Download - SF2 Text Book

5/27/2018 SF2 Text Book

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Sydney, Melbourne, Brisbane, Perth andassociated companies around the world

Kerry Whalle

Carol Nevill

Geoff Phillip

Faye Jeffer

Karin Johnston

Peter Roberso

Greg Rickar


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Pearson Education AustraliaA division of Pearson Australia Group Pty LtdLevel 9, 5 Queens RoadMelbourne 3004 Australiawww.pearsoned.com.au/schools

Offices in Sydney, Brisbane and Perth, and associated companiesthroughout the world.

Copyright Pearson Education Australia 2005First published 2005

All rights reserved. Except under the conditions described in theCopyright Act 1968 of Australia and subsequent amendments, nopart of this publication may be reproduced, stored in a retrievalsystem or transmitted in any form or by any means, electronic,mechanical, photocopying, recording or otherwise, without theprior permission of the copyright owner.

Designed by Polar DesignEdited by Writers ReignIllustrated by Wendy Gorton and Bruce RankinPrepress work by The Type Factory

Set in Melior 10 ptProduced by Pearson Education AustraliaPrinted in Hong Kong

National Library of AustraliaCataloguing-in-Publication data:

Science Focus 2.

Includes index.For secondary school students.

ISBN 0 1236 0445 1.

1. Science - Textbooks. I. Whalley, Kerry.

500

ii


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UNIT

UN

IT

UN

IT

UNIT

UNIT

5 Electricity

5.1 Static electricity

5.2 Moving electricity

5.3 Using electricity Science focus:Solar challenge

Chapter review

6 Ecology

6.1 Ecosystems

6.2 Physical attributes of an ecosystem

6.3 Food chains and food webs:

interactions of life

6.4 Effects of human civilisation on

the ecosystem

Science focus:The right balance

a human problem Chapter review

7 Plant systems

7.1 Plant transport systems

7.2 Photosynthesis and respiration

7.3 Leaves

Chapter review

8 Astronomy

8.1 Space rocks

8.2 The night sky

8.3 The Milky Way and other galaxies

8.4 Satellites and remote sensing

Chapter review

9 Team research project

9.1 Teamwork and topics

9.2 Planning your investigation

9.3 Testing and evaluation

Chapter review

Index

Acknowledgements iv

Introduction v

Curriculum grids viii

Verbs 1

1 Science skills 2

1.1 What, why and how? 3

1.2 Scientific research 7

Science focus:Scientific method: the path to

greater understanding 12

1.3 Better measurements 15

1.4 Scientific conventions 22

Chapter review 28

2 Atoms 29

2.1 Elements, compounds and mixtures 30

2.2 Physical and chemical change 38

2.3 Inside atoms 46

Science focus:Atomic models 50

Chapter review 53

3 Microbes 55

3.1 What is a microbe? 56

3.2 Reproduction in microbes 64

3.3 Friend or foe? 70

Chapter review 76

4Body systems

78

4.1 Food 79

4.2 Digestion 89

4.3 Blood and circulation 98

4.4 Excretion: getting rid of wastes 108

4.5 Respiratory systems 111

Science focus:Spare parts 118

Chapter review 122

UNIT

UNIT

UNIT

UNIT


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iv

We would like to thank the following for permission toreproduce photographs, texts and illustrations.

Andromeda Oxford Limited: Based on originalartwork from Ecology & Environment: The Cyclesof Lifeby Sally Morgan, Oxford University Press NYAndromeda Oxford Limited 1995, figure 6.3.4.

Anglo-Australian Observatory / David MalinImages: figures 8.2.2, 8.3.1.

ANT Photo Library: B.G. Thomson, figure 6.1.5;M.J. Tyler, figure 6.4.7.

Auscape International Photo Library: AndrewHenley, figure 6.4.6.

Australian Associated Press: figure 2.1.3.

Australian Picture Library:figures 1.3.14, 3.1.6, SF6.1a, SF 6.1b, SF 6.3, 7.0.1, 7.2.7, 7.3.4; Hulton-DeutschCollection/Corbis, figure 1.1.1a; Hermann/Starke, figure2.2.2; Digital Art, figure 3.1.14; Lester V. Bergman/Corbis, figures 3.2.5b, 4.3.11; Lester Lefkowitz, figure4.0.1; Paul A. Souders, figure 5.1.7; John Carnemolla,figure 6.1.8; Galen Rowell, figure 6.2.5; Jonathan Blair,figure 6.2.7; Michael & Patricia Fogden, figure 6.3.9.

Dr Charles Vacanti: provided by Pearson AssetLibrary, figure SF 4.3.

Coo-ee Picture Library: figure 6.1.4.

CSIRO Publishing:figure 6.1.7, 8.2.8; CSIRO HumanNutrition and The Cancer Council South AustraliaReproduced from 12345+ Food and Nutrition Plan (KBaghurst et al., 1990) by permission of CSIRO Australiaand The Cancer Council South Australia, figure 4.1.4.

Dorling Kindersley: figures 2.1.2c, 5.0.1; MaxAlexander, figure 2.1.2a; Erik Svensson & JeppeWikstrom, figure 2.1.2b; Steve Gorton, 4.3.1; AndyCrawford, figure 4.4.1; Based on original artwork fromNature Encyclopediaby David Burnie, JonathanElphic et al, figure 6.1.2.

Fundamental Photographs: NYC Richard Menga,

figure 2.2.4.Getty: figure 6.1.3.

Global Publishing: Based on original artwork fromAnatomica: The Complete Reference Guide to theHuman Body, figure SF 4.5.

HarperCollins Publishers Ltd:figure 1.3.11.

Dr Ian Jamie:figure 1.1.2.

Kerry Whalley: figures 9.1.3, 9.2.1, 9.2.4, 9.3.1a, 9.3.1b, 9.4.1.

NASA: figures SF 5.3c, 8.0.1, 8.1.1, 8.3.4, 8.3.5, 8.3.68.3.7, 8.4.0, 8.4.6, 8.4.7, 8.4.10, 8.4.11; Glen ResearchCenter, figure 8.4.2.

The National Library of Australia: figure SF 6.5; JoAllcot, figure SF 6.4.

Oxford University Press: copyright from The YouOxford Book of Ecologyby Michael Scott (OUP, 199reprinted by permission of Oxford University Press,figure 6.4.2.

Pearson Education Australia: Anna Small, figures2.2.1, SF 5.3a; Elizabeth Anglin, figures 1.1.4, 2.1.5,2.1.11c, 3.1.3, 3.1.9, 3.1.15, 3.3.2, 3.3.3, 3.3.6, 4.1.1,4.1.2, 4.1.3, 4.3.22, SF 5.1, SF 5.3d, 8.1.3; Karly Aberyfigures 3.1.10c, 3.3.1; Kim Nolan, figure 3.3.8; TriciaConfoy, figure 2.2.3.

Photolibrary:figures 1.1.1b, 1.1.1c, 2.0.1, 2.1.2d, 2.12.3.3, 3.0.1, 3.1.4, 3.2.8, 3.3.9a, 3.3.9b, 3.3.9c, 4.3.4,4.3.6, 4.3.19, 4.4.4, 5.2.9, 6.1.6, 6.2.1, 6.2.4, 6.3.10,7.1.7, 7.2.1, 7.2.2, 7.3.2, 8.1.2, 8.1.4, 8.1.5, 8.1.7, 8.2.48.2.6, 8.3.3, 8.4.5, 8.4.9, 9.2.2; Graham J. Hills, figure2.1.8; Dr Tony Brain & David Parker, figure 3.1.1;Samuel Ashfield, figure 3.1.2; Jackie Lewin, EM UnitRoyal Free Hospital, figure 3.1.8; Susumu Nishinaga,figure 3.1.10d; Sinclair Stammers, figure 3.1.11; Astri& Hanns-Frieder Michler, figure 3.1.12a; Laguna Desifigure 3.1.12b; David Scharf, figure 3.2.1b; ClaudeNuridsany & Marie Perennou, figure 3.2.4; Jean-Loup

Charmet, figure 3.3.5; John Heseltine, figure 3.3.7;National Cancer Institute, figure 4.3.2; Du Cane MediImaging Limited, figure 4.4.2; Alred Pasieka, figure4.5.2; Klaus Guldbrandsen, figure SF 4.2; James KingHolmes, figure SF 4.4; Volker Steger, figure 6.3.5; SheTerry, figure 6.3.8; Dr Jeremy Burgess, figures 7.1.3,7.2.4; St Marys Hospital Medical School, figure 9.3.2

Skymaps.com: figure 8.2.7.

Thomson Learning:Based on original artwork fromThe Joy of Chemistry, 1st Edition 1976, reprintedwith permission of Brooks/Cole, an imprint of the

Wadsworth Group, a division of Thomson Learning,figure 1.3.9.

