Principles of Physics is a textbook for a one year algebra-based introduction physics course. The book is intended for students in the life sciences, the premedical curriculum, the earth and environmental sciences, and the liberal arts. Since for many students this is their first encounter with physics, I introduce new concepts by qualitative and intuitive discussions whenever possible. And to motivate students and to maintain their enthusiasm, I have drawn on examples from sports, biology, medicine, and everyday life, chosen to match the background and special interests of the students.