of the graph of mile-run records versus years as timegoes on? Draw a sketch of the possible graph on another sheet of paper.

3:40

3:45

3:50

3:55

4:00

Tim

e (m

inut

es)

1958 1964 1970 1976 1982 1988 1994 20001952

1954

1967

1985

1999

Mile runtimeRunnerDate

Sir Roger Bannister

Jim Ryan

Steve Cram

Hicham el Guerroj 3:43.13

3:46.32

3:51.1

3:59.4

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

3

3ActivityPower from FluidsProblem

Solving

What makes a vehicle come to a stop when the driver steps on the brakes? In a car or atruck, the driver is applying pressure to a fluid.Using fluids to operate or move an object iscalled hydraulics.

Pascal’s PrincipleLiquids and gases are classified as fluids. A fluidhas the ability to flow. It is known that a fluidexerts pressure in all directions. Pressure isdefined as the amount of force applied over agiven area.

Blaise Pascal (1623–1662) combined thesetwo concepts into an idea now known as Pas-cal’s principle. It states that pressure applied to aconfined fluid is transmitted unchangedthroughout the fluid. The advantage gained byPascal’s principle is that an input force over asmall area is translated into a large force over alarge area (with equal pressure at both ends).

The hydraulic brake system of a car is anapplication of Pascal’s principle. Hydraulicbrake systems use a pressurized liquid to do thework. When the brake pedal is pressed, themaster cylinder presses on the brake fluid in thebrake lines. This same pressure is transferred tothe brakes. At each wheel, the brake system usesthis pressure to exert a force on brake shoes ordiscs. These cause the car to stop by rubbingagainst the wheels.

Increasing ForceWith hydraulics, it’s easy to increase the amountof force. It’s done by trading force for distance.The input force on a small area moves over along distance, while the large force on a large

area moves through a proportionally smallerdistance. Although a larger force may be gener-ated, the work done is the same.

Liquid versus GasWhy is a liquid used in brake lines instead of agas, such as air? A liquid cannot be compressed.When it is put under pressure, its density doesnot change. A gas, however, is compressible. If agas were used in a brake system, pushing thepedal would just compress the gas. It would notmake the brakes move. That’s why it’s importantto remove or “bleed” air from the brake lineswhen brakes are serviced on a car.

Applying Problem Solving Skills1. Pascal’s principle states that when pressure is exerted on an object, it puts an equal amount of

pressure on another object in that system. What would be one way to increase the amount ofpressure being exerted from one object to another?

2. The brakes on your family car do not work as well as they used to. What might be the problem?

Apply force

4

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

Discovering Hidden Planets

In the first half of the 1800s, astronomersnoticed that there was something wrong withthe orbit of the planet Uranus. It wasn’t follow-ing quite the right orbit for a planet that isaffected just by the gravity of the Sun and thegravity of other planets. The orbit had an unex-pected acceleration that resulted in a little wob-ble. This wobble in Uranus’s orbit led scientiststo hypothesize that another planet must bepulling on Uranus. It wasn’t long beforeUranus’s neighbor, Neptune, was discovered.

Looking for the “Wobble”Like tireless detectives, astronomers continue toimprove on their methods of finding and fol-lowing clues in space. Scientists have identified50 planets outside our solar system and morediscoveries are likely on the way. Astronomersmade these findings with tools that allow themto detect and measure the effects of gravity onobjects in the universe.

One technique scientists use is the Dopplereffect. As an object is pulled by a planet’s gravi-tational field and moves relative to Earth, itslight frequency changes from blue (when theobject is closer to Earth) to red (when it is far-ther from Earth). Scientists placed bottlediodine vapor on the focus of a telescope,removing certain colors from the light spec-trum, and found six planets. This technique

allows scientists to detect slight shifts in thelight frequency of stars as planets move aroundthem. Measuring the shift in the color spec-trum tells scientists about the orbit and mass ofthe planets.

Sometimes, because of the angle of planets, thelength of time of their orbits, or the massiveamounts of dust in young planetary systems,measuring light shifts is impossible. In thosecases, scientists also look at the spiral patternsplanets leave in the dust disks where they form.The patterns tell scientists about the size and orbitof individual planets. This method helped scien-tists locate a planet ten times the mass of Earthorbiting the star Beta Pictoris.

Using Radio TelescopesRadio telescopes also allow scientists to explorespace objects that do not show up with light-sensing techniques. Radio waves can detectobjects in young planetary systems with lots ofdust. This technique helped researchers find ayoung star cluster—less than 1 million yearsold—in the beginning of its formation.

Because of improved technology, the abilityto identify planets has increased dramaticallyover the last five years. Scientists have evenfound a multi-planet system around the starUpsilon Andromedae. NASA plans to launch aspace telescope mission to look for new planets.

4Activity

CriticalThinking

Applying Critical Thinking Skills1. What would happen to the motion of a spacecraft if it traveled near asteroids or comets?

2. When would the orbit of Uranus be most affected by Neptune?

3. A person who weighs 45.4 kg on Earth would weigh only 7.6 kg on the Moon. This difference isrelated to the difference in mass of the Earth and the Moon. Write a general statement thatexpresses the relationship between mass and gravitational force or weight.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

5

5ActivityNew Insulation for

Space ShuttlesProblemSolving

Imagine a vehicle designed to withstand tem-peratures ranging from –156.7°C to 1,648.9°Cand hundreds of voyages out of Earth’s atmos-phere into space and back again. Space shuttles,designed for repeated space missions, are con-tinuously being improved to make them betterinsulated against such extreme temperatures.

Extreme HeatWhen a space vehicle reenters Earth’s atmos-phere after orbiting Earth, it is subjected to hightemperatures caused by air friction. The amountof heat depends on the shape of the vehicle andits position during re-entry. On a space shuttle,the nose and some parts of the wings encounterthe highest temperatures during reentry.

Before shuttles became a part of the spaceprogram, little consideration was given toreusing the materials that shielded space cap-sules from heat. Heat shielding involved usingmaterials that would vaporize upon reentry.

Today’s space shuttles are made of materialsthat can withstand hundreds of trips into space.

A thermal protection system with reusablematerials protects the crew and contents of theshuttle from the heat of reentry, the cold ofspace, and the ice that forms on fuel tanks whenthe vehicle is awaiting launch.

Space-Age InsulatorsA variety of materials are used as insulators. Mostof them contain silica fibers. These materials arenonconductors. They work by preventing heatfrom passing to the shuttle’s surface. In additionto being good insulators, materials must bestrong, lightweight, flexible, and reusable.

NASA has made improvements on older ver-sions of tiles that were used to cover the outsideof spacecraft. Some of them now have a layer ofa substance called aerogel made of silica, alu-mina, carbon, or other materials. The aerogelacts like a vacuum. It does not allow air or anyother gas to transmit heat through the material.

Installing the TilesEach tile is installed over a slightly flexible pad.It is held in place with a silicone rubber adhe-sive. Depending on the amount of protectionneeded, the tiles vary in thickness from about1/2 cm to almost 4 cm. Different types of tilesare used in different areas. Black tiles coverplaces that reach temperatures no higher than1,260°C; white tiles cover areas that reach tem-peratures no higher than 648.9°C.

Some parts once protected with tiles now arecovered with a new material called reinforcedcarbon-carbon. This material covers surfaces,such as the area from the nose cap to the noselanding gear doors, that are exposed to temper-atures greater than 1,260°C. Insulating blankets,which are easier and cheaper to maintain thantiles, replaced tiles on the mid-body section ofthe shuttle Columbia.

Applying Problem Solving Skills1. Why do you think the tiles that cover the outside of the spacecraft must be flexible?

