Work, energy, and momentum on AP Physics C Mechanics often appear in multi-part FRQs — choose energy when forces are non-constant or path matters; choose momentum for collisions and explosions.

Hub: AP Physics C Mechanics · FRQs · Rotation.

When to use which law

Situation	Tool
Springs, height, speed	Energy conservation
Variable force along path	W = ∫F·dx
Two bodies collide	Momentum conservation
Explosion / recoil	Momentum + energy if asked

Calculus reminders

• Power: P = F·v (dot product).
• Centre of mass: ∫x dm / M in advanced setups.
• Non-conservative work — include friction loss explicitly.

Frequently asked questions

Elastic vs inelastic?

Check if problem asks for kinetic energy before/after.

Rotation + momentum?

Angular momentum — rotation revision.

Practice tests?

Practice exams.

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