cK-12 Basic Physics – Second Edition – A good book with simplified writing, solved examples and practice problems.
cK-12 People's Physics Book Version 3 (with Videos) – A textbook with more of an emphasis on conceptual understandings and less difficult math. LOTS of practice problems, and videos, of course!
cK-12 Physics Concepts – Intermediate – A stripped down, “Cliffs Notes” version of a physics textbook appropriate for the AP level. I like this text for review of concepts I’ve already learned but want a quick refresher. It also includes practice problems and links to explanatory YouTube videos.
cK-12 Physics Intermediate – A more in-depth, AP level textbook with deep explanations, diagrams, and practice problems.
HyperPhysics – An online-only text with focused, straightforward explanations, clear diagrams and some interactivity.
OpenStax College Physics – A complete, college-level text loaded with diagrams and formulas. Very high quality, but very complex and bit more difficult to read.
The Physics Classroom – Simpler to understand than all of the other textbooks with an emphasis on mechanics and containing cartoon-style diagrams and an explanation or demonstration video at the end of each lesson.
The Physics Hypertextbook – A complete textbook that’s mobile-friendly with a heavier emphasis on the derivations of equations using algebra and calculus. Each section has practice problems and explanations, but some sections are incomplete.
TeachEngineering: Physics – Physics curricular units, lessons and activities from an engineering perspective.
Teaching Advanced Physics – Aimed more at teachers, this textbook is straightforward with numerous diagrams and lots of practice problems and labs in Word format.