2. Why would the nose encounter more intense heat than other parts of the shuttle during reentry?

United States

USA

1500

°C

1500

°C

Space shuttles are designed to withstand intense heat.

6

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

The Appeal of Perpetual Motion Machines

Machines are supposed to make work easier.Is it possible to build a machine that will runendlessly on its own after it is started, with nooutside energy source? Some creative thinkersin the seventeenth century tried to build such amachine. At that time, building a perpetualmotion machine was a popular topic amongtinkerers and would-be inventors. Thousands ofdesigns were created. Some were actually built.

A Good Idea, but . . .Take, for example, one design for a perpetuallyspinning wheel. It put to use many known simplemachines—wheels, gears, levers, inclined planes,and a giant moving screw called an auger. A largewheel had compartments to hold heavy woodenballs. It resembled a Ferris wheel with a woodenball in each “seat.”

Instead of getting on at the ground level, awooden ball would be dropped into the topcompartment from above. Then the weight ofthe ball would make the wheel turn. When theball got to the bottom of the wheel, it wouldroll out of its seat, down a chute, and into anauger, and it would be powered by gears andlevers attached to the turning wheel. The ballwould then ride to the top of the auger like itwas an elevator. When it was at the top, the ballwould drop onto the wheel again.

Facts of FrictionAs balls kept dropping and rolling, the wheelwould keep spinning over and over forever,right? Wrong. What the inventors didn’t thinkabout was friction. When the wheel spun,balls rolled, or gears turned, surfaces came into contact and friction occurred. Enoughenergy was lost to friction that the wheel could never get started. Despite all their com-plexity, this and other perpetual motionmachines failed to deliver.

Breaking the LawsThe first two laws of thermodynamics, formu-lated in the nineteenth century, explain why themachines cannot work. The first law, the law ofconservation of energy, states that energy can-not be created or destroyed but always convertsit into another form. The machines must losesome energy when they operate; through fric-tion, for example. The second law states thatthe loss of a machine’s energy could be redi-rected back to the machine only by an outsidepower source.

Interest in perpetual motion machinesseemed to wane when the internal combustionengine was invented. Tinkerers turned theirattention toward using engines to make jobs easier.

6Activity

ProblemSolving

Applying Problem Solving Skills1. Sometimes, when calculating the work input and work output of machines, an ideal machine is

used as a model. An ideal machine is not real because it does not create friction and no energy isconverted to heat. It is used because work input equals work output. How does an ideal machinecompare to a perpetual motion machine?

2. What assumption is made about the amount of energy input and output in the perpetual motiondevices? Why was it unrealistic to expect them to work?

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

7

7ActivityStonehenge—

An Engineering MarvelProblemSolving

In southern England on Salisbury Plain standsa group of huge stones. Called megaliths, thestones are part of a structure created by peoplewho lived in prehistoric Europe. The structure,called Stonehenge, is considered to be one ofthe most remarkable achievements of prehis-toric engineering. How could people have pos-sibly moved such heavy stones over such a longdistance and then set them in place?

Where did they come from?Stonehenge is estimated to have been built inphases between 3100 B.C. and 1500 B.C. Itincludes stone and timber structures, andcarved earthen ditches and banks. One type ofstone used in the monument, bluestone, isfound hundreds of kilometers away in the Pre-seli Hills in southwest Wales. The heaviestpieces of stone, called the sarsens, likely camefrom a site 30 km north of Stonehenge. Thestones form a horseshoe surrounded by a circleand originally were topped with smaller stonescalled lintels.

How were they moved?The question of how the stones were movedhas intrigued scientists for years. One theory isthat they were moved by boat, then dragged onsledges and rollers. A sledge is a low platformwith runners. It resembles a sled. To pull theheaviest stones up hills, about 500 peoplewould have been needed to pull the ropes onthe sledges. An extra 100 people would havebeen needed to lay the rollers in front of thesledge. They also would have had to keep thesledge from wandering sideways. Scientists

estimate that it might have taken 1,000 peopleseveral years to move 80 sarsen stones a dis-tance of 30 km. Another theory is that theheavy rocks were already in the area aroundStonehenge, carried there by glaciers.

Using Simple MachinesThe diagrams below show methods andmachines that probably were used to raise thesarsens and the lintels into place. The methodthat was used to raise the lintels has been usedby modern engineers in countries where no gas-powered cranes were available.

Applying Problem Solving Skills1. Suppose a new Stonehenge were to be constructed in the near future. What modern machinery

could be used to raise the sarsens and the lintels? How many workers would be needed for thisnew Stonehenge project? Explain.

2. Do you think the sarsens and the lintels could have been transported over hundreds of kilome-ters of land to construct Stonehenge? Why or why not?

3. Write a step-by-step plan of how someone who lived between 3100 B.C. and 1500 B.C. mighthave organized such a large project.

Raising the sarsens

Raising the lintels

8

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

Energy-Saving Refrigerators

Until the 1980s, refrigerators used a great dealof energy and were cooled with substancescalled chlorofluorocarbons (CFCs). However,scientists discovered that CFCs can destroy theozone layer in the atmosphere, which blocksthe Sun’s ultraviolet rays.

For this reason, in 1987 most of the indus-trial nations of the world signed a treaty, agree-ing to reduce CFCs 50 percent by 1998 and toeliminate them by 2000. Today’s refrigeratorsuse CFC-free methods of cooling, making themmore energy efficient.

Energy HogsRefrigerators still use more electricity than anyother kitchen appliance. However, modern refrig-erators use less than half the energy of a refrigera-tor built in the 1970s. In fact, they are so efficientthat the Department of Energy states that if everyhome upgraded to a new refrigerator, the UnitedStates would save 3.8 billion L of oil per month.That reduction in fuel use would eliminate theneed for more than 20 power plants.

Today’s refrigerators stay cool with a mecha-nism that draws out heat through the evapora-tion of a liquid. Liquids absorb heat as they cool.Refrigerator liquids, called refrigerants, have alow boiling point. The boiling point is so low thatthe boiling liquid would feel extremely cold tohuman touch. The liquid, therefore, evaporates ata low temperature. It draws heat out with it,keeping the inside of the refrigerator cold.

Cool ItA refrigerator should be placed in a position toallow proper ventilation behind and above it soheat can escape efficiently. It should not be

placed next to other heat-producing appliances,and the door seals should be airtight. The tem-perature should remain between 2.8°C and4.4°C in the main compartment and -17.8°C to -15°C in the freezer. Extra features, such as auto-matic icemakers and water and ice dispensers inthe doors, reduce efficiency.

Consumer InformationThe federal government now requires thatEnergyGuide labels (like the one below) appearon all new appliances, listing how much elec-tricity an appliance uses in one year. The higherthe number of kilowatt-hours (kWh) it lists,the more energy it uses and the more expensiveit is to operate.

8Activity

ProblemSolving

Applying Problem Solving Skills1. Think of another appliance that people might have in their homes that could be more energy

efficient. Describe two methods you might use to test your assumption.

2. Use the information in the EnergyGuide above to calculate how much it would cost to operatethis refrigerator for one year. Base your calculation on a 2000 U.S. government report that saysthe average cost of a kilowatt-hour of electricity is 8.034 cents. Round your answer up to thenearest dollar.

Refrigerator–FreezerWith Automatic DefrostWith Side–Mounted FreezerWith Through–the–Door–Ice Service

XYZ CorporationModel ABC–W

Capacity: 23 Cubic Feet

Compare the Energy Use of this Refrigeratorwith Others Before You Buy

Energy use (kWh/year) range of all similar modelsUses Least Energy685

Uses MostEnergy

1000

This Model Uses900 kWh/year

Based on Standard U.S. Government tests

kWh/year (kilowatt–hours per year) is a measure of energy (electricity) use.Your utility company uses it to compute your bill. Only models with 22.5 and 24.4cubic feet and the above features are used in this scale.

