This book is a great addition to any mechanics enthusiast's collection. Written by A.J. Sadler, the 2nd edition of "Understanding Mechanics" is a comprehensive guide that covers the principles of mechanics and how they apply to everyday objects. The book is in excellent shape and has been well-maintained. It is a great value for anyone looking to expand their knowledge of mechanics. With free shipping, this is a great opportunity to add a valuable resource to your library.