MCAT Physics: The Ultimate Prep Guide

MCAT Physics Review: How Much Physics is on the MCAT?

Questions concerning physics are only found in the first section of the MCAT: The Chemical and Physical Foundations of Biological Systems. This section of the MCAT consists of 59 questions with only 25% of questions related to introductory physics. Some of the questions are passage-based and some are discrete.

Only 25% of MCAT CPBS section covers physics!

You will have 95 minutes to complete this section of the exam. You will not be provided with a calculator, but you will be supplied with the MCAT periodic table. The physics content that is featured in the MCAT is covered in introductory courses or prerequisites for medical school.

“The MCAT physics section covers a vast range of concepts, and even with a solid foundation, I encountered a lot of difficulties applying the specific details and nuances needed to answer questions quickly. The time constraint adds another layer of difficulty for me. Building a strong conceptual foundation was crucial … Creating detailed diagrams for each topic and an equation sheet with key formulas helped me visualize and recall information quickly. Explaining concepts to myself out loud also solidified my understanding.” – Dr. Cathleen Kuo, MD

The MCAT does not demand you to be a physics expert. Even so, acing MCAT physics questions can be challenging for students who struggle with physics, so it’s vital to review MCAT physics concepts and high-yield MCAT topics.

“My weakest section was physics. The MCAT strategy that worked for me was knowing what I was up against (question subject breakdown) and focusing on what I could realistically review in the time that I had. I didn’t have time to relearn all of general physics [so] I focused on refining my strongest points, reviewing topics I had grasped previously, and focusing on high yield for the items I didn’t know.” – Dr. Monica Taneja, MD, University of Maryland School of Medicine.

Next, we’ll cover the MCAT physics topics you MUST know for the MCAT so know where to focus your prep.

MCAT Physics Review: What Physics Concepts Are on the MCAT?

Your physics knowledge will be tested in two subsections of the Chemical and Physical Foundations of Biological Systems section of the MCAT. Most of the physics content will be covered in the Foundational Concept 4 subsection, with some physics present in the Foundational Concept 5 subsection.

Foundational Concept 4

Human bodies are complex living organisms that transport materials, sense their environment, process signals, and respond to changes using processes that follow the laws of physics. They can be analyzed and understood by using equations that model behavior at a fundamental level. Basic physics equations and concepts inform your knowledge of the physiological functions of the human body, including respiratory, cardiovascular, and neurological systems. As a future physician you must be familiar with the following Foundational Concept 4 themes and their related concepts:

Category 4A focuses on motion and its causes, and various forms of energy and their interconversions.

Translational Motion

• Units and dimension
• Vectors, components
• Vector addition
• Speed, velocity (average and instantaneous)
• Acceleration

Force

• Newton’s Frist Law, inertia
• Newton’s Second Law (F=ma)
• Newton’s Third Law, forces equal and opposite
• Friction, static and kinetic
• Center of mass

Equilibrium

• Vector analysis of forces acting on a point object
• Torques, lever arms

Work

• Work done by a constant force: W=Fd cosϴ
• Mechanical advantage
• Work Kinetic Energy Theorem
• Conservative forces

Energy of Point Object Systems

• Kinetic Energy: KE = ½ mv2 ; units
• Potential Energy: PE = mgh (gravitational, local); PE = ½ kx2 (spring)
• Conservation of energy
• Power, units

Periodic Motion

• Amplitude, frequency, phase
• Transverse and longitudinal waves: wavelength and propagation speed

Category 4B focuses on the behavior of fluids, which is relevant to the functioning of the pulmonary and circulatory systems.

Fluids

• Density, specific gravity
• Buoyancy, Archimedes’ principle
• Hydrostatic pressure: Pascal’s Law and Hydrostatic pressure P=pgh (pressure vs. depth)
• Viscosity: Poiseuille Flow
• Continuity equation (A∙v = constant)
• Concept of turbulence at high velocities
• Surface tension
• Bernoulli’s equation
• Venturi effect, pitot tube

Gas Phase

• Absolute temperature, (K) Kelvin Scale
• Pressure, simple mercury barometer
• Molar volume at 0°C and 1 atm = 22.4 L/mol
• Ideal gas: definition, Ideal Gas Law PV=nRT, Boyle’s Law PV=constant, Charles’ Law V/T=constant, Avogadro’s Law V/n-=constant
• Kinetic Molecular Theory of Gases: heat capacity at constant volume and at constant pressure and Boltzmann’s Constant
• Deviation of real gas behavior from Ideal Gas Law: qualitative and quantitative (Van der Waal’s Equation)
• Partial pressure, mole fraction
• Dalton’s Law relating partial pressure to composition

Category 4C highlights the nature of electrical currents and voltages; how energy can be converted into electrical forms that can be used to perform chemical transformations or work; and how electrical impulses can be transmitted over long distances in the nervous system.