Refrigerators using more energy cost more to operate.This model’s estimated yearly operating cost is:

$

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

9

9ActivityRadon RiskProblem

Solving

Radon-222 is an element found almost every-where. It is produced from the decay of two nat-urally occurring elements, radium-226 anduranium-238, found in rock and soil. As a gas,radon is mobile. It poses little risk if it makes itsway into open air. But if it seeps into a house, itcan collect in hazardous concentrations.

Dangerous By-ProductsRadon decays into another element, polonium-218, and releases an alpha particle. Polonium-218further decays into lead-214, to bismuth-214, andto polonium-214. These by-product elements,called radon daughters, can be inhaled directly,or they can attach to dust particles that lodge inthe lungs. After they are in the lungs, radondaughters can emit alpha particles that can causelung cancer. In fact, radon is second only tosmoking as a cause of lung cancer.

The location of a house can, to some extent,reveal whether radon might be a problem. Forexample, certain types of rocks—light-coloredvolcanic rocks, granites, dark shales, sedimen-tary rocks containing phosphate, and metamor-phic rocks formed from these rocks—have highuranium contents. Houses that rely directly ongroundwater also are at higher risk for radonbuildup. The only way to find out whetherradon gas is in your house is to test for it.

Test kits are available in stores. If the radonlevel in your house is high, contact your localhealth department or the EPA for further infor-mation on testing for radon.

Reducing the RiskMethods that might help decrease radoninclude the following: (1) provide natural ven-tilation to the basement; (2) supply wood-stoves, furnaces, and fireplaces with an outsideair supply; and (3) close entry points. Recallalso that radon is a gas. It can travel morequickly through porous, dry soils than it canthrough damp, clayey soils.

Applying Problem Solving Skills1. Why might houses that rely on groundwater be at risk for radon buildup?

2. Why is ventilating the basement a good way to reduce radon buildup?

3. Based on radon movement, what type of setting could be the safest for building a house?

Common Radiation Sources

Sun

Syntheticsources

Other naturalsources

Radon

55%

18%27%

Rn

10

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

What’s the difference?

If you begin paying attention to all the physicaland chemical changes going on around you, youwill have countless opportunities to become anexpert at telling the difference between them.

Dawn to DuskIn the morning, the cold water you place on thestove begins to boil for hot cereal. You noticethe condensation of steam vapor on the bath-room mirror. After breakfast you put on yourwarm, leather jacket and thick-soled boots,because last night’s rain turned from water toice on the sidewalk.

You take a bus to meet a friend. Inside thebus engine, gasoline is being burned in thepresence of oxygen with a release of energy thatmoves the bus. The burning fuel also producessome exhaust in the form of carbon monoxide

and other pollutants. You get off the bus near abig statue in your town’s main square. Thestatue has turned green with a patina ofhydrated copper carbonate.

You and your friend meet and walk to thelibrary. Your breath comes out as steam in thechilly air. All that aerobic exercise has caused thebuildup of lactic acid in your muscles, makingyou feel tired. So you get your favorite carbon-ated beverage to drink and watch as bubblescome up out of the solution. You board the busfor home, rubbing your hands together rapidlyto keep them warm.

Seeing Is BelievingLooking back on your day, you smile as you real-ize how many chemical and physical changes younoticed—and how well you understood them.

10Activity

CriticalThinking

Applying Critical Thinking Skills1. Write which are physical changes and which are chemical changes. Give a reason for each answer.

cold water heating up to its boiling point:

rain turning to ice:

thick-soled boots preventing slipping on the ice:

gasoline and oxygen combining to release energy and waste products, including carbon monoxide:

copper metal combining with gases in the air to form a patina of hydrated copper carbonate:

breath coming out as steam:

sugars and oxygen in the muscles producing lactic acid:

carbon dioxide gas escaping from a solution in the form of bubbles:

rubbing hands rapidly together to warm up:

2. Methods for cleaning clothing have not always been as efficient as they are today. Fabric wassometimes soaked in buttermilk and left in the Sun. The lactic acid in the buttermilk combinedwith the sunlight caused fabric to bleach white. Do you think that was a physical or a chemicalchange? Suppose you want to bleach a stain out of your favorite white sweatshirt today. Wouldthis require a physical or chemical change? Why?

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

11

11ActivityAncient Mysteries and

Carbon-14 DatingCriticalThinking

When did the last of the mammoths live? Howold are the Dead Sea Scrolls? Physicists are ableto determine the ages of ancient artifacts bymeasuring the residues of atomic behavior.

In 1946, Willard F. Libby of the University ofChicago developed a method that determinesthe age of carbon-containing materials. Thecarbon atoms in the materials can be used todetermine the materials’ age, back to about50,000 years. Libby’s method, called radio-carbon dating, earned him the Nobel Prize inChemistry in 1960.

How does it work?Radiocarbon dating, or carbon-14 dating, usesthe fact that all living matter contains carbon.Three isotopes of carbon are found in livingmatter. Carbon-12 and carbon-13 are stable iso-topes and have been around for a long time.The other isotope, carbon-14, emits beta (elec-tron) radiation as it changes to carbon-12 orcarbon-13. The rate at which carbon-14 changesis called the decay rate. If the amount of car-bon-14 in a piece of material can be found, andthe decay rate for carbon-14 can be measured,the age of the material can be determined. The

decay rate for carbon-14 has been established.Half of the existing carbon-14 atoms will decayin 5,730 years and half of the rest of the carbon-14 atoms will decay in an additional 5,730 years.

Dating the Dead Sea ScrollsResearchers used radiocarbon dating to deter-mine the age of the Dead Sea Scrolls. A herds-man looking for a stray goat in caves east ofJerusalem found the first of the scrolls in 1947.The scrolls almost instantly sparked scholarlycontroversy. Nearly 50 years later, however, thedate of the scrolls was settled by radiocarbontesting.

In 1994, researchers from the University ofArizona dated 18 of the texts. The paper fromone of the texts dates to between 150 B.C. and 5 B.C. with a 95 percent probability. The datesthe Arizona team found confirmed dates foundby a lab in Zurich, Switzerland, in 1990. TheArizona team took small samples from theragged edges of the manuscripts and analyzedthem using a tandem accelerator mass spec-trometer. Using small samples of material, theaccelerator measures the amount of carbon-14in a substance.

Applying Critical Thinking Skills1. What do scientists assume to be true when carbon-14 is used to date artifacts? Can you think of

reasons why those assumptions might not be true?

2. Why can’t carbon-14 dating be used to determine the age of dinosaur bones?

Examples of How Carbon Dating Has Been UsedTutankhamen

An examination of mummified remains revealed that thisEgyptian child-king reigned more than 3,300 years ago.

StonehengeCarbon dating of wood in the area revealed that this circle of huge stones was built by a group of prehistoric people who lived inEngland 5,000 years ago.

3100 B.C.

1323 B.C.

12

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

Pollution Goes Underground

According to the Environmental ProtectionAgency (EPA), half of all the people in theUnited States rely on groundwater for the waterin their homes. Groundwater also is pumped tothe surface for use by industry and in irrigatingfarmland.

The Hydrologic CycleGroundwater is part of the hydrologic cycle,which involves the continuous movement ofwater from Earth to the atmosphere and backagain, through evaporation and precipitation. Itcollects naturally in the ground when rain orsnow soaks into the soil. It moves through thesoil between rocks, until it reaches rocks thatare impermeable to water. The area just abovethis is filled with rock fragments. Water collectsin the small spaces between these fragments,called pores.

