AP Physics 1 Unit 7: Oscillations Practice Test
AP Physics 1 Unit 7 Oscillations — simple harmonic motion, period, frequency, amplitude, and SHM energy graphs. AP-style MCQ and FRQ oscillation practice.
Simple Harmonic Motion in AP Physics 1
Unit 7 covers oscillatory motion — the back-and-forth motion of objects like springs and pendulums. Simple harmonic motion (SHM) is one of the most mathematically rich topics in AP Physics 1 and appears in MCQ questions testing graph reading, period calculations, and energy analysis, as well as FRQs requiring qualitative explanations of SHM behavior.
Core Topics in Oscillations
- Conditions for Simple Harmonic Motion — Restoring force proportional to displacement; Hooke's law for springs.
- Period and Frequency — Defining period (T) and frequency (f); understanding their reciprocal relationship.
- Period of a Mass-Spring System — How mass and spring constant affect period; period is independent of amplitude.
- Period of a Pendulum — How length and gravitational field strength affect period; independence from mass and amplitude (for small angles).
- Amplitude and Energy — Total mechanical energy in SHM is proportional to amplitude squared; energy oscillates between kinetic and potential.
- SHM Graphs — Position-time, velocity-time, and acceleration-time graphs; phase relationships between them.
Key AP Skills for Oscillations
Period vs. Frequency — A Common Mistake
Many students confuse period and frequency under exam pressure. Remember: period is the time for one complete cycle (measured in seconds), and frequency is the number of cycles per second (measured in hertz). They are reciprocals, but an AP question that asks how period changes when spring constant doubles is testing whether you know that increasing spring constant decreases period — not increases it.
Amplitude Independence of Period
One of the most frequently tested conceptual points in Unit 7 is that the period of both a spring-mass system and a simple pendulum does not depend on amplitude (for small-angle pendulums). AP MCQ questions often present scenarios where amplitude changes and ask which quantities change — students who incorrectly believe period depends on amplitude will select wrong answers.
Energy Analysis in SHM
AP FRQs may ask you to sketch energy vs. position graphs for an oscillating spring, or to identify the position where kinetic energy is maximum and where potential energy is maximum. At the equilibrium position, all energy is kinetic; at maximum displacement (amplitude), all energy is potential. Connecting these energy transitions to the SHM graph is a high-value AP skill.