Using Khan Academy for AP Physics C
Khan Academy isn't officially endorsed by the College Board, and it doesn't map to the AP Physics C syllabus in any formal way. It does cover the core calculus-based physics concepts you need for the exam though, and if you work through the material deliberately, it can be useful. I used it alongside other resources during my prep, and I'll tell you what actually works and where it falls short. The platform has two main physics sections that are relevant: the standard Physics course and the AP Physics C practice module that was added more recently. The standard Physics course is algebra-based and covers kinematics, forces, energy, momentum, and basic circuits. For AP Physics C, you'll need the calculus-based content, which appears in the newer AP Physics C section. The mechanics portion of that module covers kinematics with derivatives and integrals, Newton's laws, work and energy, momentum, rotation, and oscillations. The E&M portion covers electrostatics, circuits, magnetism, and electromagnetic induction. Each topic has video lessons followed by practice exercises. Here is what I ran into that wasn't obvious at first. The Khan Academy exercises are mostly multiple choice and structured numeric problems. They don't give you free-response problems that look like the actual exam. I kept assuming they would, and I wasted time trying to extract FRQ-style thinking from practice sets that were just asking for a number. The workaround was to use the videos and concept checks to build understanding, then go straight to past AP exams for the written problem-solving practice. Khan Academy gets you to the point where you can recognize what the problem is asking. It doesn't train you to write out the solution on paper.
Another thing that trips people up is the difficulty curve. The early problems are straightforward plug-and-chug. Then around the rotation and E&M induction units, the problems start requiring you to set up integrals from scratch. Khan Academy's hint system is decent here, but the step-by-step scaffolding can be slow if you already have some calculus background. I learned to skip ahead to the harder practice sets, attempt them blind, and only then go back and watch the targeted videos for the steps I was missing. This reversed the recommended order, but it saved me maybe three or four hours over a two-week study window. The calculus integration in AP Physics C mechanics is where most students struggle, and Khan Academy handles this inconsistently. The rotation problems are solid. The oscillation and torque sections are clear. The kinematics module sometimes treats calculus as a afterthought, which is a problem because the AP exam expects you to move fluently between graphical, algebraic, and calculus representations of motion. I found myself going to a separate calculus review resource just to bridge that gap. Paul's Online Math Notes covered the relevant calculus applications in about twenty minutes, and that was enough to unblock the Khan Academy problems. The E&M section has its own set of quirks. The Gauss's Law unit is probably the weakest on the platform. The videos explain the concept, but the practice problems don't push you through the kind of symmetric charge distributions the AP exam actually tests. Spherical, cylindrical, and planar symmetry are all fair game, and Khan Academy mostly simple spherical cases. I supplemented that unit with textbook problems from Cutnell and Johnson or the open-access University Physics by OpenSt
