5–8% of the AP exam. 7 key topics. 4 common errors analyzed.
Unit 7 (Oscillations) is part of AP Physics 1 (Algebra-Based). Concept-first: understand the physical reasoning before memorizing equations — the four named FRQ types reward explanation over plug-and-chug.
These are the most frequently penalized mistakes on AP exam FRQs and MCQs. Review each before your next practice session.
Swapping the period formulas for springs and pendulums — T_spring = 2π√(m/k) depends on mass and spring constant while T_pendulum = 2π√(L/g) depends on length and gravitational field strength; notably, pendulum period is independent of the bob's mass
Misidentifying when kinetic and potential energy are maximum in SHM — KE is maximum at the equilibrium position (where speed is greatest and displacement is zero) and PE is maximum at the amplitude (where speed is zero and restoring force is greatest)
Incorrect phase relationships: on x-t and v-t graphs, velocity leads position by 90°, and acceleration is always opposite in sign to displacement; students frequently draw these in phase rather than out of phase
Assuming SHM applies to large-amplitude pendulums — the small-angle approximation (sin θ ≈ θ) is required for the standard period formula to hold; large amplitudes produce longer periods than the formula predicts
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