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MCAT Physics Equations: Your Simplified Study Guide

July 5, 2022
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MCAT Physics Equations You Need to KnowFAQs: Physics on the MCAT

”Jonathan

Reviewed by:

Jonathan Preminger

Former Admissions Committee Member, Hofstra-Northwell School of Medicine

Reviewed: 5/13/22

Preparing for the physics section on the MCAT and don’t know which equations to prioritize? Keep reading for a quick summary of important MCAT physics equations.

Physics is a notorious part of one of four major sections on the MCAT. Many aspiring doctors are passionate about biology and chemistry and can understand why the MCAT heavily tests these topics. The connection to physics, on the other hand, isn’t always as clear. 

Many doctors use their physics knowledge to keep up with medicine’s current technologies, including X-rays, MRIs, and more. Our bodies also behave according to the rules of physics, and doctors use these rules to diagnose and treat a variety of conditions. Think blood pressure, the neural circuits in our brain, and more. 

Many MCAT physics questions ask for calculations using specific equations. Below we summarize key physics equations you should memorize for the MCAT to help you maximize your study time.

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MCAT Physics Equations You Need to Know

There are several physics topics that you could be tested on the MCAT, including work, kinematics, and sound. Below we summarize the key physics equations for each topic that you could be tested on during the MCAT.

Work, Force, and Energy

Work, force, and energy are the bread and butter of physics. Work is a form of energy that applies force to an object in order to displace it.

Newton’s 2nd Law

F = m x a

The net force (F) on an object can be calculated from the product of the object’s mass (m) and acceleration (A).

Work Done by Constant Force

W = F x d x cosθ 

The work (W) done on an object by a constant force is a product of the magnitude of the force (F) and the direction in which the object is displaced (d) due to this force. Cosine theta (cosθ) is the angle between the object and the force acting on it. 

Work-Kinetic Energy Theorem

Wnet = ΔKE

The total work (Wnet) done by combined forces is proportional to the change of kinetic energy (ΔKE) of an object.

Kinetic Energy 

KE = 1/2 x m x v2

Kinetic energy is proportional to the mass (m) of an object and the square of its velocity (v). 

Potential Energy

PE = m x g x h

The gravitational potential energy (PE) of an object is proportional to the object’s mass (m) and height (h) and to the acceleration of gravity (g = 9.8 m/s2).

Power

P = ΔW/Δt

Power is equal to the amount of work done (W) divided by the time (t).

Kinematics

Kinematics is a field of physics that is all about the motion of objects and systems. Unlike the work and energy section above, kinematic equations do not take into account the forces that cause motion. 

Velocity 

V = V­0 + at 

This equation denotes the velocity of an object under constant velocity at time (t), which equals the initial velocity (V­0) plus the product of acceleration (a) and the time interval.

V2= V02 + 2aΔx

This equation uses the initial velocity, acceleration, and displacement (Δx) to solve for the final velocity. 

Displacement

Δx= V­0 + ½ at2

This equation uses the acceleration, initial velocity, and time interval to solve for displacement for an object under constant acceleration.

Fluid Mechanics

Fluid mechanics is concerned with the mechanisms and forces related to liquids, gases, and plasmas.

Pascal’s Law 

P = F/A

Pascal’s law states that pressure exerted on fluid at rest is transmitted equally in all directions of the container holding said fluid. Pressure is equal to the applied force (F) divided by the area of contact (A).

Bernoulli’s equation

P + ½ pV2 + pgh = constant

Bernoulli’s equation describes how the velocity of the fluid through a tube relates to the pressure of the fluid. P is hydrostatic pressure, p is the fluid density, V is velocity, g is the gravitational acceleration (9.8 m/s2), and h is the height of the fluid. 

Density

p = m/V

The density (p) of a substance is proportional to its mass (m) per unit volume (V).

Specific Gravity

SG = psubsance/pwater 

Specific gravity is the ratio of the density of a substance (psubsance) compared to a reference substance (pwater).

Buoyant force

Fb = pfluid  x V x g

Buoyant force (Fb) is the upward force a fluid exerts on an object. V is the object’s volume, p is the object’s density, and g is the gravitational acceleration.

Hydrostatic pressure

P = P0 + ρgz

Hydrostatic pressure (P) is the pressure (P0) exerted by a fluid at rest due to the force of gravity (g).

Electrostatics and Circuits

This section focuses on how charged particles interact with each other in systems such as circuits.

Coulomb’s Law

F = - k * q1q2/r2

According to Coulomb’s law, like charges repel and opposite charges attract. The force of attraction is proportional to the production of the charges (q1q2); it is inversely proportional to the square of the distance between the charges (r2)

Ohm’s Law

V = IR

Ohm’s law states that voltage (V) across a conductor is proportional to current (I) and inversely proportional to resistance (R). You can rearrange this equation to solve for current or resistance.

Current

I = Q/t

This formula defines how charge flows through an electric circuit as a current (I). It is the quantity of charge flowing (Q) in a time period (t).

Resistance

R = pl/A

This equation gives the resistivity of a wire. It corresponds to the resistivity of the material (p), the length of the wire (l), and the cross-sectional area of the wire (A).

Capacitors in Series

RT = R1 + R2 + …. + RN

This equation denotes total resistance (RT) in a series combination, in which the resistors are connected end-to-end in a circuit. 

Capacitors in Parallel

1/RT = 1/R1 + 1/R2 + …. + 1/RN

This formula denotes total resistance (1/RT) in a series combination, in which the resistors’ terminals are connected to the same two nodes.

Thermodynamics

Thermodynamics is a field of physics that describes how heat relates to work and energy.

Heat phase during change

q = m * Lx

This equation describes the heat (q) required to cause a phase change of a sample of mass m. Lx can be either the latent heat of fusion or the latent heat of vaporization and is the amount of heat necessary to cause a change between a solid and liquid and a liquid and vapor, respectively.

Light

Light is electromagnetic radiation detected by an organism’s eye.

Snell’s law

n1 x sin θ1 = n2 x sin θ2

This equation describes the relationship between refraction (n) and angles of incidence (sin θ) when light passes a boundary separating two media.

Lens equation

1/d0 + 1/di = 1/f

This equation is used to calculate image distance and describes the relationship between object distance (do), image distance (), and focal length (f).

Sound

Sound is a vibration that propagates through air, liquid, and other mediums as a longitudinal wave.

Wave Velocity

V = f x λ

This equation uses the frequency (f) and wavelength (λ) of a wave to calculate the wave’s velocity (V).

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FAQs: Physics on the MCAT

Below are some frequently asked questions about physics on the MCAT.

1. Do You Need to Know All Physics Equations on the MCAT?

It is wise to memorize the key MCAT physics equations summarized above. 

2. Do You Have to Memorize Equations for the MCAT Physics Section?

You are not given a formula sheet on the MCAT, so you will likely need to memorize equations beforehand to successfully answer some physics questions. Some passages may include the equation you will need to use, however.

3. How Should You Memorize Equations for the MCAT Physics Section?

Practice questions! Going through multiple practice questions is a time-effective way of making the MCAT physics equations second nature.

4. Is the MCAT Physics-Heavy?

The Chemical and Physical Foundations of Biological Systems of the MCAT is one of four sections. Of this Chem/Phys section, expect around 25% to 40% of questions to be physics-focused. That’s around 12 to 23 questions out of 230 total questions on the MCAT.

Final Thoughts

Studying MCAT physics equations can be a daunting prospect for many students. While there are quite a few to memorize, pacing yourself, completing practice problems, and having patience will help you ace physics on the MCAT.

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