MCAT physics for biology majors: kinematics, optics, and circuits in 4 weeks

Kinematics and Newtonian mechanics: less math than you remember

MCAT kinematics rarely requires the full toolkit you used in introductory physics. The test focuses on conceptual understanding of motion and a small handful of equations applied to biological or medical contexts.

The four kinematic equations cover constant-acceleration motion: v = v₀ + at, x = v₀t + ½at², v² = v₀² + 2ax, and x = ½(v + v₀)t. Master the conditions under which each is useful (when you know which variables and which you need to find) and you can solve almost any straight-line kinematics problem in under a minute.

Newton's laws layer on top. F = ma is the workhorse. The test loves to combine forces (gravity, normal force, friction, tension) in pulley or inclined-plane scenarios that look mechanical but often have biological framing — a falling object representing a dropped instrument, a friction problem framed as joint motion.

• Master the 4 kinematic equations; know when to use each.
• Free-body diagrams before equations, every time.
• Gravity = 10 m/s² is close enough for MCAT estimation.

Conceptual mastery beats memorized formulas. Draw the picture before you write the equation.

Work, energy, and conservation: the most useful single principle

Conservation of energy is the most powerful tool in MCAT physics. Many questions that look complex become simple when you set up an energy balance: initial kinetic plus potential equals final kinetic plus potential, plus any energy added or lost to friction or other dissipative forces.

Kinetic energy is ½mv². Gravitational potential energy is mgh. Elastic potential energy (in springs) is ½kx². Work is force times distance in the direction of motion. Power is work per unit time. These five equations cover the vast majority of energy questions.

Biological framings are common: muscle contraction as work, blood flow as fluid power, metabolism as energy transformation. The physics is identical to mechanical examples; the framing is just biological.

When mechanics looks hard, try energy conservation first.

Fluids: pressure, flow, and continuity

Fluid physics has high biological yield because the cardiovascular and respiratory systems are fluid systems. The MCAT loves to use blood flow, blood pressure, and lung mechanics as physics question contexts.

Pressure is force per area. Hydrostatic pressure increases with depth: P = ρgh. Atmospheric pressure is about 10⁵ Pa, useful as a reference for biological pressures.

Continuity says that for an incompressible fluid in a closed system, A₁v₁ = A₂v₂. When a tube narrows, flow speed increases. Bernoulli's equation connects pressure, velocity, and height in flowing fluids: where flow is faster, pressure is lower. Both equations show up directly in cardiovascular questions about narrowed arteries and changes in flow velocity.

• Pressure increases with depth in static fluids.
• Continuity: narrower tube means faster flow.
• Bernoulli: faster flow means lower pressure.
• Apply these directly to blood vessels and airways.

Optics and circuits: small topics, recurring on the test

Optics shows up consistently but rarely as the focus of a whole passage. The reliable topics: thin lens equation (1/f = 1/d_o + 1/d_i), magnification (m = -d_i/d_o), and the difference between converging and diverging lenses. Eye-related physiology (myopia, hyperopia, corrective lenses) is a recurring biological application.

Circuits are similar — narrow, predictable, and worth knowing well. Ohm's law (V = IR), power (P = IV = I²R = V²/R), and the rules for series (resistance adds) vs parallel (1/R_total = sum of 1/R_i) cover most circuit questions. Capacitors and RC circuits appear less often but are worth a quick review.

• Lens equation + magnification + lens type covers most optics.
• Ohm's law + power + series/parallel covers most circuits.
• RC circuit time constant: τ = RC (worth memorizing).

How to prep physics in 4 weeks if it's your weakest section

If you have four weeks and physics is your weak spot, do not start with a physics textbook. Start with a content review summary specifically built for MCAT physics, then move to passages immediately. Spend more time on review than on initial content acquisition — most physics gains come from working through problems and naming what tripped you up.

Aim for 4 to 6 physics passages per week with thorough review. Track which topic categories generate the most misses and concentrate the next week's content time on those categories. By week four, you should be doing mostly mixed-passage practice with content review only on confirmed weak topics.

• Week 1: Kinematics, Newton's laws, energy.
• Week 2: Fluids, thermodynamics, electrostatics.
• Week 3: Circuits, optics, waves and sound.
• Week 4: Mixed passage practice + targeted review only.

Sources

• AAMC content outline: Chemical and Physical Foundations — AAMC