Electrostatics

• Charge, conductors, charge conservation
• Insulators
• Coulomb’s Law
• Electric field E: field lines and field due to charge distribution
• Electrostatic energy, electric potential at a point in space

Circuit Elements

• Current I = ΔQ/Δt, sign conventions, units
• Electromotive force, voltage
• Resistance: Ohm’s Law I=V/R, Resistors in series, Resistors in parallel, Resistivity ρ = R•A / L
• Capacitance: parallel plate capacitor, energy of charged capacitor, capacitors in series, capacitors in parallel, dielectrics
• Conductivity: metallic and electrolytic
• Meters

Magnetism

• Definition of magnetic field B
• Motion of charged particles in magnetic fields; Lorentz force

Watch this video to learn the MCAT physics equations you need to know!

Category 4D emphasizes the properties of lights and sound; how the interactions of light and sound with matter can be used by an organism to sense its environment; and how these interactions can also be used to generate structural information or images.

Sound

• Production of sound
• Relative speed of sound in solids, liquids, and gases
• Intensity of sound, decibel units, log scale
• Attenuation (Damping)
• Doppler Effect: moving sound source or observer, reflection of sound from a moving object
• Pitch
• Resonance in pipes and strings
• Ultrasound
• Shock waves

Light, Electromagnetic Radiation

• Concept of Interference; Young Double-slit Experiment
• Thin films, diffraction grating, single-slit diffraction
• Other diffraction phenomena, X-ray diffraction
• Polarization of light: linear and circular
• Properties of electromagnetic radiation: velocity equals constant c, in vacuo
• Electromagnetic radiation consists of perpendicularly oscillating electric and magnetic fields; direction of propagation is perpendicular to both
• Classification of electromagnetic spectrum, photon energy E=hf
• Visual spectrum, color

Geometrical Optics

• Reflection from plane surface: angle of incidence equals angle of reflection
•  Reflection, refractive index n; Snell’s law: n1 sin θ1 = n2 sin θ2
• Dispersion, change of index of refraction with wavelength
• Conditions for total internal reflection
• Spherical mirrors: center of curvature, focal length, and real virtual images
• Thin lenses: converging and diverging lenses, use of formula 1/p + 1/q = 1/f, with sign conventions, and lens strength, diopters
• Combination of lenses
• Lens aberration
• Optical Instruments, including the human eye

Category 4E focuses on subatomic particles, the atomic nucleus, nuclear radiation, the structure of the atom, and how the configuration of any particular atom can be used to predict its physical and chemical properties.

Atomic Nucleus

• Atomic number, atomic weight
• Neutrons, protons, isotopes
• Nuclear forces, binding energy
• Radioactive decay: α, β, γ decay and half-life, exponential decay, semi-log plots
• Mass spectrometer
• Mass spectroscopy

Electronic Structure

• Orbital structure of hydrogen atom, principal quantum number n, number of electrons per orbital
• Ground state, excited states
• Absorption and emission line spectra
• Use of Pauli Exclusion Principle
• Paramagnetism and diamagnetism
• Conventional notation for electronic structure
• Bohr atom
• Heisenberg Uncertainty Principle
• Effective nuclear charge
• Photoelectric effect

Foundational Concept 5

This subsection of the MCAT contains only one physics content area, but keep in mind that all of these concepts are related, whether they are organic chemistry, biochemistry, or physics. Foundational Concept 5 subsection covers the following content and related physics concepts:

Category 5A emphasizes the nature of solution formation, factors that affect solubility, and the properties and behavior of aqueous solutions, with special emphasis on the acid-base behavior of dissolved solutes.

Category 5B focuses on molecular structure and how it affects the strength of intermolecular interactions.

Category 5C emphasizes how differential intermolecular interactions can be used to effect chemical separations.

Category 5D emphasizes the varied nature of biologically-relevant molecules, and how patterns of covalent bonding can be used to predict the chemical reactivity of these molecules and their structure and function within a living system.

Category 5E emphasizes how relative energy dictates the overall favourability of chemical processes and the rate at which these processes can occur.

Energy Changes in Chemical Reactions - Thermochemistry, Thermodynamics

• Thermodynamic system – state function
• Zeroth Law – concept of temperature
• First Law − conservation of energy in thermodynamic processes
• PV diagram: work done = area under or enclosed by curve
• Second Law – concept of entropy: entropy as a measure of “disorder” and relative entropy for gas, liquid, and crystal states
• Measurement of heat changes (calorimetry), heat capacity, specific heat
• Heat transfer – conduction, convection, radiation
• Endothermic/exothermic reactions: enthalpy, H, and standard heats of reaction and formation and Hess’ Law of Heat Summation
• Bond dissociation energy as related to heats of formation
• Free energy: G
• Spontaneous reactions and ΔG°
• Coefficient of expansion
• Heat of fusion, heat of vaporization
• Phase diagram: pressure and temperature

How to Review for MCAT Physics

1. Remember, it’s Not as Scary as it Looks

Most physics passages look intimidating in practice tests, but the questions typically only require equation manipulations or application of very basic principles. Prioritize reviewing equations and concepts that are outlined in the AAMC’s official content list. Don’t get bogged down by complicated material that has almost no chance of appearing on the test.