World Solar Challenge: figures SF 5.6a, SF 5.6b, SF5.6c.

Every effort has been made to trace and acknowledgecopyright. However, should any infringement haveoccurred, the publishers tender their apologies andinvite the copyright owners to contact them.


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Coursebook

The coursebook consists of nine chapters with the

following features.

Chapter opening pages include:

the key

prescribed

focus areafor

the chapter

outcomes

presented in

a way that

students

can easily

understand

pre quiz

questions

to stimulate

interest and test

prior knowledge.

Chapter unitsopen with a context to encourage

students to make meaning of science in terms oftheir everyday experiences. The units also reinforce

contextual learning by presenting theory, photos,

illustrationsand science focus segments in a format

that is easy to read and follow.

Each PFAhas one Science Focusspecial

feature which uses a contextual approach to focus

specifically on the outcomes of that PFA. Student

activities on these pages allow further investigation

and exploration of the material covered.

The Science Focusseries has been written for the NSW Science syllabus, stages 4 and 5. It includes material th

addresses the learning outcomes in the domains of knowledge, understanding and skills. Each chapter address

at least one prescribed focus area in detail. The content is presented through many varied contexts to engage

students in seeing the relationship between science and their everyday lives. By learning from the Science Foc

series students will become confident, creative, responsible and scientifically literate members of society.

Each unit ends with a set of questions. These

begin with straightforward checkpoint questionsthat build confidence, leading to think, analyse

and skills questions that require further thought an

application. Questions incorporate the syllabus ver

so that students can begin to practise answering

questions as required in examinations in later years

The extension questions

can be set for further

exploration and assignment

work and include a variety

of structured tasks including

research, creative writing

and Internet activitiessuitable for all students.

Extension questions cater

for a range of learning

styles using the multiple

intelligences approach, and

may be used for extending

more able students.


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Online review questions

Auto-correcting chapter review questions can be

used as a diagnostic tool or for revision at schoo

or home, and include:

multiple choice

labelling

matching fill in the blanks.

vi

Companion Website

The Companion Website contains

a wealth of support material for

students and teachers, which has been written to

enhance the content covered in the coursebook.

Destinations

A list of reviewed websites is available

these relate directly to chapter content

for students to access.

Technology activities

These are activities that apply and review

concepts covered in the chapters. They are

designed for students to work independently, and

include:

animations to develop key skills and knowledgea stimulating, visual way

drag-and-drop activitiesto improve basic

understandings in a fun way

interactives to enhance the learning of content i

an interactive way.

Key numeracy and literacy tasks are

indicated with icons.Practical activities

follow the questions.These are placed at the

end of the unit to

allow teachers

to choose when

and how to best

incorporate thepractical work.

Cross-referencesto practical

activities within

the units signalsuggested points

for practical work. Some

practical activities are design-your-own (DYO) tasks.

Chapter review

questionsfollowthe last unit in

each chapter. Thesecover all chapter

outcomes in a

variety of questionstyles to provide

opportunities for

all students toconsolidate new

knowledge andskills.

The use of the Aboriginal flag in the coursebook

denotes material that is included to cover Aboriginal

perspectives in science.

DYO

Prac 1Unit 1.2


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Homework Book

The Homework Book provides a structured program

to complement the coursebook. These homework

activities:

cover various skills

required in the syllabus

offer consolidationof keycontent and interesting

extension activities

provide revisionactivities

for each chapter,

including the construction

of a glossary

cater for a multiple

intelligencesapproach

through varied activities

have Worksheet icons in the coursebook to

denote when a homework activity is available.

Teacher resource centre

A wealth of teacher support material is provided an

is password-protected. It includes:

a chapter testfor each chapter, in MS Word to

allow editing by the teacher

coursebookanswers

Homework Bookanswers teaching programs

Teacher resource pack

Material in the teacher resource pack consists of a

printout and electronic copy on CD. It includes:

curriculum correlation grids mapped in detail to

the NSW syllabus

chapter-based teaching programs contextual teaching programs

coursebook answers

chapter tests in MS Word

Homework Bookanswers.

Worksheet 1.5 Sci-skills crossword

Worksheet 4.3 The heart


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viii

A fully mapped and detaile

correlation of the stage 4

curriculum outcomes is

available in the Science Fo

Teacher Resource.

Note: indicates the Key Prescribed Focus Area covered in each chapter.Chapters may also include information on other Prescribed Focus Areas.

Science Focus 2 Stage 4 Syllabus Correlation

chapter

outco

mes4.1

4.2 4.3 4.4

4.5

4.6

4.7

4.8 4.9 4.10

4.11

4.12

4.13

4.14 4.15 4.16 4.17 4.18 4.19 4.20 4.21 4.22 4.23 4.24 4.25 4.26 4.27

2 456789Atoms1Science

skills 3MicrobesBody

systemsElectricity Ecology

Plant

systemsAstronomy

Tea

resea

proj


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Extrapolate infer from what is known

Identify recognise and name

Investigate plan, inquire into and draw conclusions

Justify support an argument or conclusion

List write down phrases only, without furtheexplanation

Modify change in form or amount in some way

Outline sketch in general terms; indicate the mafeatures of

Predict suggest what may happen based on avainformation

Present provide information for consideration

Propose put forward (eg a point of view, idea, arsuggestion) for consideration or action

Recall present remembered ideas, facts orexperiences

Record store information and observations for l

Recount retell a series of events

Research investigate through literature or practicainvestigation

State provide information without further expSummarise express concisely the relevant details

Verbs

Science Focus 2uses the following verbs in thestudent activities.

Account account for: state reasons for; report ongive an account of: narrate a series of eventsor transactions

Analyse identify components and the relationships amongthem; draw out and relate implications

Apply use, utilise, employ in a particular situation

Assess make a judgement of value, quality, outcomes,results or size

Calculate determine from given facts, figures or information

Clarify make clear or plain

Classify arrange or include in classes/categories

Compare show how things are similar or different

Construct make; build; put together items or arguments

Contrast show how things are different or opposite

Deduce draw conclusions

Define state meaning and identify essential qualities

Demonstrate show by example

Describe provide characteristics and features

Discuss identify issues and provide points for and/oragainst

Distinguish recognise or note/indicate as being distinct ordifferent from; note differences between

Evaluate make a judgement based on criteria; determinethe value of

Examine inquire into

Explain relate cause and effect; make the relationshipsbetween things evident; provide the whyand/or how


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>>>

By the end of this chapter you should beable to:

ask questions that can be tested orinvestigated

plan investigations, identifying what

type of information or data needs to becollected and why

identify variables that need to becontrolled

identify dependent and independentvariables in experiments

plan a procedure for performing a fairtest

perform experiments and recordobservations and measurementsaccurately

organise data in various forms, includingtables and graphs

identify relationships, patterns andcontradictions in information and data

analyse results

comment on the accuracy and meaningof observations and results.

1 What is a scientist?

2 Name as many different areas of work

done by scientists as you can.3 How do scientists go about their work?

4 What is a variable?

5 How do scientists ensure that their workis accurate?

6 How do scientists communicate theirideas to each other?

Outc

omes

4.2,

4.1

3,

4.1

4,

4.1

5,4.1

7,

4.1

8,

4.1

9

Prequ

iz

11

Science skillsScience skillsKey focus area:

The nature and practice of science>>>


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Asking questionsScientists ask What, why

and how? about the naturalworld. Whatprotects some

people from catching chicken

pox? Whyis the sky blue, not

green? Howdo birds know the

direction in which they should

migrate? Whydid the chicken

cross the road? They also ask

How does this information

connect with the information

we already know?.

We live in a technological world where we use

machines and equipment every day. Most of us hav

no idea how these work, but someone invented them

and others improved them so that they became sma

cheap and reliable enough to have in homes, school

factories, farms and businesses.

Scientists ask What, why

and how? when they want

to invent something new or

improve current technology.

Whatcauses poor receptionon your TV? Whydoes your

computer crash? Howcan

we make an alarm that alerts

a surgeon that a patient

is waking up during an

operation?

The answers to these

questions can sometimes be

found in written resources

such as textbooksor the

Internet. Other answers can

be found out only by doingfirst-hand investigationsor

experiments. This is the job

of a scientist.

UNITUNIT

1.11.1The world often seems to be a very confusing

place: there seem to be so many mysterious

things going on around us. Albert Einstein

said that the job of scientists was to

coordinate our experiences of the world and

try to fit them into some logical system.context

Prac 2p. 6

Prac 1p. 5

Fig 1.1.1 You may have heard about Einstein, and Newton, but what did aHoward Florey, bMarie Curie and cCharles Darwin do?Which of them was Australian?

Poisoned!

