← Physics C: Mechanics syllabus

United StatesPhysics C: Mechanics

Unit 4: Linear Momentum

4 dot points across 4 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How does an impulse change an object's momentum, and how do we compute impulse as the integral of force over time and as the area under a force-time graph?

Topic 4.2 Change in Momentum and Impulse: define impulse as the integral of force over time, relate it to the change in momentum, and interpret the force-time graph and the average force.
A focused answer to AP Physics C: Mechanics Topic 4.2, covering impulse as the time integral of force, the impulse-momentum theorem, impulse as the area under a force-time graph, the role of average force and contact time, and applications to collisions and cushioning, with calculus-based worked examples.
11 min answer →

How do elastic, inelastic and perfectly inelastic collisions differ, and how do we use momentum and energy conservation to analyze each?

Topic 4.4 Collisions: classify collisions as elastic, inelastic or perfectly inelastic, apply momentum conservation to all and kinetic-energy conservation to elastic collisions, in one and two dimensions.
A focused answer to AP Physics C: Mechanics Topic 4.4, covering the classification of collisions, momentum conservation in all collisions, kinetic-energy conservation only in elastic collisions, the combined-mass result for perfectly inelastic collisions, two-dimensional collisions by components, and the elastic one-dimensional relative-velocity result, with worked examples.
11 min answer →

When is the total momentum of a system conserved, and how do we use conservation of momentum to analyze interactions such as explosions and recoil?

Topic 4.3 Conservation of Linear Momentum: state that the total momentum of an isolated system is conserved, and apply it to recoil, explosions and interactions in one and two dimensions.
A focused answer to AP Physics C: Mechanics Topic 4.3, covering the condition for momentum conservation (zero net external force), why internal forces cannot change total momentum, and applying conservation to recoil, explosions and two-dimensional interactions by components, with worked examples.
11 min answer →

What is linear momentum as a vector, and how does it relate to a system's mass and velocity and to Newton's second law?

Topic 4.1 Linear Momentum: define linear momentum as the product of mass and velocity, treat it as a vector, and relate the net force to its rate of change.
A focused answer to AP Physics C: Mechanics Topic 4.1, covering linear momentum as a vector equal to mass times velocity, the momentum of a system as the sum of its parts, the relation between momentum and the center-of-mass velocity, and Newton's second law as the rate of change of momentum, with worked examples.
10 min answer →