PREFACE Browsing through hardware stores can be fun, interesting, and informative. Hardware stores sell tools and supplies used by mechanics, plumbers, carpenters, homeowners, hobbyists, and do-it-yourselfers. When you have-and know how to use-tools, you can demolish, disassemble, fix, or build just about anything. I was very lucky as a youngster. My grandfather, Louis Helfand, was an expert mechanic and woodworker. He came to live in my parent's house when I was about 10 years old. While he lived with us, he showed me the correct way to use and care for tools. It was through his patience, and his ability to explain the functions of tools, that I became interested in both the tools and the scientific principles that allow them to work. Grandpa took tools very seriously. He praised the ones that were well made and cursed the ones that weren't. In other words, he told it like it was. When I walk through a hard- ware store today, I remember Grandpa pointing out the tools, both good and bad. Sometimes his comments made me laugh so hard that my stomach hurt. Hardware stores still hold a fascination for me. There always seem to be new, strange, nifty, cool, wonderful machines, and tools. I can look at them, touch them, examine them, and even buy them. This book is written as a guidebook to help you learn the scientific principles that make some of the tools dis-played in a hardware store work. I hope that after read-ing this book you will enjoy browsing through hardware stores as much as I do. Who knows? One day we might even meet in one. His comments made me laugh so hard that my stomach hurt. Hardware stores still hold a fascination for me. There always seem to be new, strange, nifty, cool, wonderful machines, and tools. I can look at them, touch them, examine them, and even buy them. This book is written as a guidebook to help you learn the scientific principles that make some of the tools dis-played in a hardware store work. I hope that after read-ing this book you will enjoy browsing through hardware stores as much as I do. Who knows? One day we might even meet in one. * * * * * A Quick Note to Parents and Educators Physics Lab in a Housewares Store, a companion volume in this series, demonstrates many of the same principles as this book. That has been done with intent. Many of the students who will be attracted to one of the titles will probably not be attracted to the other, due to traditional gender preferences. Those that are attracted to both will have the added pleasure of finding out that a workshop and a kitchen have many things in common, and that tools found in one might actually be substituted for those commonly used in the other."