SirIsaacNewton(16421727)

developedmanylawsin

scienceandmathematics, but

spentmuchofhistimewith

theancientart of alchemy.He

wastryingtochangecommon

metalsintopuregold!Other

scientistsoftenfoundNewton

extremelychildishanddifficult

toworkwithanditisnow

thoughtthatthefumesfrom

hisalchemyexperimentswere

slowlypoisoninghim.Inthe

laboratoryscientistsmusttake

carewiththechemicalsthey

use,particularlyfumes.What

rulesaboutchemicalsshould

youobeyinthelaboratory?

NewerbutnotThescientistsof thee

industryusuallyaimtpartsthataresmalleandmorepowerful. Thowever,agrowingdethelargeandclumsyold.ToprecordingstudusethemsinceitisthosoundqualityisbettermodernelectroniccomTheradiationfromX-

knockoutmodernelectmedicallaboratoriesusekeepequipment runningaircraft often

usevalvesbeingknockedoutoftradiationfromapossibl

explosioninwar

a b c


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8 Recordthe

measurement shown

on each of the

micrometer scales

illustrated

at right.

9 Draw the shaftand barrel of a

micrometer showing

a measurement of

12.87 mm.

Fig 1.1.2

4

What, why and how?What, why and how?

1.1

UNIT

[ Questions ]Checkpoint

1 Listthree things about the natural world that confuse

you.

2 Constructa what, why and how? question about each

of the things that confuses you.

3 Describehow you would go about finding an answer to

each of your questions.

4 Contrastthe methods you listed in question 3 with the

methods used by workers who arent scientists.

Think

5 Constructa two- or three-frame cartoon that explains

how to use a micrometer. Hint: Check Prac 1 on page 5.

6 Statewhether the following statements are true or false.

a Scientists carry out experiments on what confuses

them about the world.

b A micrometer is used to measure thick objects.

c The barrel of a micrometer usually has markings from

0 to 100. Hint: Check Prac 1 on page 5.

d The measurements that you control should always go

on the vertical axis of a graph.

e Points on a graph should be joined up dot-to-dot.

Skills

7 Constructa diagram of a micrometer and label the

parts.

[ Extension ]Investigate

1 There are many other instruments that can measure

small quantities very accurately. Researchinformatioon:

a other devices that are used to measure thicknesse

and distances accurately

b how the worlds most accurate clock works

c how very small quantities of chemical pollutants a

measured

d how small signals from space are amplified so th

they can be measured.

2 Researcha vernier caliper to find out what it measur

and how its scale works. Include a diagram and

description in your response.

3 Some scientific discoveries, such as the discovery ofpenicillin, are made by accident.

a Researchthe discovery of penicillin and describe

who discovered it, when and how; what it is used

for and its importance to society.

b Imagine that you are the person who

discovered penicillin. Write a letter to the

Royal Society of Medicine outliningyour discover

Fig 1.1.3

5 10

55

50

45

40

10 15

80

75

70

65

30 35

25

20

15

a

b

c

AsheepsburpWhenasheepfartsor burps,it releasesmethane,agreenhousegasthatcontributestoglobalwarming. Eachsheepreleases

about 25litresofmethaneeachday!CSIROscientistsdesignedthedeviceshowninFigure1.1.2.tomeasuretheamount of gasemittedwithoutharmingthesheep.Thisdeviceistheresult of scientistsasking:

Whatistheproblem?Whyisitoccurring?Howarewegoingtosolveit?


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[ Practical activities ]1.1

UNIT

A useful tool:the micrometer

AimTo use a device that can accurately measurethe thickness of objects to within a fraction of

a millimetre

Equipment

Micrometer, various common school items

shaft readsbetween26 and 27

barrelreads32

10 15 20 25

40

35

30

25

Fig 1.1.5This micrometer reads 26.32 mm.

Creative writing

The big flash!

A massive and blinding white light blasts planet Earth.

You get up and go to school the next day, but something

odd happens in Science. The pages in your textbookand workbook are all blank. Your Science teacher just

mumbles, not knowing what to say. That night there are

news reports of scientists going to their laboratories

having no idea why they are there. It seems that all the

scientific knowledge of the world has been erased and

needs to be learnt again. In a piece of writing explain what

troubles humans will get into in the next week without any

idea of science, its inventions or how the world works.Write it as either:

an essay

a series of newspaper front pages

a timeline starting from the big flash.

barrel(usually numbered from 0 to 100). Read the

millimetre measurement off the shaft of the micromete

3 Along the shaft is a line. Read off the barrel

measurement where it meets the barrel (it will be a

number between 0 and 100).

4 Use a micrometer to measure the:

thickness of your little finger

thickness of this textbook

thickness of five sheets of paper

diameter of the ball of a ballpoint pen

thickness of a pencil thickness of a coin.

Questions

1 Compareand contrastthe use of a micrometer with t

use of a ruler for the measurements in the experiment.

2 Proposea method in which a normal ruler could be

used for the measurements in the experiment.

Fig 1.1.4 A micrometer

Method

1 To take a measurement, place the object in the opening

of the micrometer and screw down the barrel until the

knob starts to slip. Do not overtighten; you dont want to

squash the object.

2 There are two measurement scalesone on the shaft(in

millimetres just like a ruler) and another on the rotating

Prac 1Unit 1.1


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>>>

6

Does nature follow

rules?

Aim To investigate how a tree grows and see if it

follows any rules of natureEquipment

1 m ruler/tape measure, micrometer, permanent marker or

chalk

Method

1 Collect a branch or long twig from a tree, preferably an

old twig from the ground. The branch needs to be 80 cm

to 1 m long and no more than 2 cm thick at its base. It

should not be broken off before its small end.

2 Strip the branch of any side twigs and leaves.

3 Make ten regularly spaced markings with the permanent

marker or chalk along the length of the branch. The

spacing must be the same for each marking, so youshould make them 8 to 10 cm apart.

Prac 2Unit 1.1

8 to 10 cmregular spacing

markings

twig micrometer

Fig 1.1.6 Checking if there is a growth rule

4 Constructa table or

spreadsheet like that

shown opposite.

You need 11 lines.

Distance of marking Diameter or thickness Average diameter or(cm) (mm) thickness (mm)

5 Use the micrometer to measure the thickness of the

branch at each marking.

6 Have all partners in your group measure the diameters

at each marking too. 7 Cross out any measurements that are very different fro

the rest, then calculate the average diameter for each

marking.

Questions

1 Identifywhich set of measurements, Distance along

the branch or Diameter of the branch, is the controlle

measurement.

2 Plot the controlled measurements on the horizontal axi

on a sheet of graph paper. Markings along each axis

should be equal and evenly spaced. Each axis should

have a label and correct units.

3 Constructa line graph to show your results.

What, why and how?What, why and how?

4 Assesswhether there is a pattern to

nature by examining whether the graph

obtained approximates

a smooth curve or a straight line.

5 Are there some points on the graph that

are out of pattern? If so, examine the tw

used in the experiment and proposea

reason for them being outfor examp

there may be a split, knot or side branch

at that spot.


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Scientists generally do not perform just one

experiment: they usually carry out many

experiments, all of them investigating the

one topic. These experiments are often done

by a team of people all collecting different

pieces of information to help solve a puzzle.

This is called scientific research. Research can

take a long time as experiments do not always

context

UNITUNIT

1.21.2give the desired results the first time. It can take

many years just to make a simple discovery. Many

discoveries occur by chance, as a scientist notices

something unusual and tries to work out what it was

Scientific research requires great patience, persisten

and creativity.

The research journeyResearch normally starts with observations made in

everyday life or maybe by accident. An observation

is a fact and can be either qualitative(described

and written down in words only) or quantitative

(measured and stated as numbers).

There is no guesswork in observations. You use

your fives senses to observe and

record observations accurately.

You should check your

observations a number of times

to be sure you have not made

any errors. The recording and

reporting of your results will

allow other scientists to repeat

your research.

Observations lead to

questions about what was

observed.

Look at the following

problem that confronted a

Year 8 student during the

last school holidays. His

observations led to thequestions what, why and

how?.

Carl and his friends went camping for a week over the school

holidays. When they collapsed the tent to go home Carl found

that the grass under the floor of the tent had gone a yellow-

white colour and was dying. Carl wondered what had caused

the apparent death of the grass.

When scientists are confronted with a problem

they make logical explanations or inferencesabout

what they observed.

Carl and his friends thought about it carefully. They came u

with a list of factors that may have affected the grass in the

week it was covered by the tent.

It was trampled badly in the week.

It didnt like the black colour of the plastic tent floor.

It received no water.

It didnt receive any sunlight.

It didnt like the smell of his socks when he took them o

at night (all his mates complained about that too!).

Observation: grass goes yellow-white in colourwhen it is covered.