Large areas where water flows freely throughpermeable rock are called aquifers. The top levelof such an area of water is called the water table.

Underground PollutionUntil about 30 years ago, many people believedgroundwater was immune to pollution becauseof the many layers of soil surrounding it. Theyalso thought that sand, gravel, and clay effec-tively filtered out pollutants. In spite of all thisnatural filtration, the EPA reports that everystate has some contaminated groundwater.

Contamination can start at the surface, in theground above, or below the water table. Thecloser a pollutant is introduced to the ground-water, the more powerful its effect is. Pollutantsintroduced farther away have less effect becauseof the natural processes of filtration, dilution,oxidation, and biological decay.

One category of groundwater pollutants isvolatile organic compounds, often called VOCs.These are organic chemical compounds thatevaporate easily. They contain hydrogen, car-bon, and sometimes other elements. Thesechemicals are found in fuel, paint, paint thin-ner, dry-cleaning chemicals, and other prod-ucts. They can leak into groundwater as liquidsfrom landfills, leaky storage tanks, spills, andstorm water runoff from paved areas. Whenthey become airborne, these chemicals cancombine with rain, fall back to Earth, and soakinto groundwater as part of the natural hydro-logic cycle.

Watching Waste Many groundwater pollutants come from theimproper disposal of household waste. Motoroil, pesticides, cleaning products, weed killers,paint cans, batteries, and other toxic wasteitems should be set aside for hazardous wastepickup. Keeping them out of drains, landfills,and yards helps protect groundwater.

12Activity

CriticalThinking

Applying Critical Thinking Skills1. Why do you think it took people so long to realize that groundwater can be polluted?

2. If you were on a committee that was asked to find a location for a new landfill in your county,what advice would you give to the committee?

Sources of groundwater pollution

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

13

13ActivityThe Birth of an ElementProblem

Solving

What happens when you take two small piecesof clay and smash them together? The singlepiece that results is as big as the two smallerpieces. That’s similar to what scientists did tocreate a new element.

In 1994, after ten years of work, a group ofresearchers collided nickel with lead. The two ele-ments fused and a new, much heavier syntheticelement, number 110, was created. Although ele-ment 110 only lasted 0.001 s, its discovery helpedto provide a better understanding of superheavyelements and how they can be created.

Adding to the Periodic TableBetween 1994 and 1999, Russian, German, andAmerican scientists created many other newelements. They discovered elements 111, 112,114, 116, and 118.

These elements were created using a devicecalled a particle accelerator. It acceleratesatomic particles to a high speed. When particlestraveling close to the speed of light collide, theyform a new element.

Because these elements break down withinsuch a short period of time, scientists have notbeen able to study their properties. Element 114lasted between 20 s and 30 s. That’s much longerthan the life span of elements 109 through 112, soit was the first considered to be somewhat stable.

Gone in the Blink of an EyeElement 116 was in existence for only .0012 s,and element 118 was around for only .0002 s.Element 118 was created when scientists bom-barded lead with a million trillion ions of kryp-ton for more than ten days. Three atoms ofelement 118 came out of this experiment. Theatoms quickly broke down into elements 116,114, and other elements.

Because of this experiment, scientists thinkthey can make element 119 by colliding bis-muth and krypton. They believe element 119would break down into elements 117, 115, and113, which are yet to be discovered.

Applying Problem Solving Skills1. Use the periodic chart to explain how colliding lead and nickel atoms could create an element

assigned the atomic number of 110.

2. Name two solid, metal elements that scientists might use to create an element with an atomicnumber of 129.

Particle

Electromagnets

Accelerating section

Fixed target

Particle accelerator

14

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

Gasoline—Findinga New Formula

The carbon monoxide and other chemicals thatspew from the tailpipes of the many millions ofcars and trucks in the United States create thesmog that blankets our country’s largest cities.Laws have been passed requiring manufacturersto make vehicles that operate more efficiently.In 1995, however, a federal program waslaunched requiring oil companies to makechanges in gasoline.

The cities with the most smog were the tar-gets of the program. The new gasoline, calledreformulated gasoline or RFG, had to burnmore cleanly and release fewer smog-formingand toxic pollutants.

Finding the FormulaThe federal government required oil companiesto create their own formulas to meet the stricterstandards. One requirement was that the gasolinecontain two percent oxygen.

To oxygenate the gasoline, most oil companieschose to add either ethanol or a chemical calledmethyl tertiary-butyl ether (MTBE) to their for-mulas. Both reduce the amount of carbon monox-ide that is released when gasoline is burned.

But despite benefits, drawbacks to using each ofthese chemicals exist. MTBE is highly soluble and

travels easily in water. Spills, improper disposal,and leaky tanks can pollute ground-water and sur-face water. Ethanol is an alcohol produced by thefermentation of sugar. When it is added to gaso-line, it reduces the amount of carbon monoxidethat is released and creates more oxygen thanother additives create. However, it causes gasolineto evaporate more quickly. As gasoline evaporates,it releases more pollutants into the air.

Despite the quick evaporation, however, theEnvironmental Protection Agency (EPA) claimsthat using ethanol as an additive is much betterfor the environment than using MTBE. TheEPA recommends that the use of MTBE ingasoline be reduced or eliminated.

Noticeable ImprovementAlthough questions remain, the RFG programhas been successful in reducing pollution in thetargeted areas. According to the EPA, at least 75million people breathe cleaner air today thanthey did before RFG. At least 17 states and theDistrict of Columbia use reformulated gasoline,and at least one-third of the gasoline sold in theUnited States is reformulated.

14Activity

CriticalThinking

Applying Critical Thinking Skills1. What factors do you think the EPA had to consider before recommending the use of ethanol over

the use of MTBE in reformulated gasoline?

2. What opinions might auto manufacturers have about the RFG program? Ethanol producers?Oil companies?

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

15

15ActivityBuilding Materials

of the FutureProblemSolving

What do soft-drink bottles, plastic bags, andcompact discs have in common? They’re allpolymers. The word polymer comes from thegreek word polumeres, which means “havingmany parts.” A polymer is a chemical compoundmade up of large molecules formed from manysmaller molecules. These molecules are linkedtogether in long chains.

A Closer LookThe arrangement of the chains determines theproperties of the polymer. Rubber is a polymerthat is made up of long, kinked chains. Whenrubber is pulled, it snaps back, demonstrating itselastic quality. Polymers with chains of moleculesheld tightly together, such as Formica or Plexiglas,are stronger but less flexible.

Rubber, cellulose, and wool are natural poly-mers. Nylon, plastic foam, nonstick coating,and hundreds of other types of plastics areexamples of synthetic polymers.

Aluminum AlternativePolymers are twice as light as aluminum and canbe molded into many more shapes. This makesthem an interesting alternative to aluminum.Some race car bodies are made from a complexform of polymer, known as a polymeric compos-ite. Polymeric composites are plastics that havebeen reinforced with glass or carbon fibers. Com-posites, however, are very expensive.

Plastics Plus FiberEngineers are experimenting with the use offiber-reinforced plastics in structures such asbridges. Smith Road Bridge in Butler County,Ohio, is the nation’s first bridge made completely

from plastic reinforced with carbon fibers. Afour-member team from the Wright-PattersonAir Force Base near Dayton created the space-agematerial that was used to build the bridge. Calleda “smart bridge,” it can hold up under extremetemperature changes and can support a load ofmore than 36,000 kg. The Smith Road Bridge isfive times stronger than one made just like it outof concrete and steel.

