TABLE OF CONTENTS CHAPTER 1 Slow Down 5 CHAPTER 2 What Is Friction 11 CHAPTER 3 Friction in Our World 21 SCIENCE IN ACTION Creating Friction 26 Focus on Friction 28 Glossary 30 To Learn More 31 Index 32
CHAPTER 1 SLOW DOWN Nick straps on his helmet and steps onto his skateboard He pushes off with his foot At first he rolls along quickly But soon he starts to slow down Wheels help people move faster than they could by walking