Ancientobservations

Intheyear5BCChineseastronomersnotedthattherewasastarburningwithunusual brightnessfor70days.Whattheysawwasprobablytheexplodingstaror

supernovaAquilae.Manybelievethat 5BCwasalsotheyearofthebirthofJesusChrist.WasthestarthatledthethreewisementoBethlehem

actuallythesupernovaseeninChina?


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8

>>>

Scientists also try to fit the new observation with

what they know already about similar situations.

Carl knew from his science classes that plants need sunlight

and carbon dioxide gas from the air to make energy and stay

alive. A lack of carbon dioxide was another possible factor.

These factors are known as variables.

Some of Carls variables were downright silly. After

thinking more scientifically about it, Carl decided

that the most important factors were the lack of

sunlight and water. But which one of these was

more important?

Scientists then make a hypothesis, a prediction

or educated guess about what they might find

in an experiment or what might have caused the

observations. A hypothesis is something that can be

tested by an experiment.

Carl thought that the lack of sunlight was probably the most

likely reason the grass was dying. This was his hypothesis.

Scientists then develop questions regarding the

problem. These questions can become the aim for

experiments.

Carl planned two experiments.

In the first he tried to find out if a lack of water would

cause the grass to die in a week.

In the second he asked, Does a lack of sunlight kill grass

in one week?.

These were the aims of his experiments.

Good scientists run fair tests. They carefully plan

their experiments so that only one variable will be

Fig 1.2.2Factors that might have affected the grass

Prac 1p. 10

tested at a time. Otherwise they would not be able

to work out which variable caused the effect. The

variable that is changed in an experiment is also

known as the independent variable.

Scientists ask four questions when they are

planning an experiment. What is being tested? (the aim)

What is being changed? (the independent variab

What is going to be kept the same? (the controlle

variables)

What is going to be measured or

recorded? (the dependent variable)

The results obtained dependupon what

we change. Therefore what we measure or

record is called the dependent variable.

Carl grew four identical patches of grass. The same type a

amount of grass was in each patchthe controlled variableIn each experiment he was careful to change only one varia

at a time, keeping everything else the same.

Experiment 1: Carl watered

two pieces the same. One

patch was left in the sun (this

one is called the control)

and the other was covered by

black plastic.

Experiment 2: The other two

patches were placed side

by side in the sun. One was

watered regularly (the control)

while the other was kept dry.

Carl found that a lack of

water made the grass go brown,

not yellow.

The lack of sunlight caused

the grass to first go yellow, with

some blades then turning white.

These were his observations.

From observations and

measurements, a conclusion

can be made that should

prove the hypothesis to beright or wrong.

Carls conclusion was that the

grass died because of a lack

of sunlight. His hypothesis

seemed to be correct.

Pracp. 1

Scientific researchScientific research

DidscientistscreaAIDS?

AviruscalledSIVhasalwinfectedthemonkeysofAfbuttheynever becameillfit.Most scientistsbelieve

sprangfrommonkeytohufromascratchorfromeatinfectedmonkeymeat.ThethenmutatedtobecomeHIVvirusthatcausesAIDS. Sothink,however, thatinfectemonkeykidneyswereuseinthedevelopmentofapovaccinecalledCHAT. Poliowdevastatingtheworldinth1950sandtheexperimentaCHATvaccinewasgiventthousandsof peopleinAfribetween1957and1960.Thfirst outbreaksofAIDSwere

thesameregionthatthevaccwasgiven, thefirstdeathbeiin1959. DidtheCHATvaccicausetheAIDSoutbreak?

Didscientiststakeenoughcaintheir research?Asscientiswehavearesponsibilityto

takeextremecareineverythinwedo.


17/259

1.2

UNIT [

Questions]Checkpoint

1 Definethe following terms:

a observations d hypothesis

b qualitative e variable

c inference f controlled variable.

2 Statewhether the following statements are true

or false.

a Research is a number of experiments run on the

same topic.

b Observations involve guesswork.

c A hypothesis can be tested with an experiment.d A variable is the same as an inference.

e The grass is yellow is a qualitative observation.

f The grass grew

5 mm in a day

is a qualitative

observation.

g Controlled

variables are

variables that are

not changed in an

experiment.

3 Listthe three

questions regarding

well-designed

experiments

that need to be

addressed.

4 Explainwhy only

one variable should

be tested at a time.

Think

5 You arrive home after a large storm and notice that the

television set isnt working. There is a puddle of water

on top of it and another underneath it.

a Summariseyour observations.

b Describeinferences you can make from the

observations.

c Predictwhat may happen to the television set and

the house.

6 Fi and Cathy were in an egg-and-spoon race (see

Figure 1.2.4).a Identifythe variables in the race.

Fig 1.2.3Controlling variables in an experiment

Fig 1.2.4

>>

Worksheet 1.1 Carls new experiments


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10

>>>

[ Practical activities ]

UNIT

Happy birthday to you!

AimTo observe and interpret what happenswhen a candle is burnt in a sealed space

Equipment

68 birthday candles and matches, plasticine or

Blu-tack, 2 elastic bands, a shallow pan, 1 gas jar

or tall narrow drinking glass

Method

1 Construct a two-column results table or spreadsheetwith the headings Number of candles and Rise in

height (mm).

2 Make a small mound of plasticine or Blu-tack in the

centre of the pan and then fill the pan with water.

3 Stick one candle in the plasticine. Place the gas jar or

glass over the candle.

4 Place one elastic band around the glass at the level of

the water.

Prac 1Unit 1.2


Choose one of the occupations listed below. Research

what areas of science a person would need to know towork effectively and safely in that occupation. Present

your findings as a pamphlet to be displayed in the career

information centre in your school.

Architect

Laser eye surgeon

Chemist

Optometrist

Firefighter

Car mechanic

b Assesswhether it was a fair race.

c Describeways of making it a fair race.

Analyse

7 Referring to Carls experiments on factors that affect the

growth of grass:

a identifythe two variables tested by Carl

b listother variables that could affect the growth of the

grass under the tent

c outlineprevious knowledge used by Carl.

8 Referring to Carls research:

a proposea heading for the research project

b constructan introductory sentence explaining why

the research was being performed

c proposeaims for the research and the two

experiments

d draw conclusions from the two experiments and from

the research project.

Investigate

9 Carl wondered whether the grass under the

tent would die or whether it would recover.

Design a controlled experiment to test a

hypothesis he could make about this extra

question.

DYO

Aircraft refueller

Structural engineer

Nurse

Racing car driver

Pilot

Physiotherapist

Create

10 Im red with a cream-coloured interior. I grow on a tree

and can be eaten. What am I? Select an item from the

categories listed below, describeit and have a partnededuce what it is.

a a food d an animal or insect

b a tool of some sort e a sport.

c a piece of furniture

Scientific researchScientific research

elasticband

water

pan

matches

g

plasticinecandles

REDHEADS

elastic bands

Fig 1.Which variable caused

more water to rise?1.2


19/259

Questions

1 From the list below, identifythe

variable which probably had the

most effect on the change in water

level: the volume or depth of water

in the tray, the height and diameter

of the gas jar, the number or colour

of the candles, the amount of

plasticine or Blu-tack.

2 Identifythe chosen variable and

the controlled variable in this

experiment.

3 Proposereasons for the rise in

water level in the jar.

4 Identifyany trend evident from the

graph which shows a relationship

between the variables you plotted.

Why do cooks add salt

to water?

AimTo investigate why cooks usually add salt towater when cooking vegetables, pasta or rice

Equipment

3 x 100 mL beakers, 100 mL measuring cylinder, Bunsen

burner, bench mat, retort stand, bossheads and clamps,

gauze mat, thermometer, timer, table salt, beam balance or

electronic scale

Method

1 Set up the Bunsen burner with a beaker containing

60 mL of water.

2 Heat the water and record the temperature every

30 seconds until the water boils.

3 Add 2 g of salt to another 60 mL of water and repeat

the experiment with the same Bunsen flame.

4 Repeat with 4 g of salt.

5 Record your results in a table or spreadsheet like this:

Prac 2Unit 1.2

Time (s) Temperature (C)

No salt 2 g salt 4 g salt

0

30

60

Questions

1 Were the observations made qualitative or quantitative?

Justifyyour answer.

5 Remove the jar, light the candle and quickly place the jar

over the candle.

6 Allow the candle to burn until it goes out. Wait a short

while and observe what happens to the water level.

7 Place the other elastic band over the glass at the new

water level. 8 Measure the change in water level and record the

measurements in the table.

9 Repeat the experiment with two, then three, five and

seven candles.

10 Plot a line graph showing what happened to the height

the water rose as more candles were added.

11 Use the graph to predict the water rise for four, six and

eight candles.

12 Run the experiment again for four, six and eight candles

to check your predictions.

2 Based on your observations, deducewhy cooks add

salt to water.

