Challenging Concepts in Physics

Need help with difficult concepts? Advanced high school or starting university level? This MOOC at EdX should help. It is done by experienced teachers and includes:
 Acceleration
 Force Diagrams
 Momentum
 Rotational Motion
 Angular Momentum
 Standing Waves
 Conservation of Charge & Energy in Circuits
 Electrostatic Fields
 Gravitational and Electric Potentials
 Electromagnetic Induction
 Thermodynamics
 Pressure, Force & Flow in Fluids
 Diffraction & Interference
 Atomic Transitions

The course uses short instructional videos, on-screen simulations, interactive graphs, and practice problems.
Sounds really useful.