“Understanding the questions since they can be so complex and figuring out how to integrate an appropriate equation can be difficult. [I would] read a lesson then do questions immediately after in order to apply what I learned and see how much I understood the material.” – Dr. Christian Cuevas, MD

2. Know Your Units

You must know how to convert between units without a calculator. Get comfortable performing quick unit conversions because sometimes that’s all you need to do to find the correct answer among the MCAT answer options. Practice messing with one of the variables to see what happens to the rest of the equations – if you can easily isolate individual variables and solve the equation every time, it demonstrates your thorough understanding of the equation.

“I think practice questions were particularly useful with physics and I would often integrate more ‘practice quizzes’ over reading when approaching this topic.” – Dr. Tony Huynh, DO

3. Flashcards and Memorization

Many students use flashcards as a memorization technique. While writing down formulas, concepts, and ideas on flashcards may be a great way to start your MCAT prep, they cannot be the only prep technique you use. Rather than simply memorizing them, you must understand these equations to be able to use them on any problem you encounter.

“Watching YouTube videos and doing flashcards was a great way to learn the content and review the study material on days that I was not doing passage-based questions … [I learned] about physics topics using real-life examples (i.e., pendulum, spring, etc.)” – Dr. Neel Mistry, MD

4. Practice, Practice, Practice

Understanding physics equations and concepts takes practice. If you are really worried about your physics knowledge, work to build your understanding through practice and internalize the concepts you cover. Keep in mind the MCAT looks to establish if you understand broader concepts outlined in the AAMC content list, so don’t get bogged down by the nitty-gritty details of complex physics concepts and equations.

“The hardest part of physics was remembering the different formulas and knowing which one to use when. Doing practice questions to become accustomed to different physics concepts, I found that repetition is key … the more questions I did, the better I got.” – Dr. Neel Mistry, MD.

5. Employ Active Learning

Using active study strategies will help you internalize physics concepts. In addition to reading and making notes, you can explain what you learn to others, draw diagrams or absorb the concepts through means other than dry textbooks. It’s easy to burn out on studying for this section, so keep yourself engaged.

“To avoid burnout, I incorporated short breaks with activities like going for walks or listening to science podcasts. I also found physics-related documentaries and engaging YouTube channels that helped me learn in a more interactive way. Discussing challenging problems with classmates added a social aspect to studying, making it more fun and motivating” – Dr. Cathleen Kuo, MD.

6. Get a Tutor for MCAT Physics

You do not need to have scholarly knowledge of physics to get a great MCAT score. While you are strongly encouraged to take some introductory physics classes during your undergraduate, some students forego them. If you're struggling with your physics prep, it might be wise to get an MCAT tutor who can help you go over the necessary MCAT physics equations.

MCAT Physics Sample Questions

Passage

The heme enzyme indoleamine 2,3 dioxygenase (IDO) catalyzes Reaction 1, the first and rate-determining step of L-tryptophan (Compound 1) metabolism, and is an important enzyme of the human immune system.

Reaction 1

The IDO-catalyzed oxidation of Compound 1 by H2O2 does not occur. However, researchers have recently discovered that IDO-catalyzed oxidation of indole (Compound 3) by H2O2 (Reaction 2) does occur.

Reaction 2

Under the conditions employed, the number of catalytic turnovers appeared to stop at roughly 100, on average. A plot of the concentration of Compound 3 that was oxidized versus the concentration of H2O2 employed, at two different initial concentrations of IDO, gave the results shown in Figure 1.

Aerobic oxidation of Compound 3 in the presence of 18O-labeled H218O2 resulted in the formation of 18O-labeled oxidation products (Table 1).

The formation of Compound 6 does not appear to be the result of a sequential oxidation process. Isotopically labeled Compound 4 does not exchange 18O for 16O in water over 3 hours, but Compound 6 completely loses its 18O label in unlabeled water over the same time period.

Adapted from: Kuo HH, Mauk AG. Indole peroxygenase activity of indoleamine 2,3-dioxygenase. Proceedings of the National Academy of Sciences of the United States of America. 2012;109(35):13966–71.

Practice Questions and Answers

1. The progress of Reaction 2 can be monitored by observing what change to the IR spectrum of the product mixture?

2. The following kinetic parameters were obtained for the IDO-catalyzed oxidation of Compound 3 by H2O2 in the presence of L-Trp.

Based on this data, what effect does L-Trp have on the reaction?

3. Which experiment can be used to show that Compound 6 is not formed sequentially from either Compound 4 or Compound 5?

FAQs

To your success,

Your friends at BeMo

BeMo Academic Consulting 

Source: AAMC Sample Question Guide

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