3 Extension: Constructa line graph for the temperatures

recorded without any salt. On the same graph plot

heating curves for the beaker with 2 g and 4 g of salt

added.

thermometer

retort stand

100 mLbeaker

60 mLwater

no saltthen2 g saltthen

4 g salt

Fig 1.2.6Why do cooks add salt?

FlameouWhencandlesbumeltsandsom

vaporisesintoag

flameyouseeisburningwaxvapyoublowthecanatrail of smokewfromthewick.Thiswaxvapour buunburnt.Canyouacandlebysettingitssmoke?Tryligacandle,thenbloit out.Slowlylowmatchdownthestrail.Theflame

jumpdownthesmrelightthecandle

howfaritcanju


20/259

12

Why use the scientific

method?

Humans have always asked questions and sought to

understand the observations they make. This desire

to understand the world around them led the Ancient

Greeks to develop the term scientia(to know) and to

make the first steps towards a study of what we now

call science.Initially people gained an understanding by

simply thinking about a problem and coming up with

an explanation! Over time, however, they began to

want deeper understandings and began to conduct

experiments. Through the work of Galileo and

Newton, the scientific method was formalised and

became the accepted technique for testing and proving

ideas in science. Experiments became so important

because they provided evidence to support the

answers to questions.

Climbing the mountain towardstrue understanding

Figure SF 1.1 indicates how the scientific method

has steadily led to humans gaining an increased

understanding. The quest for knowledge can be

viewed as similar to climbing a mountain.

Starting the climb

As shown in the diagram, at the beginning of the

path up the mountain the scientist asks questions in

an attempt to explain observations or problems. The

scientist comes up with an idea as a possible answerto the question, usually supported by observations

and current knowledge. This idea becomes known as

a hypothesis. Experiments must then be designed to

allow the hypothesis to be tested.

The first and most important

step

Designing the right experiment that will be a valid

test of the hypothesis is a very important skill for a

scientist. The experimentcan be considered the mos

important component of the scientific method becau

a well-designed experiment produces and confirms

results and knowledge that scientists can trust to beaccurate. It provides supportive evidence.

If the experiment produces results that disagree

with the hypothesis, this results in a downward pat

and the scientist must develop a new hypothesis. If

the experiments produce results that agree with the

hypothesis, further experiments are conducted to

continue to test whether the hypothesis is true.

Going up!

If, after many experiments have been conducted

and all have shown the hypothesis to be correct, the

scientist climbs further up the mountain, and the idbecomes a theory. A theory is an explanation of an

idea that is supported by a large amount of evidenc

and testing.

A theory can lead to the development of a mode

Models provide scientists and others with a clearer

way to describe or explain their understanding. A

model might not match exactly what is really going

on, but it can be used to help us understand and

predict what will happen in other situations, just lik

a model of a planned aircraft helps engineers better

understand the real thing.

As models develop and research continues,

the new scientific understandings lead to another

path resulting in technologythat usually improves

our lives.

Science focus:

Scientific method: the path to

greater understanding

Prescribed focus area: The nature and practiceof science


21/259

Law

Technology

released to

benefit humans

Design

and

engineering

Applications

to serve

humans

RESEARCHincluding

mathematical

predictions from

theory or model

New or

contradictory

predictions

Modified

or new

hypothesis

Confirmation

by many

experiments

Hypothesis

supported by

experiments

Hypothesis

not supported

by experiments

New

hypothesis

Idea

hypothesis

Problem,

question,

observation

TheoryModel

Design experimental

test for hypothesis

or prediction

New or

unexpected

observations

New level of

understanding

Greater

knowledge

Model or theory found

to apply and hold true

in many areas of

scientific study

Experiment

Fig SF 1.1A mountain of research: the scientific method


22/259

14

[ Student activities ] 1 a Investigatefurther the meanings of the following

terms: hypothesis, experiment, theory, law, model

b Construct a table to summariseyour findings,

including a definition and example of each term.

2 When discussing the scientific method, many scientis

claim There is no such thing as a scientific fact!.

a Justifythis statement by writing a paragraph to

clarify your ideas.

b Organise a class debate about this topic.

3 The Gravitation Theory developed by Isaac Newton

in the 17th century is still discussed in science

classrooms. Yet, for scientists working in modern

research, Newtons theory has been replaced.

a Based on your understanding of scientific method

proposepossible reasons why Newtons

Gravitation Theory:i is no longer used by scientists doing

research into gravity

ii is still taught in Science classes in

schools.

b Listthe possible reasons you have proposed and

share your findings with the other groups.

c Write a paragraph to presentyour own view and

explainwhy you have made your choice.

4 a Investigateat least three scientific laws.

b Statethe law in the scientific language used in yo

source (be sure to include your reference).

c In your own words constructa simple descriptioto allow you to clearly explain each law to your

classmates.

d Choose one of the laws you have found and

constructa model to help you explain the law

to others.

Sometimes scientists develop a theory that is found

to apply in many areas of scientific research, and is

always proven true in every experiment. These very

significant and important pieces of knowledge and

understanding become known as lawsand provide a

solid base for scientists doing their work.

Slipping down Sometimes, just when scientists think that they have

a full understanding of an idea, the experimentsor

sometimes mathematical predictionsshow that the

theory is not really the whole story, or in some cases,

is completely wrong. This leads to a very steep slide

back down the mountain to the development of a

new hypothesis. This new hypothesis must then go

through scientific method again before it is accepted

as a replacement for old theories.

Onward and upward

The scientific method has its ups and downs, but has

been a powerful tool in increasing our understanding

of the world around us. The strength of this method

is based on the evidence gained from experiments.

The scientific method has allowed us to gain a greater

understanding, which has led to developments that

have improved our quality of life. With continued

research and experiment the quest to reach the top

of the mountain continues.

Fig SF 1.2A scientist in the lab


23/259

1.31.3UNITUNIT

Accurate measurements are often impossible

to make. Estimates are often the best we

can do. If you wanted to know the amount

of water in Sydney Harbour you would need

to estimate it since there is no accurate waycontext

Mistakes and errorsMistakesare things that could have been avoided if

you took a little more care. They can include:

careless reading of a measurement incorrect recording of a measurement

spillage of material

use of the wrong piece of equipment.

Errorsare things that are unavoidable. They are

usually small and are not your fault. Errors will

always happen and it doesnt matter how careful you

are. Nothing is exact. Even accurate measurements

are in fact estimates, all because of errors.

Common errors are:

parallax error

Your eye can never be exactly over the marking of

a measuring device. Everyone looks at markings

at slightly different angles so everyone will take

slightly different readings.

Reduce parallax errors by keeping your eyein line with the measurement.

Fig 1.3.1

of measuring it. The number of people in a shopping

mall would constantly change as people left and

new people arrived. An exact count would be near

impossible.

reading errors

Measurements often fall between the markings o

measuring device. Some estimation is required f

you to take your measurement.

0 cm 1 2 3 4 5 6 7

Fig 1.3.2Not quite 6 cm long, but is it 5.7, 5.8 or

5.9 cm?

instrument errors

Sometimes the instrument

you are using is faulty and

will never give the correct

reading. Some instruments

give correct readings only

at certain temperatures and

will give small errors if used

at any other temperature. A

metal ruler expands when

hot, causing the markings to

move further apart. This makes

measurements taken on a hot

day slightly smaller than those

made on a cold day.

human reaction time

A stopwatch normally reads

to one-hundredth of a second

100millisecon

awayfromdea

Detailedstudies

Saabhaveshown

ahead-oncollisio

acarwithasolid

takeslessthan1

milliseconds, or 0Howdoesthiscom

withyour reaction

Ifless,thenthe

accidentisoverb

youcanreacttoit!

isnochanceofg

ready orbracingto

injuryagoodca

wearingseatbe


24/259

16

>>>

0 cm 1 2 3 4 5 6 7

0 cm 1 2 3 4 5 6 7

metal rulers contract on cold days

metal rulers expand when hot

Fig 1.3.3 Same match, different days, different

measurements

(0.01 s). Humans are not as accurate as this: we

simply cant react quickly enough. Measurements

of time will vary among people because

we all have different reaction times. Data

loggers have faster reaction time than

humans and are more accurate, but there

are still errors involved.

Repeated measurementsBecause errors always exist, people can measure the

same thing differently. So who has taken the correct

measurement? They all have! Unless someone made

a silly mistake there is no wrong answer. Repeating

measurements is a good way to improving accuracy.

Once a collection of different measurements is taken,

an averageor meancan be obtained.

To find an average:

1 add all the measurements together to get a total

2 divide this total by the number of measurements

taken.

Various members of a group measured the length of

a mouses tail and each got different results: Anna 8.1 cm

Lee 8.4 cm

Millai 8.5 cm

Nicole 8.2 cm

Steve 12.9 cm.