In addition to being strong, smart bridges lastthree times as long as other bridges. Concreteand steel bridges last only about 50 years andoften need repair. Smart bridges need little or norepair, making them cheaper to maintain. Even-tually, smart-bridge technology could replace orhelp repair almost 230,000 bridges—nearly halfthe nation’s concrete and steel bridges.

Applying Problem Solving Skills1. Look at the three illustrations of polymers. Judging from the appearance of each type of chain,

which type of polymer would be strongest?

2. Besides bridges and automobiles, suggest two other ways that reinforced plastics might be used toreplace materials that are now being used in other products and structures. What advantagemight the use of plastics provide?

Linear

Branched

Network

Polymer structures

16

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

Acid Precipitation Report Card

We might think of acid rain asa modern-day environmentalproblem, but it’s not. In 1872,the effect of acid precipitationwas discovered in Britain—the world’s first industrializednation. A Scottish scientist sawa link between the sulfur diox-ide that was being releasedwhen coal was burned and thedamage being done to localplant life. He studied thechemistry of rain, fog, andsnow. He found that high lev-els of sulfur gas were mixingwith moisture in the air tocreate highly acidic precipita-tion. He called it acid rain.

Identifying the ProblemIt wasn’t until the 1950s, however, that acid pre-cipitation became a public concern. In December1952, 4,000 Londoners died as a direct result of akind of air pollution known as smog. After that,British politicians passed the world’s first air pol-lution law, the British Clean Air Act. Industrializednations, however, continued to build smokestacksat their factories, so acid pollution got worse.

Worldwide research throughout the 1960sand 1970s showed a strong link between acidprecipitation and contamination of soil, forests,and lakes. The highly acidic conditions werekilling plants, trees, and fish. Canada com-plained that acid rain caused by car emissionsin the United States was killing fish in Canada.By 1980, a joint report from the United Statesand Canada showed that air pollution was,in fact, crossing the border between these two countries.

By the early 1990s, Austria and Sweden hadreduced their sulfur dioxide emissions by anaverage of 81 percent. Thirteen other Europeancountries cut their emissions in half; nine moreand Canada each cut their emissions by morethan one-third. By 1992, the United Statesshowed a decrease of only 13 percent.

Weighing the CostsEven though acid pollution continues to be aproblem, the public’s attention has moved toother problems, such as global warming anddepletion of the ozone layer. The 1990 CleanAir Act Amendments in the United States stillrequire strict controls, but the cost of control-ling emissions is expensive. Controlling sulfurdioxide emissions costs $1 billion to $5 billionper year and controlling nitrogen oxide costs$75 million to $90 million each year. However,many people think the damage to forests, lakes,buildings, plants, animals, and humans is evenmore costly.

16Activity

ProblemSolving

Applying Problem Solving Skills1. How do you think the Scottish scientist in 1872 linked the condition of the plants to acid precipi-

tation? Describe two things he would have to do to make this connection.

2. Based on the map, which part of the United States has acid precipitation with the highest pH lev-els? Why do you think this is the case?

greater than 4.84.7-4.84.6-4.74.5-4.64.4-4.54.3-4.4less than 4.3

Acid Precipitation pH Levels 1999

pH level

(pH level of normalrain is about 5)

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

17

17ActivityEnvironmentally Friendly CarsCritical

Thinking

How would you like to own a car that is noise-less, does not pollute, never needs a tune-up,and rarely needs major repairs? An electric carmight be the answer.

Plug It InAuto manufacturers have been experimentingwith the idea of replacing gasoline engines withelectric motors for many years. One car manu-facturer in the United States recently startedselling the first mass-produced electric car.Recent improvements allow the car to gobetween 89 and 153 km or 120 and 209 kmbefore recharging, depending on the type ofbattery pack.

Widespread use of electric cars would elimi-nate the pollutants emitted from gasolineengines. Electric cars do not use energy whenthey are not moving. With an electric car, driverscould save money on gasoline, tune-ups, andmajor repairs.

Electric cars do have disadvantages, however.They are more expensive to buy than similargasoline-engine cars. They can travel only shortdistances before they need to be recharged, andbatteries must be replaced two or three timesduring the life of the car.

The standard lead-acid batteries used in electriccars are heavy, expensive, and take up a lot ofspace. They are also hazardous to the environmentwhen they are discarded. Electric cars accelerateslowly and reach a top speed of only about 129 kmper hour. Although electric car engines burn morecleanly, they still cause some pollution.

A Dual ApproachIn response to the problems of electric cars, Japan-ese automakers began selling hybrid models thatuse electricity and gasoline. These cars rechargethemselves by storing energy produced duringdeceleration and then convert it back into electricpower. They accelerate more quickly and theiraerodynamic shape minimizes wind resistance,allowing for better gas mileage. A computer deter-mines when it is most efficient for the car to useelectricity or gasoline.

Other automakers have plans to release carsthat use electric-diesel engines and fuel-cell-powered engines. Fuel cells are now used inspacecraft. The cells take hydrogen from thefuel and mix it with oxygen. The reaction, inturn, generates electricity. Fuel cells are morethan twice as efficient as gasoline engines. Theironly emission is water vapor.

Applying Critical Thinking Skills1. If you were buying a new car, would you buy an electric car? Why or why not?2. In what ways could governments (federal, state, and local) support the use of electric and

hybrid cars?

18

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

Pole Reversal

You’re lost in the wilderness. Luckily, you havean iron needle, a cork, a small permanent mag-net, and a cup. You rub the needle over themagnet several times in the same direction tomagnetize it. You stick the needle through thetop of the cork and float it in a cup filled withwater. After the cork stops bobbing around, itbecomes still. Then the needle is aligned in anorth-south direction. Knowing where north is,you can head for home. You’ve created a crudecompass, not unlike those that were first usedthousands of years ago by Chinese navigators.

Earth as a MagnetEarly explorers used compasses, but they werestill in the dark about why compasses worked.It wasn’t until a few centuries later that investi-gators discovered that in northern Canada, ahuge area of magnetic iron ore was attractingcompass needles. These rocks were namedlodestone, or leading stone.

When these rocks were formed millions ofyears ago, atoms of iron within the molten rocklined up with Earth’s own magnetic field. Afterthe rocks hardened, the pattern of magneticdomains remained unchanged. Because of thephenomenon, geologists can tell that the mag-netic north and south poles (different from thegeographic poles) have periodically flip-floppedover the course of millions of years.

A Distorted Magnetic FieldDeep within Earth is a core of metal made ofiron and nickel. If you were in outer space andcould sprinkle iron filings around Earth, wouldyou get the characteristic pattern of a magnetic

field? Yes—and no. Earth’s magnetic field doesmagnetize particles in the atmosphere. But thesolar wind caused by the Sun blows on the mag-netic field and distorts it. Instead of a symmetri-cal pattern coming from Earth’s north and southpoles, the magnetic field facing the Sun is roundand the far side has a long, cometlike tail.

18Activity

ProblemSolving

Applying Problem Solving Skills1. Many biologists are puzzled by the ability of birds and other animals to migrate great distances

around the globe with unbelievable precision. Recent studies show that Monarch butterflies may usemagnetic fields for orientation. Some studies reveal that migrating animals have some sort of mag-netic-sensing device in their brains. What element might these sensing devices contain? Explain.

2. Suppose a dogsled race was taking place near the arctic circle. Could the drivers simply read anordinary compass to tell their direction? Why or why not?

1994

N

U.S.

Canada

1984

1973

1962

1948

19041831

The location of the north magnetic pole is really an average position.The pole shifts daily and over the years has moved gradually north.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

19

19ActivityPatient-Friendly

Cancer TreatmentCriticalThinking

Radiation is a word that makes many people thinkof a bad accident at a nuclear power plant. Butradiation in the form of radioisotopes is being usedevery day to treat cancer.

