I'm going to be tutoring HS students (junior and senior) in physics soon enough. I need to have a good, comprehensive source of problems. Any suggestions?
Irodov's Problems in General Physics is excellent but pricey. With about 2000 problems, the book covers I: Mechanics, II: Thermodynamics and Molecular Physics, III: Electrodynamics, IV: Oscillations and Waves, V: Optics, and VI: Atomic and Nuclear Physics. Many of the problems are quite difficult, but there are some easy ones for each section too.