Introduction to and Andy Ruina and Rudra Pratap

12 Chapter 0. Preface Preface
namics or more advanced Multi-object Dynamics.
Organization and formatting
Each subject is covered in various ways.
Every section starts with descriptive text and short examples motivating
and describing the theory;
More detailed explanations of the theory are in boxes interspersed in
the text. For example, one box explains the common derivation of angular
momentum balance from * F D m * a (page 974), one explains the
genius of the wheel (page 208), and another connects * ! based kinematics
to Oe r and Oe based kinematics (page 856);
Sample problems (marked with a gray border) at the end of each section
show how to do homework-like calculations. These set an example
by their consistent use of free-body diagrams, systematic application
of basic principles, vector notation, units, and checks against both intuition
and special cases;
Homework problems at the end of each chapter give students a chance
to practice mechanics calculations. The first problems for each section
build a student’s confidence with the basic ideas. The problems are
ranked in approximate order of difficulty, with theoretical problems
coming later. Problems marked with a * have an answer at the back
of the book;
Reference tables on the inside covers and end pages concisely summarize
much of the content in the book. These tables can save students
the time of hunting for formulas and definitions.
Notation
Clear vector notation helps students do problems. One common class of
student errors comes from copying a textbook’s printed bold vector F the
same way as a plain-text scalar F . We reduce this error by use a redundant
vector notation, a bold and harpooned F * .
As for all authors and teachers concerned with motion in two and three
dimensions we have struggled with the tradeoffs between a precise notation
and a simple notation. Perfectly precise notations are complex and intimidating.
Simple notations are ambiguous and hide key information. Our attempt
at clarity without too-much clutter is summarized in the box on page 40.
1 For example, we use angular
momentum balance (appropriately
expressed) with respect to any possiblyaccelerating
point, not just points
selected from an arcane list.
Relation to other mechanics books
The bulk of the content of this book can be found in other places including
freshman physics texts, other engineering texts, and hundreds of classics.
Nonetheless this book is in some ways different in organization and approach.
It also uses some important but not well-enough known concepts 1 .
Mastery of freshman physics (e.g., from Halliday, Resnick & Walker, Tipler,