The Isaac Newton School of Driving THE ISAAC NEWTON SCHOOL OF DRIVING Physics & Your Car Barry Parker The Johns Hopkins University Press Baltimore & London © 2003 The Johns Hopkins University Press All rights reserved. Published 2003 Printed in the United States of America on acid-free paper 9 8 7 6 5 4 3 2 1 The Johns Hopkins University Press 2715 North Charles Street Baltimore, Maryland 21218-4363 www.press.jhu.edu Library of Congress Cataloging-in-Publication Data Parker, Barry, 1935– The Isaac Newton school of driving : physics and your car / Barry Parker. p. cm. Includes bibliographical references and index. ISBN 0-8018-7417-3 (alk. paper) 1. Mechanics. 2.Elasticity. 3.Motion. 4.Thermodynamics. I.Title: Physics and your car. II.Title. QC125.2.P37 2003 531—dc21 2003047527 A catalog record for this book is available from the British Library. Figures 5–89, 96–101 by Lori Scoffield-Beer To Charles and Olive Vizer Contents Acknowledgments ix CHAPTER 1 Introduction 1 CHAPTER 2 The Open Road: Basic Physics of Driving 12 CHAPTER 3 All Revved Up: The Internal Combustion Engine 32 CHAPTER 4 When Sparks Fly: The Electrical System 62 CHAPTER 5 “Give ‘em a Brake”: Slowing Down 88 CHAPTER 6 Springs and Gears: The Suspension System and the Transmission 111 CHAPTER 7 What a Drag: Aerodynamic Design 137 CHAPTER 8 A Crash Course:The Physics of Collisions 159 CHAPTER 9 Checkered Flags: The Physics of Auto Racing 179 CHAPTER 10 Rush Hour: Traffic and Chaos 199 CHAPTER 11 The Road Ahead: Cars of the Future 219 CHAPTER 12 Epilogue:The Final Flag 239 Bibliography 243 Index 245 Acknowledgments I am grateful to Trevor Lipscombe for his many sugges- tions and help in preparing this volume. Furthermore, I would like to thank Pat Negyesi for his help in obtain- ing photographs. And finally, I thank Alice Calaprice for her careful editing of the manuscript, and the staff of the Johns Hopkins University Press for their assistance in bringing this project to completion. The Isaac Newton School of Driving CHAPTER 1 Introduction New cars, with their sleek, shiny, curved lines, are objects of intrigue, elegance, grace, and beauty. They are exciting, and they can be a lot of fun. The thrill of the first drive in your new car is something you remem- ber for a long time. The science of physics also has a certain beauty and elegance. With a few simple princi- ples and the enormous power of mathematics, you can make amazingly accurate predictions about everything from atomic interactions to the expansion of the uni- verse. And you can also make important predictions about cars. In this book I bring cars and physics together. At first you might not think they have a lot in common, but they do. It’s easy to show that every branch of physics is rep- resented somewhere within an automobile. Mechanics, the branch of physics that deals with motion, is partic- ularly applicable. After all, cars move, and if they are moving they have a certain velocity, and to set them in motion you have to accelerate them. Furthermore, to accelerate them you have to apply a force, and this force comes from a source of energy. Physics is at the basis of all of this. Indeed, two of the main terms that are used in relation to cars are horsepower and torque, both of which are important terms in mechanics.