Steves result is too far away from the rest of the

results. It looks like he made a mistake so his result

should be ignored.

Prac 1p. 19

To obtain the most accurate measurement it is beto average the other four results; that is, add the fou

results:

8.1 + 8.4 + 8.2 + 8.5 = 33.2

and divide the total by the number of readings:

33.2 4 = 8.3 cm

Notice that no one in the group actually

took a measurement that was the same as

the average.

A little give and takeIt is often useful to

write measurements

with an estimation

of how big the error

might be. We allow a

little give and take

by showing the error

as (standing for

plus or minus). The

exact measurement

shown in Figure

1.3.5 needs a littleguesswork.

Although it looks

as if it should be

about 27C it could

be a little higher or

lower, perhaps as

much as 1C. The

measurement could

Fig 1.3.4Everyone will get slightly differentmeasurements.

Prap. 2

27 1C

0

5

10

15

25

30

35

C

Fig 1.3.5

Better measurementsBetter measurements


25/259

1.3

UNIT

[ Questions ]

6 From the following, identifythe measurements that

could be taken accurately:

a the number of kangaroos in Australia

b the number of kangaroos in the zoo

c the length of the science laboratory at school

d the number of cloudy days in the next monthe the number of students who buy chips at the

school canteen.

7 Classifythe following as either mistakes or errors.

a Mia poured water from a measuring cylinder but

could not get every drop out.

b Kim spilt some of the chemicals he was to use in

an experiment.

c Johnno didnt bother cleaning the dirt off the beam

balance he used.

d Sara found it difficult to decide on measurements

that fell between the markings on a tape measure.

e Michas electronic scale was reading 0.1 g when

empty and he didnt zero it.

Skills

8 Calculatethe average of these values to obtain the

most accurate measurement.

a 39 mm, 38 mm, 40 mm, 41 mm, 40 mm

b 25.3C, 26.8C, 27.5C

c 45 mL, 47 mL, 46 mL, 58 mL (be careful here!)

9 For each example in Figure 1.3.6, describethe type

of error made.

Fig 1.3.6

be written as 27C give or take 1C. Scientists write

this as 27 1C.

The mouse-tail measured earlier averaged

8.3 centimetres even though no one actually

measured it as that. The mouse-tail could be

said to be between 8.1 and 8.5 centimetres.

This could be written as 8.3 centimetres giveor take 0.2 centimetres, or 8.3 0.2 cm.Prac 3p. 20

Checkpoint

1 Comparean error with a mistake.

2 Explainwhy it is difficult to avoid errors.

3 Outlinefour different types of errors.

4 Why do scientists use different procedures to avoid or

minimise errors? Justifyyour answer.

Think

5 Statewhether the following statements are true

or false.

a All measurements are exact.

b An average can also be called the mode.

c A mistake is an error.

d A measurement of 56 2C actually goes from

58C to 56C.

e Human reactions are always fast and accurate.

>>

Worksheet 1.2 Extreme units


26/259

18

>>>

10 a Define.

b Recordthe following measurements with a error.

1

2

3

4

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

mm

0

20

40

60

80100 120 140

160

180

200

220

240km/h

a

c

b

Fig 1.3.7

Fig 1.3.8


1 Conduct research to find the correct operating

temperatures for the following apparatus:

a 250 mL beaker

b 100 mL measuring cylinder

c school electronic balance.

2 Police often give accurate estimates of crowd numbers

at sporting events.

a Explainhow you could determine the number of

people in the photo in Figure 1.3.8 without counting

each person.

b Use your method to estimatethe number of people

in Figure 1.3.8.

3 Use your method to estimatenumbers in the following

examples:

a the number of grains of sand that would fit in a

shoebox filled with sand

b the number of leaves on a tree

c the number of words and individual letters printed in

this chapter.

4 Use the diagram in Figure 1.3.9 to explainthe

difference between accuracy and precision.

5 a Researchand summarisewhat is meant by

the frequency of a pendulum.

b Proposea way of measuring the frequency

of a pendulum.

c Design an experiment to investigateyour

method of measurement.

Action 6 Examineeach of the following instruments to find the

smallest markings or divisions on them:

a digital stopwatch

b normal ruler

c tape measure

d thermometer

e kitchen scale.

DYO



27/259


UNIT

How quickly can

you react?

AimTo find your reaction time

Equipment

Ruler (for most people a 30 cm ruler

will do), access to a calculator

Method 1 Hold a metre ruler vertically, with the zero

level with the top of your partners hand.

2 Without warning, let go of the ruler.

Your partner must catch it as quickly as

possible.

3 Note the reading of the ruler (in centimetres)

level with the top of your partners open hand.

4 Have two trial runs and then record the next

three runs.

Fig 1.3.9

Prac 1Unit 1.3

Fig 1.3.10Measuring reaction time

good accuracypoor precision

good precisionpoor accuracy

good accuracygood precision

bad news

ruler

have yourfingerslevel withzero the ruler

hasdropped22 cm

>>

Experiment Distance ruler dropped Average ruler drop Average reaction time

(cm) (cm) (s)

No distractions

No warnings

With countdown

With distractions


28/259

20

>>>

5 Calculate the reaction time by dividing the average ruler

drop by 490. Now square root ( ) your answer. The

final answer is the time in seconds that your partner

took to react.

6 Repeat the experiment, but this time count down(54321) before dropping the ruler.

7 Try again, but this time get another student to distract

your partner, by talking to them, tickling them, etc.

Questions

1 Identifythe degree of accuracy of a normal stopwatch

2 Contrastthe reaction time with the accuracy of a

stopwatch. 3 Identifyfactors that affected the reaction time in this

experiment.

4 Outlinefactors that affect your reaction time in everyd

life.

Repeated measurements

AimTo examine why taking a number ofmeasurements is important

Equipment

Measuring tape, thermometer, stopwatch

Method

1 Measure each of the following as carefully as you can.

Have each member of your group do the same:

the length of the laboratory

the temperature of tap water

the number of heartbeats in a minute.

the time it takes for a pen to drop 2 m to the floor.

the time it takes

for a flat piece

of A4 paper to

flutter from a

height of 2 m tothe floor.

2 Calculate the

average for each

measurement.

3 Record this average

with a error.

Introduction to the

pendulumA pendulumis a mass (called a bob) attached to

a rod, chain or rope, which swings back and forth

repeatedly.

The periodof a pendulum is the time it takes to

complete one entire swing, back and forth.

A grandfather clock has a pendulum that keeps the clock

on time. Many machines have arms and parts that also act

like pendulums. Their timing is important and scientists must

know what affects the period so that these machines and

devices stay accurate.

Important variables that could logically affect the period

are: the length of the string

the mass of the bob (sometimes incorrectly called its

weight)

the angle of the bob from vertical at the start.

In this experiment you will see if the mass has any effect

on period.

Prac 3Unit 1.3

Fig 1.3.11 Pendulums are everywhere!


Prac 2Unit 1.3

Chaosatplay!Haveyouevernoticedthatprofesstennisplayersarealwaysontheirwhentheyareabouttoreceivease

Theunstablenatureoftheirfootingsequickentheir response, makingthem

likelytoreturntheball.Accuratemeasurementsofheartbeatsthattheyareroughlythesame,butallslightlydifferent.Theslightlyunsbeathelpskeepourheartonitstoe

It canthenrespondtoanysuddenneeincreasedbloodsupplywhenweexerThisisthescientifictheorycalled

chaosatwork.


29/259

Fig 1.3.14A practical pendulum

1 period

stringretort stand

boss headand clamp

bob

Fig 1.3.12 Is the mass an important variable?

AimTo investigate the effect of changing the mass of thebob on a pendulum

Equipment

Materials to construct a pendulum, stopwatch or appropriate

data-logging equipment, clock or watch, protractor (optional)

6 Plot a graph of period versus mass, with mass on the

horizontal axis.

Mass Time for Average time for Period 10 swings (s) 10 swings (s) (s)

Mass 1

Mass 2

Period(s)

Mass (g)0

Fig 1.3.13Use these axis markings

Method

1 Before you start you need to decide:

what masses should be used (50 g masses, paper

clips, metal washers?)

what length your pendulum is to be what angle your pendulum needs to be swung from

each time and a method of making sure it is always

the same.

2 Construct a results table or spreadsheet like the following:

3 Tie one mass on the end of the pendulum, measure the

length of the pendulum and hold the mass out to the

angle you have decided on.

4 Let go and time ten complete swings.

5 Put your results in the table, add another mass and

repeat. Keep adding until you have tested five different

masses.

7 Draw a line or curve of best fit for the points.

Questions

1 Describevariables that you controlled in this experime

2 Identifythe dependent and independent variables.

3 Describehow you made sure the angle was always

the same.

4 Explainwhy ten periods were measured rather than

just one.

