MCAT Physics: The 25 Equations You Must Memorize

Unlike many college physics exams, the MCAT does not provide a formula sheet. You need these equations memorized cold. The good news: you don't need hundreds of formulas. These 25 cover about 90% of the physics questions you'll see.

Mechanics (6 equations)

1. Kinematics: v = v₀ + at   |   x = v₀t + ½at²   |   v² = v₀² + 2ax

Use when: constant acceleration problems (free fall, projectile motion, cars accelerating/braking).

2. Newton's Second Law: F = ma

The most fundamental equation in physics. Use it to connect force, mass, and acceleration in any mechanics problem.

3. Friction: f = μN

Static friction (f_s ≤ μ_sN) vs. kinetic friction (f_k = μ_kN). The MCAT loves inclined plane problems where you resolve forces into components.

4. Work-Energy Theorem: W = Fd cosθ   |   KE = ½mv²   |   PE = mgh

Conservation of energy: KE₁ + PE₁ = KE₂ + PE₂ (when no non-conservative forces do work).

5. Momentum: p = mv   |   FΔt = Δp (impulse)

Conservation of momentum in collisions. Elastic = KE conserved. Inelastic = KE not conserved.

6. Torque: τ = rF sinθ

For rotational equilibrium: Στ = 0. Common in lever/fulcrum problems.

Fluids (3 equations)

7. Pressure: P = F/A   |   P = ρgh (hydrostatic)

8. Buoyancy: F_b = ρ_fluidV_displacedg (Archimedes' principle)

Object floats when F_b = mg. Object sinks when ρ_object > ρ_fluid.

9. Continuity & Bernoulli: A₁v₁ = A₂v₂   |   P + ½ρv² + ρgh = constant

Bernoulli is the most tested fluid equation. When cross-section decreases, velocity increases and pressure decreases.

Waves & Optics (4 equations)

10. Wave equation: v = fλ

11. Doppler effect: f' = f(v ± v_observer)/(v ∓ v_source)

Approaching = higher frequency. Receding = lower frequency.

12. Snell's Law: n₁sinθ₁ = n₂sinθ₂

13. Thin Lens: 1/f = 1/d_o + 1/d_i   |   m = -d_i/d_o

Positive d_i = real image. Negative d_i = virtual image. |m| > 1 = magnified.

Electricity & Magnetism (5 equations)

14. Coulomb's Law: F = kq₁q₂/r²

15. Electric field & potential: E = F/q = kQ/r²   |   V = kQ/r   |   V = Ed

16. Ohm's Law: V = IR   |   P = IV = I²R = V²/R

17. Resistors: Series: R_total = R₁ + R₂   |   Parallel: 1/R_total = 1/R₁ + 1/R₂

18. Capacitors: C = Q/V = ε₀A/d   |   E = ½CV²

Capacitors add opposite to resistors: parallel = add, series = reciprocal add.

Thermodynamics (4 equations)

19. Heat: q = mcΔT   |   q = mL (phase change, no temperature change)

20. Ideal Gas Law: PV = nRT

21. First Law: ΔU = q - W   (or ΔU = q + W depending on convention)

22. Entropy: ΔS = q_rev/T

Nuclear & Atomic (3 equations)

23. Radioactive decay: N = N₀(1/2)^t/t_1/2

24. Photoelectric effect: KE_max = hf - φ (work function)

25. de Broglie wavelength: λ = h/p = h/mv

The Secret to MCAT Physics

The MCAT rarely asks you to plug numbers into an equation. It asks you to reason about relationships. For example: "If the radius of a blood vessel doubles, by what factor does blood flow increase?" (Answer: 16x, by Poiseuille's law — flow is proportional to r⁴).

Practice identifying which equation applies to a given scenario, and understanding the proportional relationships within each equation. That skill is worth more than memorizing formulas.

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