A basic, non-mathematical textbook for non-science students in secondary school or college. The book is based on Robert Karplus' many years of research on how beginners think about physics. In the "modeling approach" students explore and test simple analog, working and mathematical models for physical phenomena. The models provide a clear, understandable transition to the key principles and theories of physics. The book begins with the basic concepts of relative motion, reference frames, interaction, systems, and a descriptive overview of energy transfer. Subsequent chapters develop the...