A radioisotope is a single atom of an unstableelement. It is a radioactive form of an elementthat is made by hitting a stable element withneutrons. This usually happens in the core of anuclear reactor or with the help of an accelera-tor. The use of radioisotopes in diagnosing andtreating disease is called nuclear medicine. Inthe United States, almost one out of every threepeople going into a hospital is given a test ortreatment that uses radioisotopes.

Pinpointing the Cancer CellsDoctors are using nuclear medicine to developpromising treatments for cancer patients. Usingradioisotopes, doctors can treat only the badcancer cells. This is not only better for thepatient, but also for destroying the cancer.

With traditional cancer treatments, patientsare given drugs (known as chemotherapy) ortheir bodies are exposed to radiation. Thesetreatments work by killing the cells. The prob-lem is that they kill cancer cells and healthycells. With nuclear medicine, doctors can targetclumps of cancerous cells or tumors.

One promising form of nuclear therapyinvolves joining an antibody with a radioisotope.

An antibody is a protein molecule that bindswith a specific type of cell; in this case, cancercells. When they are put together, the antibodyand radioisotope form a cancer-fighting weaponthat targets cancer cells. The antibody binds itselfto the cancer cell and the radioisotope eventuallybreaks down. When it does, it releases radioac-tive energy, hopefully destroying the cancer.

Doctors are referring to these treatments asbeing patient-friendly because they’re easier onthe patient compared to whole-body radiationand chemotherapy. Whole-body radiation andmany other treatments don’t do much to stop acancer patient’s pain. However, studies on 150patients who received radioisotopes showedthat the treatment reduced up to 80 percent oftheir pain.

A Medical ShortageThere are problems, however, with nuclear thera-pies. Many of the radioisotopes that are used totreat cancers need to be created in a lab with spe-cial equipment. Ninety percent of medical iso-topes used in the United States come fromCanada and other countries. The U.S. Congressprovides millions of dollars each year to theDepartment of Energy to fund production. Thedemand, however, continues to exceed the supply.

Applying Critical Thinking Skills1. Some antibodies that are linked to radioisotopes can take 48 h to find their target cell. What

problem might this cause for a cancer patient?

2. How might other diseases be treated using radioisotopes? Be specific.

20

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

Regulating Nuclear Power Plants

What is a clean, affordable way to supply com-munities with electricity? Some people believethat nuclear power plants are the answer.Countries such as Japan, France, and GreatBritain use nuclear power to supply a signifi-cant amount of their electricity. As of 2000,however, only 24 percent of power in theUnited States was generated by nuclear plants.

Safety ConcernsWhy doesn’t the United States rely more heavilyon nuclear power plants for its energy? Theanswer is safety. In 1979, when a nuclear acci-dent occurred at the Three Mile Island nuclearpower plant in Pennsylvania, people began tofear what could happen if that accident had beenmore serious. The greatest risk is exposure toradiation. The degree of risk depends on theamount of radiation that leaks, whether precipi-tation such as snow or rain occurs simultane-ously (which could carry the radiation directlyinto the ground), wind speeds, and location ofthe accident.

Finding a Dump SiteDisposal of nuclear waste also is a problem,because it remains dangerously radioactive forseveral hundred years. Therefore, it has to bestored in a place where leakage cannot occur.Most of it is buried deep underground in tun-nels of solid rock. Although the threat of conta-mination is low, many people prefer not to livein or near an area where nuclear waste is stored.

Another reason few nuclear power plants arebuilt is money. It costs an extraordinaryamount of money to get licenses and to con-struct nuclear power plants. Because plants canoperate only for a few decades, money also has

to be set aside to dismantle the plant when it isclosed down, or decommissioned. Currently,plants that produce energy-using fossil fuels arecheaper to build and operate.

A Nuclear FirstIn March 2000, the United States governmentrenewed the license of a nuclear power plant forthe first time. The Calvert Cliffs plant obtainedapproval to operate until 2036. The plant islocated in Calvert County, Maryland, 64 kmsoutheast of Washington, D.C.

The Nuclear Regulatory Commission (NRC)took two years to make its decision. It evaluatedthe environmental effects, consulted with fed-eral, state, and local agencies, and reviewed pub-lic input. By the year 2020 it is likely that nuclearplants will provide less than half the power theyprovide in the United States today.

20Activity

CriticalThinking

Applying Critical Thinking Skills1. Should the United States continue to develop nuclear energy as a way to generate electricity? Why

or why not?

2. Suppose your electric company wanted to switch from a coal-burning to a nuclear-powered facility. Would you support the change? Why or why not?

Coal 56%

Nuclear 24%

Naturalgas 9%Hydroelectricity 9%

Oil 2%

Geothermaland other 0.1%

Sources of Power in the U.S.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

21

21ActivitySupersonic ImpactCritical

Thinking

For years, many people thought nothing couldtravel through the air at the speed of sound,approximately 1,207 km per hour. Many early,high-speed military planes experienced shockwaves, and crashed after reaching the speed of sound.

Breaking the Sound BarrierBecause of the difficulty of traveling faster thansound, the speed of sound became known as thesound barrier. But on October 14, 1947, U. S. AirForce Captain Charles E. Yeager flew a Bell X-1rocket plane faster than the speed of sound. Healso experienced shock waves, which were heardon the ground as a sonic boom.

When an airplane travels through the air, itcreates pressure disturbances that travel awayfrom the plane. If the plane travels more slowlythan the speed of sound, the pressure distur-bances move away from the plane faster than theplane itself is moving. When this happens, youhear the sound of the plane before it flies by.

When an airplane travels at the speed ofsound, pressure disturbances pile up in front ofthe plane. This piling up of compressed air iscalled a shock wave. The shock wave increases thedrag on the plane and destroys its lift or upwardforce, making the plane difficult to control.

When an airplane travels faster than thespeed of sound, it gradually moves faster thanthe pressure waves. As the shock wave at thefront of the plane spreads out and reaches theground 2 s to 1 min after flyover, it creates asonic boom that can be heard and felt.

Beyond AirplanesA space shuttle creates a double sonic boomwhen it reenters Earth’s atmosphere. Shockwaves move out and back from its nose andtail. The space between the nose and tail is so

long, the shock waves reach the ground at dif-ferent times, creating a double sonic boom.

In Los Alamos, New Mexico, researchers usemicrophones to listen for sonic booms caused bymeteors entering Earth’s atmosphere. By recordingthe time the sound waves from a meteor start andby checking the frequency at different posts,researchers can tell where the meteor will hit.

Applying Critical Thinking Skills1. Aircraft that travel at supersonic speeds cannot be heard on the ground. Why?

2. What is one advantage to tracking meteors sonically?

Pressuredisturbances

Shockwave

Shockwave

Drag Lift

GroundSlow-flying aircraft

Aircraft flying at the speed of sound

Aircraft flying faster than sound

Ground

Ground

Stages of a sonic boom

22

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

Treating Cancer with Light

One of the most commonly used treatments forcancer is chemotherapy. In chemotherapy,drugs are used to kill cancer cells. One draw-back to chemotherapy, however, is that thepatient usually gets sick. Nausea and other sideeffects occur because the drugs attack healthycells as well as cancer cells.

Targeting the Cancer CellsMedical researchers have found a way to treatsome types of cancers without these sideeffects. The process, called photodynamic ther-apy (PDT), uses lasers and special drugs thatchange in the presence of light.

