AP Physics 2 3-Day Cram Plan

You have three days until the AP Physics 2 exam. This is not the time to learn new material from scratch—it's time to drill the highest-frequency topics and lock in the FRQ patterns the College Board reuses every single year.

This plan assumes ~4 focused hours per day. Skip nothing on the checklist; if you're short on time, shorten the practice sets, not the topic coverage.

Day 1: Fluids & Thermodynamics (4 hrs)

These two units account for roughly 25-30% of the exam. Master them first.

What to review (90 min)

• Pressure fundamentals: $P = \rho g h$ for hydrostatic pressure, Pascal's principle, pressure in fluids at rest.
• Buoyancy: Archimedes' principle, buoyant force $F_b = \rho_{\text{fluid}} V_{\text{displaced}} g$. Always draw a free body diagram with $F_b$ pointing up and $F_g$ pointing down.
• Fluid flow: continuity equation $A_1 v_1 = A_2 v_2$. Narrower pipe → faster flow → lower pressure.
• Thermodynamics foundation: ideal gas law $PV = nRT$, distinguishing heat ($Q$) from temperature ($T$).
• First Law: $\Delta U = Q + W$. Here $W$ = work done on the gas (positive for compression, negative for expansion).
• PV diagrams: reading isobaric (horizontal), isochoric (vertical), isothermal (curved) processes. Area under curve = work.
• Heat engines: efficiency $\eta = 1 - \frac{Q_c}{Q_h}$, Carnot efficiency $\eta_{\text{Carnot}} = 1 - \frac{T_c}{T_h}$.

What to practice (2.5 hrs)

• 15 mixed multiple-choice questions on pressure, buoyancy, and fluid dynamics.
• 1 full FRQ: typically buoyancy (object floating or sinking) with free body diagram justification.
• 1 thermodynamics scenario: read a PV diagram, identify each process, calculate $W$, $Q$, $\Delta U$.

💡 Highest leverage: Buoyancy FRQs almost always ask you to rank objects by density or explain why something floats. Always draw a free body diagram—it's 1 point guaranteed.

⚠️ Sign trap: On PV diagrams, area under the curve is work done by the gas (expansion). Work done on the gas (compression) is negative. Double-check your signs before writing the final answer.

Day 2: Electric Fields, Circuits & Magnetism (4 hrs)

E&M is roughly 35-40% of the exam—the highest-weighted section.

What to review (90 min)

• Coulomb's Law & Electric Field: $F = k\frac{q_1 q_2}{r^2}$ ($k \approx 9 \times 10^9$ N⋅m²/C²), $E = \frac{F}{q} = k\frac{Q}{r^2}$.
• Electric potential: $V = \frac{U}{q} = k\frac{Q}{r}$. Equipotential lines are perpendicular to field lines.
• Circuits: Ohm's law $V = IR$, series $R_{\text{tot}} = R_1 + R_2$ (voltage divides), parallel $\frac{1}{R_{\text{tot}}} = \frac{1}{R_1} + \frac{1}{R_2}$ (current divides).
• Kirchhoff's laws: current conservation at nodes, $\sum V = 0$ around any loop.
• Power & energy: $P = IV = I^2 R = \frac{V^2}{R}$.
• Magnetic force: $F = qvB\sin\theta$ (always perpendicular to $v$), $F = BIL\sin\theta$ on a current-carrying wire. Use right-hand rule.
• Faraday's Law: induced EMF $\mathcal{E} = -\frac{d\Phi_B}{dt}$, Lenz's law (induced current opposes the change in flux).

What to practice (2.5 hrs)

• 20 MCQs: mix of Coulomb's law, electric fields, circuits (series/parallel, Kirchhoff), and Lorentz force.
• 1 full circuit FRQ: multi-loop circuit with batteries and resistors. Use Kirchhoff's laws to find branch currents.
• 1 electromagnetic induction FRQ: moving conductor or changing flux. Apply Faraday's law and Lenz's law.

💡 Circuit shortcut: Always redraw the circuit simplified first. Combine series resistors into one. Then redraw. This prevents node confusion.

⚠️ Lenz trap: Induced current opposes the change, not the field. If upward flux is increasing, induced current creates a downward field. If upward flux is decreasing, induced current tries to maintain it (creates upward field).

Day 3: Optics & Modern Physics + FRQ Full Timed Set (4 hrs)

What to review (90 min)

• Snell's law: $n_1 \sin\theta_1 = n_2 \sin\theta_2$. Total internal reflection when $\sin\theta_1 > \frac{n_2}{n_1}$.
• Lens/mirror equation: $\frac{1}{f} = \frac{1}{d_o} + \frac{1}{d_i}$, magnification $m = -\frac{d_i}{d_o}$ (negative = inverted).
• Ray diagrams: 3-ray method for lenses. Parallel ray through $F$, center ray straight, focal ray exits parallel.
• Wave optics: double-slit bright fringes when path difference $= m\lambda$, single-slit minima when $\frac{a\sin\theta}{\lambda} = m$.
• Thin-film interference: constructive when $2nt = m\lambda$ (normal incidence).
• Photoelectric effect: $E_{\text{photon}} = hf = KE_{\text{max}} + \phi$ (work function).
• Atomic transitions: $\Delta E = hf$. Bohr model: $E_n = -\frac{13.6 \, \text{eV}}{n^2}$.
• Mass-energy: $E = mc^2$. Radioactive decay: $N(t) = N_0 \left(\frac{1}{2}\right)^{t/t_{1/2}}$.

What to practice (2.5 hrs — full timed set)

• 1 optics FRQ: lens or mirror problem (find image position, magnification, draw ray diagram).
• 1 wave optics / polarization MCQ set (8-10 questions).
• 1 modern physics FRQ: photoelectric effect or nuclear decay calculation.
• 25 mixed multiple-choice (all topics), strictly timed.

⚠️ Lens sign trap: Real object/image: positive $d$. Virtual: negative $d$. Converging lens: positive $f$. Diverging: negative $f$. Check your answer. A negative $d_i$ means a virtual image (upright, on the same side as object).

💡 Photoelectric minimum: The photon energy must exceed the work function, not equal it. If $hf < \phi$, zero electrons are emitted (answer is "no photoelectrons").

Night before: Review strategy

Skim our last-minute review checklist. Sleep 8 hours—a rested brain catches sign errors and applies Lenz's law correctly.

Common point-leaks across all 3 days

• Work sign in thermodynamics: $W > 0$ = compression, $W < 0$ = expansion.
• Continuity equation confusion: narrower pipe → faster velocity, not slower.
• Circuit series/parallel: redraw every time to clarify topology.
• Lenz's law direction: opposes the change, not the flux itself.
• Lens equation: watch the signs on $d_o$, $d_i$, $f$.
• Missing units or significant figures on calculations.
• Forgetting to draw and label diagrams (automatic point loss on FRQs).

What this 3-day plan deliberately skips

You will not fully master capacitor circuits (time constant $\tau = RC$), diffraction gratings, or relativistic effects. If weak there: skim 1-2 examples and accept losing 3-4 points. Spend saved time drilling circuits, buoyancy, and optics instead—higher yield.

Ready to start?

Open the AP Physics 2 topic library → and tackle Day 1 fluids first. Mix every topic with at least one worked FRQ. Good luck—you've got this.