How to Write AP Physics 1 FRQs
The Free Response section is worth 50% of your AP score. This guide covers how each question type is graded and what you need to do to earn every point.
How FRQs Are Scored
5
Questions in Section 2
90
Minutes total
50%
of your final AP score
Each question is scored by a trained AP reader using a detailed rubric. Points are awarded for correct physics, not for style. Partial credit is always available — never leave a part blank.
💡 AP Tip: Rubric Hunting
The 4 FRQ Types
Short Answer (SA)
2–4 parts, ~4–7 points total
Short answer questions test a single concept or scenario with 2–4 distinct parts (a, b, c…). Each part is worth 1–3 points. They typically ask you to calculate, derive, or explain one focused idea.
Sentence Starters & Templates
Prompt: "Calculate the…"
Start with the equation: [write the equation]. Substitute the known values: [substitution]. Therefore, [quantity] = [answer with units].
Prompt: "Describe what happens to X when Y increases…"
When Y increases, [equation showing relationship]. Therefore, X [increases/decreases/stays the same] because [reason linking to equation or principle].
AP Tips
- •Always start from a fundamental equation — never pull numbers out of thin air.
- •Show every substitution step; graders cannot give credit for invisible work.
- •Include units in every intermediate step, not just the final answer.
Common Mistakes
- ✗Writing only the numerical answer without showing work — zero points awarded.
- ✗Forgetting units on a final answer — usually costs 1 point.
- ✗Using an equation that is not appropriate for the given conditions (e.g., using kinematics equations when energy methods are required).
Long Answer (LA)
5–7 parts, up to 12 points total
Long answer questions are multi-part problems that build on each other. Later parts often depend on earlier results. They may span multiple physics concepts (e.g., kinematics → energy → momentum) in one problem.
Sentence Starters & Templates
Prompt: "Derive an expression for…"
Starting from [fundamental principle or equation]: [write it]. Since [condition], I can substitute [quantity]. This gives: [expression]. Therefore, [final expression].
Prompt: "Justify your answer using physics principles."
By [Newton's Law / conservation of energy / etc.], [state what must be true]. Because [condition in the problem], [conclusion]. Therefore, [restate answer].
AP Tips
- •If you get a wrong answer in part (a), carry it forward into part (b) — graders award "error-carried-forward" credit.
- •Read all parts before starting; later parts often hint at the approach needed for earlier ones.
- •Sketch a diagram or free-body diagram whenever the geometry is unclear — it counts as work.
Common Mistakes
- ✗Skipping a part because it seems hard — even a partially set-up equation earns points.
- ✗Mixing up equations (e.g., using v = fλ in a dynamics problem) — always check the domain.
- ✗Not defining variables you introduce — write "let m = mass of block" if it is not in the problem.
Experimental Design (ED)
Plan an experiment from scratch, ~10–12 points
Experimental design questions ask you to design a procedure to measure a physical relationship or test a hypothesis. You must describe what to measure, how to control variables, and how to use the data.
Sentence Starters & Templates
Prompt: "Design an experiment to determine [quantity]."
Materials: [list specific, measurable equipment]. Procedure: (1) Set up [initial conditions]. (2) Vary [independent variable] by [specific method] while keeping [list controlled variables] constant. (3) Measure [dependent variable] using [instrument] for each value of [IV]. Repeat each trial 3 times and average. Data analysis: Plot [y-axis] vs. [x-axis]. The slope equals [derived relationship]. Calculate [target quantity] from the slope.
AP Tips
- •Always identify: independent variable (what you change), dependent variable (what you measure), controlled variables (what you keep constant).
- •Describe how to linearize data — the AP exam loves "what would you graph to get a straight line?".
- •Mention repeating trials or averaging to address random error — this earns a dedicated point.
- •Specify instruments with precision (e.g., "motion sensor accurate to 0.01 m/s", not just "measure velocity").
Common Mistakes
- ✗Vague procedures like "measure the speed" — specify HOW (photogates, motion sensor, stopwatch + ruler).
- ✗Forgetting to state which variables are controlled (held constant).
- ✗Proposing to measure a quantity that cannot be directly measured (e.g., "measure force" without a force sensor or spring scale).
- ✗Not connecting the data analysis to the target quantity.
Paragraph Argument (PAQ)
Written physics argument, 4–7 points
The Paragraph Argument Question requires a coherent written response — no bullet points, no equations only. You must make a claim, support it with physics reasoning, and link it to evidence. Think of it as a mini physics essay.
Sentence Starters & Templates
Prompt: "Explain why…" or "Argue which scenario…"
[State your claim clearly in one sentence.] This can be understood using [principle/law]. [Explain the principle in 1–2 sentences.] In this scenario, [connect the principle to the specific situation]. Therefore, [restate the conclusion and its physical significance].
AP Tips
- •Start with a direct, specific claim — do not bury your answer in the middle of the paragraph.
- •Name the law or principle explicitly: "By Newton's Third Law…", "Because energy is conserved…".
- •Link cause to effect: do not just state what happens; explain WHY using physics.
- •Write in complete sentences — the PAQ is one of the few places on the exam where communication style matters.
Common Mistakes
- ✗Using bullet points — PAQs require prose; bullets earn zero points for the organization rubric.
- ✗Writing equations only, without any prose explanation.
- ✗Making a claim without justification — a bare assertion earns no argument points.
- ✗Being vague: "the force changes" vs. "the net force increases because friction decreases as surface area decreases".
“Derive” vs “Calculate” — What's the Difference?
DERIVE
Start from a fundamental equation or principle and manipulate it algebraically to reach the target expression. Plugging in numbers first = lose points.
“Starting from F = ma and F_g = mg sinθ − μmg cosθ, dividing by m gives a = g sinθ − μg cosθ.”
CALCULATE
You may start from the relevant equation and substitute numerical values. Show the equation, the substitution, and the result with units.
“a = g sinθ − μg cosθ = (10)(0.5) − (0.3)(10)(0.866) = 5 − 2.6 = 2.4 m/s²”
💡 AP Tip: Justify
Annotated Example FRQ
A model answer with scoring notes for each part.
Question
A 2 kg block slides down a frictionless ramp of height 0.8 m and then collides with a stationary 3 kg block on the flat surface. The two blocks stick together after the collision. (a) Calculate the speed of the 2 kg block at the bottom of the ramp. (b) Calculate the speed of the combined blocks immediately after the collision. (c) Is kinetic energy conserved during the collision? Justify your answer.
Part (a) — 3 pts
Model Answer
Using conservation of energy (no friction): mgh = ½mv². Solving for v: v = √(2gh) = √(2 × 10 × 0.8) = √16 = 4 m/s.
States the correct principle (conservation of energy)
Correct equation setup and algebraic manipulation
Correct numerical answer with units: 4 m/s
Part (b) — 3 pts
Model Answer
Using conservation of momentum (perfectly inelastic collision): m₁v₁ = (m₁ + m₂)v_f. (2)(4) = (2 + 3)v_f. 8 = 5v_f. v_f = 1.6 m/s.
Identifies the correct type of collision and relevant conservation law
Correct momentum equation with substituted values
v_f = 1.6 m/s (correct answer with units)
Part (c) — 3 pts
Model Answer
Kinetic energy is NOT conserved. Before: KE_i = ½(2)(4²) = 16 J. After: KE_f = ½(5)(1.6²) = 6.4 J. Since KE_f < KE_i, kinetic energy decreased. This is a perfectly inelastic collision; energy was converted to heat and deformation.
Correct claim: KE is NOT conserved
Calculates both KE values correctly
Justification: energy converted to thermal/internal energy in inelastic collision