Back Of The Envelope Physics

From an award-winning teacher, “a delightful and instructive accessory to an introductory physics course” (Physics World). 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—a winner of two awards from the American Association of Physics Teachers—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, this book provides a rich source of material for teachers and anyone interested in the physics of everyday life. “This is a book that will help make the study of physics fun and relevant.” —Mark P. Silverman, author of Waves and Grains: Reflections on Light and Learning

The essential primer for physics students who want to build their physical intuition Presented in A. Zee's incomparably engaging style, this book introduces physics students to the practice of using physical reasoning and judicious guesses to get at the crux of a problem. An essential primer for advanced undergraduates and beyond, Fly by Night Physics reveals the simple and effective techniques that researchers use to think through a problem to its solution—or failing that, to smartly guess the answer—before starting any calculations. In typical physics classrooms, students seek to master an enormous toolbox of mathematical methods, which are necessary to do the precise calculations used in physics. Consequently, students often develop the unfortunate impression that physics consists of well-defined problems that can be solved with tightly reasoned and logical steps. Idealized textbook exercises and homework problems reinforce this erroneous impression. As a result, even the best students can find themselves completely unprepared for the challenges of doing actual research. In reality, physics is replete with back of the envelope estimates, order of magnitude guesses, and fly by night leaps of logic. Including exciting problems related to cutting-edge topics in physics, from Hawking radiation to gravity waves, this indispensable book will help students more deeply understand the equations they have learned and develop the confidence to start flying by night to arrive at the answers they seek. For instructors, a solutions manual is available upon request.

Engineers need to acquire “Back-of-the-Envelope” survival skills to obtain rough quantitative answers to real-world problems, particularly when working on projects with enormous complexity and very limited resources. In the case studies treated in this book, we show step-by-step examples of the physical arguments and the resulting calculations obtained using the quick-fire method. We also demonstrate the estimation improvements that can be obtained through the use of more detailed physics-based Back-of-the-Envelope engineering models. These different methods are used to obtain the solutions to a number of design and performance estimation problems arising from two of the most complex real-world engineering projects: the Space Shuttle and the Hubble Space Telescope satellite.

Dimensional and order-of-magnitude estimates are practiced by almost everybody but taught almost nowhere. When physics students engage in their first theoretical research project, they soon learn that exactly solvable problems belong only to textbooks, that numerical models are long and resource consuming, and that 'something else' is needed to quickly gain insight into the system they are going to study. Qualitative methods are this 'something else', but typically, students have never heard of them before.The aim of this book is to teach the craft of qualitative analysis using a set of problems, some with solutions and some without, in advanced undergraduate and beginning graduate Quantum Mechanics. Examples include a dimensional analysis solution for the spectrum of a quartic oscillator, simple WKB formulas for the matrix elements of a coordinate in a gravitational well, and a three-line-long estimate for the ionization energy of atoms uniformly valid across the whole periodic table. The pièce de résistance in the collection is a series of dimensional analysis questions in Integrable Nonlinear Partial Differential Equations with no dimensions existing a priori. Solved problems include the relationship between the size and the speed of solitons of the Korteweg-de Vries equation and an expression for the oscillation period of a Nonlinear Schrödinger breather as a function of its width.A new theme that appears in the second edition are the rare and exotic methods in elementary quantum mechanics. The new chapter covers quantum-mechanical supersymmetry, power index method, scale invariance, self-similarity, and circle inversion.

Provides an exploration of the science behind the powers of popular comic superheroes revealing the real physics at work in comic books.

Blending simple physics with anecdotes from the world of rugby, this informative reference demonstrates how to improve rugby techniques. Tackling, passing, running, and kicking are analyzed from a scientific perspective, incorporating Newton’s Laws, and then discussed in the wider context of the game. This valuable guide will not only instruct but also entertain sports-oriented students of all levels.

‘Another terrific book by Rob Eastaway’ SIMON SINGH ‘A delightfully accessible guide to how to play with numbers’ HANNAH FRY

Guesstimation is a book that unlocks the power of approximation--it's popular mathematics rounded to the nearest power of ten! The ability to estimate is an important skill in daily life. More and more leading businesses today use estimation questions in interviews to test applicants' abilities to think on their feet. Guesstimation enables anyone with basic math and science skills to estimate virtually anything--quickly--using plausible assumptions and elementary arithmetic. Lawrence Weinstein and John Adam present an eclectic array of estimation problems that range from devilishly simple to quite sophisticated and from serious real-world concerns to downright silly ones. How long would it take a running faucet to fill the inverted dome of the Capitol? What is the total length of all the pickles consumed in the US in one year? What are the relative merits of internal-combustion and electric cars, of coal and nuclear energy? The problems are marvelously diverse, yet the skills to solve them are the same. The authors show how easy it is to derive useful ballpark estimates by breaking complex problems into simpler, more manageable ones--and how there can be many paths to the right answer. The book is written in a question-and-answer format with lots of hints along the way. It includes a handy appendix summarizing the few formulas and basic science concepts needed, and its small size and French-fold design make it conveniently portable. Illustrated with humorous pen-and-ink sketches, Guesstimation will delight popular-math enthusiasts and is ideal for the classroom.