Physics C: Mechanics · Unit 4: Systems of Particles and Linear Momentum · 5 min read · Updated 2026-05-11
Systems of Particles and Linear Momentum Overview — AP Physics C: Mechanics
AP Physics C: Mechanics · Unit 4: Systems of Particles and Linear Momentum · 5 min read
1. Unit at a Glance
This unit builds on your knowledge of forces and motion to extend analysis from single particles to multi-particle systems. We first cover how to locate and use the center of mass of a system, then connect force acting over time to momentum change, and finally apply the powerful law of conservation of momentum to a wide range of collision problems. These skills are heavily tested on both multiple-choice and free-response sections of the AP exam.
Common Pitfalls
Why: Momentum is only conserved for isolated systems with zero net external force.
Why: Kinetic energy is only conserved in elastic collisions, not in inelastic collisions.