The treatment begins when patients are injectedwith a photosensitive drug. This type of drug issensitive to a particular kind of light. At first, allthe body’s cells, cancerous and normal, absorb thedrug. After a period of time, most of the normalcells release the drug, but the cancer cells retain it.

Then, a laser is aimed at the cancerous tissue.The photosensitive drug in the cancer cellsabsorbs the light and produces a type of oxygenthat destroys the cells.

Only light of a specific wavelength and energycan transform the harmless photosensitive drug

into a cancer killer. The laser that is used is a low-power red light that is directed through a verythin glass fiber. The laser can be focused preciselyon a single area of tissue. It does not produceheat, so it does not burn surrounding tissue.

However, the laser can penetrate only about 3cm of tissue. For this reason, it only can be usedto treat cancer near the surface of the skin or onthe lining of internal organs.

Reduced Side EffectsOne side effect of PDT is that patients are moresensitive to light for about 60 days after thetreatment. They must wear sunglasses and pro-tective clothing before going outdoors.

PDT currently is being used to treat sometypes of lung and esophageal cancers. It can berepeated several times and also can be usedwith other treatments such as chemotherapyand radiation therapy.

Research continues on other types of lasersand photosensitive chemicals. Doctors hope to find a process that will let them treat can-cers farther below the surface of the skin andinside organs.

22Activity

ProblemSolving

Applying Problem Solving Skills1. Some cancers form thick, round tumors while others are long and flat. Predict which kind of

tumor would most likely respond to photodynamic therapy.

2. The original idea for PDT came from a plant. Compare a plant’s use of light energy to that in PDT.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Name Date Class

23

23ActivitySwimming with SharksProblem

Solving

To an amateur swimmer, 0.1 s might not seemlike much time, but Olympic swimmers knowthat it can mean the difference between a goldmedal and no medal. Many of the swimmerswho won medals at the 2000 Olympics in Aus-tralia say they were able to shave off tenths ofseconds by wearing a new type of swimsuit.

Imitating NatureThe new suits were full-body suits. They hadlong sleeves and pant legs that extended to theankles. The real secret behind the new suits wastheir texture. They were made of a fabricdesigned to mimic sharkskin.

A fish curator at the British Museum of Nat-ural Science is credited with the idea. Henoticed that sharks can glide easily throughwater even though their shape is not particu-larly well-suited to speed.

Under the MicroscopeSharkskin, although it looks smooth, is quiterough to the touch. When magnified, it lookslike thousands of tiny paddle-shaped teeth. Theteeth are the key to its efficiency in water.

According to the suit’s manufacturer, watercannot adhere to its surface. This reduces someof the drag. The more drag that occurs, themore energy the swimmer has to exert. Overthe years, swimmers have donned tighter andsmoother swimsuits, and swimcaps, and evenshaved their bodies to cut down on drag.

Sharkskin suits also help control the turbu-lence churned up by other swimmers. Whenwater is crashing into them from all sides,swimmers must expend added energy to stayon course. The ridges of the sharkskin suitshelp deflect some of that force.

The $600 sharkskin suits take at least 20 min toput on and are skin-tight. However, most Olympicswimmers who wore the suit said it was a smallprice to pay for improving their overall times.

Applying Problem Solving Skills1. Sharkskin suits were valuable to Olympic swimmers because they reduced drag in the water.

What other applications might items made of sharkskin have?

2. Think of a sport that you enjoy participating in or watching. Describe a new piece of equipmentor an article of clothing that might improve an athlete’s performance in that sport.

Full-body swimsuits mimic sharkskin

Magnification of sharkskin

24

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Activity 1 ______________________ page 1Testing the Waters

1. Generating and Assessing Solutions: Answerswill vary. Students should examine probablecauses for fish kills and make a suggestion forfurther reasearch into one of these areas.

2. Making a Hypothesis: Students’ hypotheseswill likely state that carbon dioxide has someeffect on marine life. Students should proposeone way of testing their hypotheses. After com-pleting this activity, you might want to tell stu-dents that studies have shown that increasedlevels of carbon dioxide in the world’s oceanswill increase its acidity. Among other effects,increased acidity can be corrosive to calciumcarbonate, which is a part of shells and coral.

Activity 2 ______________________ page 2Breaking All the Records

1. Examining and Evaluating Assumptions: Ifthe graph is carefully constructed, these pointswill not fall on a straight line. The downwardslope decreases very gradually.

2. Making Predictions: The slope of the curvewill probably decrease and become almost par-allel to the x-axis.

Activity 3 ______________________ page 3Power from Fluids

1. Recognizing Cause and Effect: Students shoulddeduce that if the second object had a largerarea or mass than the first, the force on the sec-ond object would be greater.

2. Generating and Assessing Solutions: Answerswill vary but could include the following: Themaster cylinder is low in brake fluid; there isair in the brake lines.

Activity 4 ______________________ page 4Discovering Hidden Planets

1. Recognizing Cause and Effect: The path of thespacecraft may be changed due to the pull of thegravity of the asteroids or comets on the spacecraft.

2. Drawing Conclusions: The orbit would be mostaffected when Neptune is near Uranus.

3. Summarizing/Synthesizing: The greater themass of an object, the more gravitational forceit exerts on another object. Because Earth islarger than the Moon, a person weighs moreon Earth than on the Moon.

Activity 5 ______________________ page 5New Insulation for Space Shuttles

1. Evaluating Information: Because extremechanges in temperature, as well as the stress oflaunching, cause the tiles to contract or expand,they could bend, break, or become detached.

2. Recognizing Cause and Effect: As the first partof the shuttle breaks through the atmosphere, itis exposed to the most friction.

Activity 6 ______________________ page 6The Appeal of Perpetual Motion Machines

1. Comparing and Contrasting: We assume that anideal machine is a frictionless machine and thatno energy is converted to heat. In such a machine,work input equals work output. In a perpetualmotion machine, the expectation is that workinput will be enough to sustain work output overtime and that there will be no energy lost.

2. Examining and Evaluating Assumptions: Theassumption was that once the initial work wasput into the machine, it would continue work-ing indefinitely. However, the law of conserva-tion of energy suggests that you can never getmore out of a machine than you put in to it.A shift is needed from an ideal (nonexistent)machine to actual devices with moving parts.The devices in these machines had many mov-ing parts that would have lost much energy tofriction. Thus, work input would have beengreater than work output rather than the otherway around.

Answer KeyCritical ThinkingProblem Solving

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

25

Activity 7 ______________________ page 7Stonehenge—An Engineering Marvel

1. Comparing and Contrasting: A bulldozer couldraise the sarsens. A crane could raise the lintels.Using these machines, a single worker couldaccomplish this task.

2. Observing and Inferring: Yes; simplemachines have been used for thousands ofyears, and their proper application could haveaccomplished this. No; it would be too difficultto recruit enough workers. Accept all reason-able answers.

3. Summarizing/Synthesizing: Answers will vary.Students might say that a leader recruited vol-unteers to work on the project or that commu-nity members were required to work a certainamount of time on it. Plans might have beenmade to determine placement and size of thestones. Then stones would have been locatedand carried. Next, moving equipment wouldhave been built and taken to the stones beforetransportation could begin.

Activity 8 ______________________ page 8Energy-Saving Refrigerrators

1. Examining and Evaluating Assumptions: Stu-dents should choose an appliance that theythink could be made more energy efficient.They should list at least two methods theywould use to help them determine whethertheir assumption was correct. They might sug-gest comparing that appliance to similar appli-ances that are older or newer; trackingelectricity bills; or measuring the output oftwo similar appliances, such as the amount ofelectricity it takes to do a single load of laun-dry or any other reasonable test.

