List of useful physics tutorials with LINKS. (K12, High School Physics) Links of some Important K12 Physics Post 1) Elevator Problems in physics – 5 case studies Discussion with Free Body Diagram. Find out the apparent weight of a passenger for different types of movement of the elevator. Nice post. Recommended. 2) How friction helps in walking A nice post with Free Body Diagram explanation.Must Read if you want to know when Friction is a necessary Evil ! 3) Refraction of light and optical density Discusses the concepts of Optical density and how it controls refraction of light. Conceptual post! Go for it. 4) mole versus molecule, avogadro number and molar-mass When we mess up with the concepts of mole and molecule then this is a must read. Will help to solve related numerical problems once you get the concepts clearer, 5) Centripetal Force An awesome posts with a list of ...