物质科学 初级版 英文版PDF电子书下载

TO THE STUDENT 2

ENERGY 3

Introduction 5

Unit 1 What is Energy? 6

Unit 5 Hot Wires 7

Unit 2 Burning Fuels 11

Unit 3 Fuels from Under the Ground 17

Unit 4 Electricity 22

Unit 5 Solving Energy Problems 33

Unit 6 What Can You Do? 43

Show What You Learned 48

ELECTRICITY 49

Introduction 51

Unit 1 A Special Path 52

Unit 2 On and Off 59

Unit 3 Go with the Flow 65

Unit 4 Electric Light 71

Unit 6 Beware of Bare Wires 83

Unit 7 Watch Out! 89

Show What You Learned 94

SOUND 95

Introduction 97

Unit 1 Making Sounds 98

Unit 2 High Sounds and Low Sounds 105

Unit 3 Sound Travels 113

Unit 4 What Sound Travels Through 119

Unit 5 Sound Changes Direction 127

Unit 6 Using What You Know 135

Show What You Learned 140

MACHINES 141

Introduction 143

Unit 1 Making Work Easy 144

Unit 2 The Inclined Plane 149

Unit 3 The Wedge 156

Unit 4 The Lever 162

Unit 5 The Wheel and Axle 169

Unit 6 The Pulley 176

Unit 7 Using Machines 183

Show What You Learned 186

GLOSSARY 187