Back-of-the-Envelope Physics - 9780801872631

Physicists use back-of-the-envelope estimates to check whether or not an idea could possibly be right. In many cases, the approximate solution is all that is needed. This compilation of 101 examples of back-of-the-envelope calculations celebrates a quantitative approach to solving physics problems. Drawing on a lifetime of physics research and nearly three decades as the editor of The Physics Teacher, Clifford Swartz provides simple, approximate solutions to physics problems that span a broad range of topics. What note do you get when you blow across the top of a Coke bottle? Could you lose weight on a diet of ice cubes? How can a fakir lie on a bed of nails without getting hurt? Does draining water in the northern hemisphere really swirl in a different direction than its counterpart below the equator? In each case, only a few lines of arithmetic and a few natural constants solve a problem to within a few percent. Covering such subjects as astronomy, magnetism, optics, sound, heat, mechanics, waves, and electricity, the book provides a rich source of material for teachers and anyone interested in the physics of everyday life. If the physical world is to make sense to students (or even to professional scientists), then it must be understandable on the basis of broadly applicable principles and simple communicable reasoning. Long, dry calculations alone will not do, for they are as devoid of insight as they are impenetrable. Here, however, is a book of wide-ranging and aptly chosen topics--each brief glimpse conveying its (sometimes surprising!) lesson in one page with a short, physically insightful, quantitative argument. This is a book that will help make the study of physics fun and relevant. --Mark P. Silverman, author of A Universe of Atoms ...An Atom in the Universe and Waves and Grains: Reflections on Light and Learning This book is a treasure trove of fascinating calculations covering a wide range of physical principles, distance scales, and numerical orders of magnitude. Everyone with some curiosity about the natural world, from novice students to seasoned veterans, will find a variety of interesting cases in this wonderful collection. --Gregory N. Derry, author of What Science Is and How It Works The book is fun to read. I look forward to mining it for examples with which to spice up my lectures. --Don S. Lemons, author of Introduction to Stochastic Processes in Physics