2. Generating and Assessing Solutions: 8.034cents ✕ 900 kWh/year = $73.00

Activity 9 ______________________ page 9Radon Risk

1. Observing and Inferring: Houses that relydirectly on groundwater are at greater riskbecause the radon does not have time to dissi-pate before the water enters the house.

2. Evaluating Information: Ventilating the base-ment is a good way to reduce radon buildup

because it prevents the radon from collecting inhazardous concentrations. Ventilation allows theradon to mix with outside air, and radon in theopen air poses little risk.

3. Summarizing/Synthesizing: The safest loca-tion for a house would be in an area withclayey soil. The area should not be dependenton groundwater.

Activity 10______________________ page 10What’s the difference?

1. Observing and Inferring: physical: there are nonew compounds in boiling water; physical:there are no new chemicals in freezing rain;physical: friction prevents slipping on ice; chem-ical: reaction produces new end-products, suchas carbon monoxide; chemical: hydrated coppercarbonate is formed; physical: water in breathbecomes visible vapor; chemical: lactic acidforms; physical: carbon dioxide that was underpressure escapes solution; physical: hands staywarm with energy from friction.

2. Drawing Conclusions: The bleaching action oflactic acid and sunlight is a chemical reaction thatchanges the molecules that cause color in the fab-ric. Today, you might use a chlorine bleach.

Activity 11______________________ page 11Ancient Mysteries and Carbon-14 Dating

1. Examining and Evaluating Assumptions:Assumptions: (A) The original amount of car-bon-14 in the artifact is known. (B) The materialcan take in carbon-14 while it is alive but notwhen it is dead. (C) The rate of decay is constant.(D) The amount of carbon-14 can be measuredaccurately from the artifact. Reasons will vary and might include that the original amount is not really known, the organism might take in carbon-14 after death, the decay rate could varywith location, and carbon-14 can be more accu-rately measured in some artifacts than in others.

2. Making Inferences: Radiocarbon dating canbe used only for materials that are not olderthan 50,000 years. Dinosaurs lived more than65 million years ago. Bones from the era needto be dated by using the age of the rock theyare found in.

Answer Key (continued)

26

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

Answer Key (continued)

Activity 12______________________ page 12Pollution Goes Underground

1. Examining and Evaluating Assumptions:Answers will vary, but students might refer tothe fact that people thought natural filtrationwould prevent serious pollution. Also, becausegroundwater sites are so far underground, peo-ple were unable to see the effects of pollution asthey do in surface waters, such as rivers andstreams.

2. Generating and Assessing Solutions: Studentsmight say that they would advise the commit-tee that the landfill should not be located closeto a shallow groundwater area. Other recom-mendations might include that the landfillshould rest on rock that is not too porous, andthat it should be lined with a material that isimpermeable to water.

Activity 13______________________ page 13The Birth of an Element

1. Recognizing Cause and Effect: Lead has anatomic number of 82 and nickel has an atomicnumber of 28. The sum of the two numbers is 110.

2. Extrapolating Data/Information: Studentsshould choose any two solid, metal elementswhose atomic weights add up to 129. Exam-ples: silver 47 and lead 82; palladium 46 andbismuth 83

Activity 14______________________ page 14Gasoline—Finding a New Formula

1. Clarifying Issues: Answers will vary. Studentsshould recognize that the benefits and draw-backs of using each additive must be considered.

2. Making Predictions or Interpretations: Stu-dents should consider the impact of the RFGprogram on each of these groups. Auto manu-facturers were probably relieved that the finan-cial burden of developing new technology wasbeing shared by another industry. Ethanol pro-ducers would welcome the program, especiallyif the EPA recommended that their product beused in the gasoline over another product,increasing their profits. Oil companies would bethe least enthusiastic because of the money andresearch involved in developing RFG options.

Activity 15 ______________________ page 15Building Materials of the Future

1. Making a Hypothesis: Based on the appear-ance of each chain in the three illustrations,students should conclude that the networkpolymer structure would likely be strongest.

2. Comparing and Contrasting: Answers willvary. Suggestions might include buildings orother structures or medical implants. Advan-tages might include that plastics do not rust,rot, or break down as quickly as metal, wood,or concrete.

Activity 16______________________ page 16Acid Precipitation Report Card

1. Distinguishing Relevant from Irrelevant Facts:Answers will vary. Students should recognizethat the scientist probably had to eliminateother probable causes for the damage to plantlife. After he pinpointed precipitation as a possi-ble cause, he had to find out what it contained.He also had to identify the source of the conta-mination.

2. Observing and Inferring: The Northeast; studentsshould mention the number of vehicles and indus-tries as the probable cause.

Activity 17______________________ page 17Environmentally Friendly Cars

1. Developing a Perspective: Answers will vary.Yes; less pollution, easier to maintain; No; tooexpensive, too small, limited range betweenrecharging, lack of recharging areas other thanthe home, travel distances too short

2. Generating and Assessing Solutions: Possibleanswers include providing tax breaks to peoplewho buy electric and hybrid cars and to com-panies who build them, supporting research,providing education on the benefits of electriccars, and passing laws that require the use ofelectric cars in cities.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of t

he M

cGra

w-H

ill C

ompa

nies

,Inc

.

27

Activity 18______________________ page 18Pole Reversal

1. Examining and Evaluating Assumptions:These sensing devices would probably containiron, a magnetic element found in living things.The iron could contain magnetic domains thatline up with Earth’s magnetic field and help theanimals navigate in some way.

2. Recognizing Cause and Effect: If the driversused an ordinary compass, the reading wouldnot indicate true north. In the far north, theseparation between true north and magneticnorth becomes very great, possibly too great touse a compass as a navigational aid.

Activity 19______________________ page 19Patient-Friendly Cancer Treatment

1. Drawing Conclusions: Much like traditionalcancer treatments, the cancer-fighting weaponhas a better chance of hurting healthy tissuesand organs if it stays inside the body too longbefore finding its cancerous target.

2. Extrapolating Data/Information: Targetedradiation inside the body rather than outsidecould relieve the pain of arthritis, stop bleedingin a hemophiliac, or help keep arteries clear ina patient with heart disease.

Activity 20 ______________________ page 20Regulating Nuclear Power Plants

1. Developing a Perspective: Yes; while weshould continue to develop other forms ofalternative energy, we should also explore thesafe use of nuclear energy. No; the risks ofradiation from nuclear power plants are toogreat to allow nuclear energy to be used.

2. Developing a Perspective: Yes; the nuclearplant would reduce the emission of green-house gases and supply electricity safely.No; the nuclear plant conversion would beexpensive and pose the threat of radiationleakage.

Activity 21______________________ page 21Supersonic Impact

1. Recognizing Cause and Effect: The aircraft aretraveling ahead of the sound they make.

2. Drawing Conclusions: If a meteor that couldcause damage is approaching Earth, people canbe warned before impact.

Activity 22______________________ page 22Treating Cancer with Light

1. Making a Hypothesis: To activate the drug,the laser’s light must come into contact with it.The cancer cells in the middle of a thick tumormight be blocked from the light of the laserand never be affected.

2. Comparing and Contrasting: Plants use spe-cific wavelengths of light to change chemicalconfigurations just as lasers do in PDT. Inplants, pigments absorb light. In PDT, it is thedrug that absorbs light.

Activity 23______________________ page 23Swimming with Sharks

1. Extrapolating Data/Information: Answerswill vary. Examples might include boat hulls,fishing nets, or swim fins.

2. Generating and Assessing Solutions: Studentsshould select one sport and suggest an article ofclothing or a piece of equipment that could bedesigned to help to improve an athlete’s perfor-mance in that sport.

Answer Key (continued)