5 Identifyother variables that could affect the period.

(Think about the bob and the string itself.)


30/259

22

>>>UNITUNIT

1.41.4Scientists follow conventions or rules

when they present their data, graphs and

reports. This is so that other scientists know

exactly what was observed, and how the

information was interpreted. It also allows

them to repeat the experiment if necessary.

As a scientist you should follow these

conventions too.

context

What do you write in a report?When you write a report you need to include the

following:

a heading, the date of the experimental work and a

list of partners who assisted you

your aimstatement of what you intended to do or

find out

a hypothesis(optional)prediction or educated

guess about what you thought might be found

out

a list of equipment ormaterialsused

your methodexplanation of what was done in theexperiment, including the quantities used.

A diagram can be useful here too

your results andobservationscomplete list of

measurements and observations that were taken,

preferably displayed in a table

a discussion oranalysis, in which you discuss

what you think your results show. This also

includes what you have found about the

experiment from secondary sources. It could

include graphs, ideas for further experiments, a

description of problems encountered and what

was done to overcome them

a conclusionsummary of what was found out in

the experiment. It must be short and must relate to

the aim.

A report sometimes ends with a list of all resources

used in gathering information about the experiment.

This is called abibliography.

Organising results

Data is the word used for a lot of measurements

or observations. Data is usually placed in a table

(tabulated), sometimes as a computer spreadsheet o

database. This makes any patterns that may exist m

obvious. Headings and units should be at the top of

each column.

Drawing line graphs

Patterns become even more obvious when data isplotted as a line graph. Line graphs can be used to

predict patterns and measurements that were never

actually taken in the experiment. Pie charts, bar

graphs and histograms are useful but cannot be used

to predict missing measurements.

When drawing a line graph you must always

include:

a heading, explaining what the graph is about

ruled vertical and horizontal axes

labelsand unitson the axes

regular markings for the scale along the axes

all your points clearly marked on the graphitself.

The independent variable is placed on the

the horizontal axis. The independent variableis

the variable you have chosen to change in your

experiment. You decide how large it should be and

how much it should change by. The number of

days after birth is the independent variable in

Figure 1.4.1.

The dependent variableis placed on

the vertical axis. This is the variable that

depends upon the independent variable and

is measured throughout the experiment.

In Figure 1.4.1, the length of the mouse is

the dependent variable.

All experiments include errors, and connecting u

the points in a dot-to-dot manner suggests that there

is noerror. It is more sensible to draw a straight lin

or smooth curveapproximately through the centre

Pracp. 2


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Graphs showing common relationships

As xgets biggygets bigger bthen levels out

As xgets biggerygets much bigger(ymore than doublesif xdoubles).

Could be describedas a linear relationship(ydoubles if xdoubles).

y

x

y

x

y

Fig

A line of best fit is notdot-to-dot

0 1 2 3 4 5 6 7 8 9 10

70

65

60

55

50

45

40

35

30

25

20

15

10

5

0

Lengthofmouse(mm)

Daysafter birth

independent variableyou choose how big

dependentvariable

changesnaturally

line of best fit

Length of baby mouse as it grows

Fig 1.4.1your points: this is called the line of best fitor curv

of best fit. Patterns and results can then be predicte

You can predict extra results by continuing the shap

of the line or curve. This is called

extrapolation. In Figure 1.4.2 the

curve has been extrapolated to allow

us to predict that the temperatureafter 15 minutes would be 22C.

Describing patterns

Graphs of straight lines or smooth curves indicate

that there is a pattern, rule or relationship between

the variables that you tested. Some ways of describi

these rules are shown in Figure 1.4.3.

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

100

90

80

70

60

50

40

30

20

10

0

Temperature(C)

Time (minutes)

curve of best fit

extrapolation (logicalextension of graph)

The cooling curve of water

Fig 1.4.2 Line graphs can be used to predict missingvalues. For example, the temperature was 32Cat 8 minutes, and took 41/2minutes to reach48C. What do you predict the temperature tobe at 15 minutes?

Prac 2p. 26 Pracp. 2

Using and converting metric units

Scientific measurements are

based on the metric system.

Length is measured in metres

(m), mass in grams (g) and

volume in litres (L). Other units,

such as newtons (N) for weight

and force, and joules (J) for

energy, depend on these units.

Sometimes measurements

are too big or too small to besensibly measured with these

units. Other units have been

developed from them using a

series of prefixes. The prefixes

you have probably already met

are centi, milli and kilo in units

such as centimetre or cm (100

are required to make up a metre),

Thesizeofa

Asmellmightbeinvi

actuallyparticlesoft

thatmadethesmell,

inthethinlayerof

thenose.Afrighteni

consideringwhatweday!Atypicalsmell

of only760ngor76

ofagram.Thisisa

massofthesmalles

parasitewasp)but1

heavierthanthelig

Thismeansthatw

possiblysmellavi

commonc

Worksheet 1.3 Graphing skills


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24

>>>

1.4

UNIT

[ Questions ]

10 Metric prefixes are not usually used for time. Stateth

following metric time units in seconds (s):

a 1 kilosecond or 1 ks

b 1 centiminute or 1 cmin

c 1 kiloday or 1 kd

d 1 megasecond or 1 Ms.

Analyse

11 Sam measured the times it took for a feather and a

stone to fall from different heights so that she could

compare them. She obtained the graph shown in

Figure 1.4.4.

Checkpoint

1 Definethe following terms:

a convention d relationship

b hypothesis e bibliography.

c line of best fit

2 Describethe type of information found in the discussion

section of an experiment.

3 Listall the details that must be included on a graph.

4 Proposethe correct axis for the independent variable

on a graph.

5 Explainthe usefulness of the metric system in science.

6 Describehow a line of best fit is obtained when

drawing a graph.

7 Proposetwo places where diagrams would be useful in

an experimental report.

8 Explainwhy scientists use line graphs more often than

pie charts and bar graphs.

Think

9 Modifythe following values to make the conversions

shown:

a 5 ML into litres

b 375 mL into litres

c 500 000 mm into metres

d 6 000 000 000 nm into metres.

millilitre or mL (one thousand make up one litre) and

kilogram or kg (equal to a thousand grams).

You have probably never heard of the

other prefixes, although all of them

are used for very small or very large

quantities.

Prefix symbol Name of prefix Size Decimal notation Example

G Giga one billion 1 000 000 000 GL

M Mega one million 1 000 000 ML

d deci one-tenth 1/10 = 0.1 dL micro one-millionth 1/1 000 000 = 0.000 001 m

n nano one-billionth 1/1 000 000 000 = 0.000 000 001 nm

Prac 4p. 27

0 1 2 3 4 5

2.6

2.4

2.2

2.0

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0

Timetodrop(s)

Height of drop (m)

stone

feather

Drop times

Fig 1.4.4Sams graph

Scientific conventionsScientific conventions

Worksheet 1.4 Body mass index


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0 1 2 3 4 5 6 7 8 9 10

Mass(kg)

Time (min)

60

50

40

30

20

10

0

Fig 1.4.5

c Constructa correct version of the graph.

0 1 2 3 4 5 6 7 8 9 10

Temperature

Seconds

100

90

80

70

60

50

21.3

15.5

9.1

7.8

3.20

Fig 1.4.6


1 Researchand presentinformation about the followin

features of the metric system. Include a bibliography the information presented.

a Outlinewhere, when and why the metric system

was developed.

b Describehow the length of a metre was originally

determined.

c Use an example to explainwhat a measurement

standard is.

2 Carry out research to identifythe metric units used fo

the following measurements:

a air pressure

b force

c energy

d electrical current

e electrical voltage.

3 Describewhere the following units are used:

a megatonne (Mt)

b decibel (dB)

c gigabyte (Gb).

13 a Identifyfive mistakes in the plotting of the graph in

Figure 1.4.6.

b Decide whether the independent variable is plotted on

the correct axis. Justifyyour answer.

a Proposean aim for Sams experiment.

b Constructa table of results for the experiment.

c Use the graph to identifythe drop time for the feather

and stone from these heights:

i 1.5 m

ii 2.5 m

iii3500 mm.

d Extrapolatethe height that the feather and the stone

were dropped from, given the following times.

i 0.5 s

ii 1.2 s

iii1.9 s.

e Extrapolatethe graph to find the values of the

following measurements:

i time taken to drop the feather 5 m

ii time taken to drop the stone 5 m

iiithe position of the feather after 2.5 s.

f Draw conclusions from the experiment.

Skills

12 a ExamineFigure 1.4.5 and assesswhether all the data

for the points plotted is reliable.

b Copy the graph onto graph paper and constructa line

of best fit.

c Proposea title for the graph.


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UN

IT

Prac 1Unit 1.4

How does length affect a pendulum?

