AP Physics FRQ Guide

FRQ Section Structure

Exam	FRQ Section	Time	Questions
AP Physics 1	Section II	90 minutes	3 long + 3 short FRQs
AP Physics C: Mechanics	Section II	45 minutes	3 FRQs
AP Physics C: E&M	Section II	45 minutes	3 FRQs

FRQs are worth 50% of the total exam score. Each question has multiple sub-parts, each with its own point value.

The FRQ Answer Framework

Step 1: Read the whole question first

Before writing anything, read all sub-parts. Later sub-parts often give context clues for earlier ones, and understanding the full scope prevents wasted work on approaches the question doesn't require.

Step 2: Draw a labelled diagram

For any problem involving forces, fields, motion, or circuits — draw a diagram immediately. A correct free body diagram (FBD) earns a dedicated point on most FRQs. Label all forces with their names (not just arrows), and indicate direction clearly.

FBD checklist: Object represented as a dot or box; all forces drawn as arrows from the dot; each arrow labelled (N, mg, T, f, etc.); no unnecessary forces (e.g., don't include velocity as a "force").

Step 3: State the principle you're applying

Before writing equations, briefly state what you're using: "Applying Newton's second law in the x-direction," "Using conservation of energy," "Applying Faraday's law." This earns the "reasoning" point and gives you a checkpoint to verify your approach.

Step 4: Write the general equation, then substitute

Write: F_net = ma. Then substitute what you know: T − mg sin θ = ma. Then solve. Never skip straight to numbers — the method marks are in the setup, not the arithmetic.

Step 5: Include units and significant figures

Every numerical answer must have units. Use 2–3 significant figures unless asked otherwise. A unit error costs 1 point; consistent sig fig errors throughout an exam can cost 2–3 points total.

Justification Answers: What Earns Full Credit

Justification questions are one of the most underscored parts of AP Physics FRQs. They require a specific structure:

1. Reference the applicable law or principle by name
2. State what that law says (briefly)
3. Apply it to the specific scenario in the question
4. State the conclusion

Example question: "A block on a frictionless incline is connected to a hanging mass via a string over a pulley. If the hanging mass increases, what happens to the acceleration of the system? Justify."

Full credit answer: "By Newton's second law applied to the system, a = F_net / m_total. Increasing the hanging mass increases the net downward force while also increasing total mass, but the net force increases proportionally faster than mass for these masses, so the acceleration increases."

Zero credit answer: "The acceleration increases because there is more force."

Derivation Questions: Show Every Step

Derivation questions (common on Physics C) ask you to derive an expression from first principles. Graders award points for each logical step, not just the final answer.

• Start from a named fundamental law or equation
• Show every algebraic step — don't skip steps to save time
• Label what each variable represents if it's not obvious
• Box or clearly identify the final expression
• Check that your expression has the right units as a sanity check

Common AP Physics FRQ Topics by Exam

AP Physics 1

• Newton's laws with FBDs (present on almost every exam)
• Energy conservation with friction
• Momentum conservation in collisions
• Rotational motion: torques, rotational inertia
• Simple harmonic motion: spring-mass and pendulum
• DC circuits: Kirchhoff's laws, resistor combinations

AP Physics C: Mechanics

• Calculus-based kinematics (variable force or acceleration)
• Work-energy with variable force: W = ∫F dx
• Rolling without slipping
• Angular momentum conservation
• Oscillations and SHM derivations
• Gravitation and orbital mechanics

Quick Reference: Partial Credit Rules

• Points are independent per sub-part — a wrong answer in (a) does not prevent earning points in (b)
• Error carried forward (ECF): correct method applied to wrong earlier answer earns most points
• Never leave a sub-part blank — a correct equation with no further work still earns 1 point
• Crossed out work is not scored — only final, uncrossed work is graded