AimTo investigate if the length of a pendulumaffects its period

Equipment


data-logging equipment, clock or watch, protractor (optional)

Method

1 You need to keep constant the mass and the angle from

which the pendulum is swung. Decide what values you

will use.

2 Decide on the lengths that you will test. At least five

different lengths should be tested.

3 You need to repeat measurements for the time taken for

ten complete swings. Decide how many times you will

repeat each experiment.

4 Construct a table or spreadsheet for the measurements

you take.

5 Perform the experiment, recording the time taken.

6 Calculate the average time for ten swings and for one

swing (the period).

7 Plot a graph of period versus length.

Extension

One aim of a scientist when analysing results is to try and

get a straight line when plotting graphs. If you didnt get astraight line then try this.

8 Make another

column in your

table. Use a

calculator to take

the square root

( ) of the lengths

you used and enter

these into the new

column.

9 Plot a new graph

of period versus

square root length.

Questions

1 Discussany precautions taken in the experiment to

reduce errors.

2 Identifythe controlled variables.

3 Identifythe independent and dependent variables.

4 Use the shape of the curve obtained in the graph

to outlineany relationship evident between the

dependent and independent variables.

5 Draw conclusions from the data obtained.

Period(s)

Length

Fig 1.4.7 Plotting period

against squareroot length

Prac 2Unit 1.4

Does the angle matter?

AimTo investigate the effect of angle on theperiod of a pendulum

Equipment


data-logging equipment, protractor

Method 1 Bigger angles could mean longer periods, shorter periods

or no change in period. Construct your hypothesis about

the effect of angle on period.

2 Design an experiment to test your hypothesis.

3 Construct a graph showing the relationship between

period and angle of pendulum swing.

Questions

1 Outlinehow you controlled

variables that you did not

want to test.

2 Does the shape of the graph

support your hypothesis?

Justifyyour answer.

3 Proposefurther questions

that arise from this

experiment.

Scientific conventionsScientific conventions

FoucaultspenduApendulumlooksas

neverchangesdirectionisbecausemostpenduareshortandall pendueventuallystopduetoresistance.Asapendu

movesbackandforth, thisslowlyspinningunderIfthependulumkeptgoiwouldseeit slowlychadirection.After24houwouldreturntoitsorigorientation.ApendulumdoesthisiscalledFouca

pendulum.


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Prac 3Unit 1.4

Complex pendulums

AimTo investigate different pendulums

Equipment

Materials to construct a pendulum, stopwatch

Method 1 Construct one of the pendulums shown.

2 Identify two variables that you think could

affect the period.

3 Design two experiments that test those

variables.

4 Report on your findings, including a graph for

each experiment.

DYO

bridge

pendulum

chain

pendulum

double

pendulum

Fig 1.4.8Other pendulums to try

Prac 4Unit 1.4

3 Describethe shape of all graphs you plotted.

4 From the shape of the graphs describeany patterns in

the relationships between variables.

5 Use the information obtained from graphs to draw

conclusions for both experiments.

Drop time

AimTo investigate the variables in the droptime of a parachute.

Equipment

Lightweight materials (such as tissue paper, plastic sheet

(garbage bags), newspaper), fine cotton, hole punch, sticky

tape, small masses (plasticine or paper clips are ideal),

electronic balance, stopwatch

Method

1 Brainstorm a list of variables that could affect the drop

time of a parachute.

2 Select the two variables that your group

thinks will have the most effect. 3 Design two experiments that will test your

two variables. Remember to keep everything

else the same.

4 When constructing your chutes, reinforce the

string holes with patches of sticky tape.

5 Drop your chutes from a height of at least

2 m.

6 Make repeated measurements of the time the

chutes take to hit the ground, recording the

measurements in a table or spreadsheet.

7 Write a report of your research, including a

line graph for each experiment.

Questions

1 Identifythe variables that may be important

in this experiment.

2 Explainwhy you chose the variables you

tested and not others.

Fig 1.4.9 Testing parachutes

light materials,eg paper, plastic

sticky tapereinforcing

mass

stopwatch

chute

2 mor more


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28

>>>

Chapter review

[ Summary questions ] 1 Contrastthe work of scientists with that of other workers.

2 Identifytwo examples of each of the following types of

observations:

a qualitative

b quantitative

c visual

d made with the sense

of touch only

3 Contrasteach of the following terms:

a an experiment and research

b a qualitative and a quantitative observation

c an aim and a hypothesis

d an error and a mistake.

4 Draw diagrams to explainthe following types of errors:

a parallax errors b reading errors.

5 Use an example to contrasta dependent with an

independent variable.

6 Use an example to explainhow human reflex can add

errors to an experiment.

7 In order, listthe features normally included in an

experimental report.

[ Thinking questions ] 8 Sarah wrote the length of an insect as 2.1 0.1 cm.

Statethe biggest and the smallest length of the insect.

9 Recordthe following measurements correctly showing

the errors.

a The time a stone took to drop to the ground was

measured by Kim as 2.5 seconds, give or take half a

second.

b Jess measured the temperature that salt water boiled

at as somewhere between 102C and 108C.

10 Calculatethe average value for the following

measurements.

a 87 mL, 90 mL, 86 mL and 93 mL

b 115 g, 123 g and 125 g.

11 Proposea reason for all scientists using the same units

for their measurements.

12 One of the most powerful cars built in Australia was the

285 kW HSV Clubsports R8. Calculatethe cars power

in watts.

13 The World Health Organization recommends that people

should eat 10.9 MJ of food each day. On average in

0 1 2 3 4 5

Soundintensity

Distance (m)

70

60

50

40

30

20

10

0

Fig 1.5.1

16 Copy Figure 1.5.1 into your workbook and:

a identifythe independent variable

b identifythe variable that changed naturally

c identifywhat is missing from the axes

d constructa table of results for the experiment

e constructa line or curve of best fit through the data

f predictthe sound intensities for the following distani 1.5 m

ii 2.8 m

g predictthe distances for the following sound intensi

i 45

ii 32

Australia we eat 13 500 kJ. Many claim that Australian

eat more than the recommended allowance. Justifyth

statement.

14 Recommendappropriate metric units for the following

measurements:

a the length of a sugar ant

b the amount of water in Botany Bay

c the distance from here to the next galaxy.

15 Design a controlled experiment that would test the

hypothesis that adding salt to water causes an increas

the boiling point of water.

[ Interpreting questions ]

e made with the sense

of hearing only

f made with the sense

of taste or smell only.

iii350 cm

iv6000 mm

v 0 m.

iii20

iv 55.

Worksheet 1.5 Sci skills crossword

Worksheet 1.6 Sci-words


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>>>

By the end of this chapter you should beable to:

distinguish between an element, acompound and a mixture

distinguish between an atom, a moleculeand a lattice

recall the symbols of some elements

write the formulae for some simplecompounds

identify whether a change in a substanceis due to a physical or a chemical change

write simple word equations to describea chemical change

classify chemical reactions into one of

four types identify ways in which chemical reactions

can be sped up.

1 Do you think the symbol Fe stands forferret, ferocious or iron?

2 Which do you think is the symbol forchlorine? C, Ca, Cl or Co?

3 Are you making a new substance whenyou add water to cordial?

4 List what is produced when paper isburnt.

5 Why are vegetables stored in therefrigerator?

6 Which do you think will relieve aheadache more quickly: a whole aspirintablet or the same tablet crushed?

7 You can easily see an atom with anordinary microscope. True or false?

22

AtomsAtomsKey focus areas:

The nature and practice of scienceThe history of science

>>>

>>>


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30

>>>UNITUNIT

2.12.1

In the fourth century BC, Greek philosophers

thought that everything was made from

four basic ingredients: earth, air, fire and

water. We now know that all matter is made

from basic ingredients. These are not the

ingredients of the ancients, however, but

elementsaround one hundred of them. These

elements make up the planets and the stars andevery substance that we see, breathe, drink and

use. They even make up our bodies.

context

ElementsAn elementis an absolutely pure substance that

cannot be broken down into other substances. If you

were asked to name some pure substances, you might

mention substances such as plastic, paper, air and

sugarhowever, none of these are elements! The

reasonthey can all be broken down into simpler

substances. There are several possible ways to break

down a substance, such as burning or using acids or

other chemicals. When plastic, wood or paper are

burnt, they break down to reveal the carbon within

them. Carbon is an element, as it cannot be broken

down any further.

Some other elements are

aluminium, copper, oxygen,

sodium and chlorine.

The periodic table

(to be studied indetail next year) is a

complete list of all

the known elements.

There are 92 naturally

occurring elements, most of

which were discovered in

the last 400 years, and over

20 synthetic elements.

Teacher demonstration

Your teacher may conduct a demonstration in a fume

cupboard, showing how sugar may be broken down by

concentrated sulfuric acid. The acid breaks the sugar

down into

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