Physics
Part I: Sections IV
(Emphasis is on translational motion, forces and torque, work and
energy, periodic motion, and fluids and fluid dynamics.)
At the beginning of each of the 10 sections in the Physics Review Books (2017
edition) is a page listing the "Selected equations, facts, concepts, and
shortcuts" for that particular section. After reading the text in each section
and completing the accompanying MCATstyle passages, we feel that you will have a
better conceptual understanding of the material important to the physics found in
the Chemical and Physical Foundations of Biological Systems section of the MCAT.
Section I: Translational
Motion
Section Goals
 Understand how to work with units and
dimensions. The most widely used system of units in the world is the metric
system. Physical measurements consist of counting.
 Have a working
understanding of the difference between scalar and vector quantities. Physical
quantities are classified and manipulated according to whether they are scalars
or vectors. Scalar quantities have magnitude only. They have no direction in
space. Some examples include time, mass, temperature, electric charge, and
chemical concentrations. Vectors are quantities that have both magnitude and
direction. Some examples of vector quantities include displacement, velocity,
acceleration, force, and torque.
 Know how to manipulate vectors.
Understand how to add, subtract, and multiply vectors; understand that vector
components are independent of one another. Know the difference between a dot
(a.k.a. scalar or inner) product and a cross (a.k.a. vector or outer) product.
The dot product and the cross product are completely different from one another.
Know how to apply the right hand rule to a cross product.
 Understand
the definitions of the sine, cosine, and tangent functions for a right triangle.
A right triangle has a hypotenuse, an angle theta, a side opposite to the angle
theta, and a side adjacent to the angle theta. Know that Sin (theta) =
opposite/hypotenuse, Cos (theta) = adjacent/hypotenuse, and that Tan (theta) =
opposite/adjacent.
 Be familiar with the three basic types of motion.
Translational motion involves the movement of an object from one place to
another. Rotational motion examines how an object rotates about an axis.
Vibrational motion examines how an object moves back and forth about some central
point or axis. In this section, we will primarily be examining translational
motion. In later sections, there will be times when we will discuss the
combination of translational motion with both rotational and vibrational
motion.
 Know the difference between speed, velocity, and
acceleration. Speed is defined as distance traveled divided by time. Velocity is
the rate of change of displacement. Velocity and speed are often confused with
one another. Velocity requires the identification of a direction (vector); speed
does not (scalar). The dimensions of velocity are the dimensions of length
divided by the dimensions of time. The rate of change of velocity with respect to
time is referred to as acceleration. The physical dimensions of acceleration are
the units of velocity divided by the units of time.
 Understand the
concepts behind uniformly accelerated motion in the xdirection. In this section
we examine the four equations of uniformly accelerated motion. Memorize them! It
is important to keep in mind that these four equations are only valid when the
acceleration of an object is constant.
 Be able to describe a freely
falling body. The average acceleration of gravity near the surface of the earth
is about 9.8 m/s2 or 32.2 ft/s2. "Average" is used because very precise
measurements of the acceleration of gravity will tell us that it is not exactly
the same at all locations on the Earth.
 Be able to modify the four
equations for uniformly accelerated motion in the xdirection. Assuming the
gravitational acceleration is constant, one can modify the equations for
uniformly accelerated motion in the xdirection to fit uniformly acceleration
motion in the ydirection. Understand why it is common when doing problems with
these equations to replace "a" with "g." Know what the minus sign
implies.
 Know how to solve problems involving projectiles. Be aware
that what takes place in the xdirection and what takes place in the ydirection
are two independent and separate quantities. Understand how to quickly separate
parts of a given problem into a horizontal component and a vertical component.
Passages and Solutions
Section I includes 6 MCATstyle passages with detailed solutions.
Passage topics are centered around information important to translational motion.
Section Goals
 Know the difference between kinematics and
dynamics. Kinematics involves the description and analysis of motion without
saying what caused it. Dynamics is the study of the forces that are responsible
for producing changes in motion. Newton's three laws form the cornerstone of this
topic.
 Understand Newton's First Law and its applications. An object
at rest will remain at rest and an object in motion will continue to move with
uniform velocity in a straight line, unless acted upon by an external force. Be
aware that this law is not true for all reference frames. In order for this law
to be true an inertial reference frame must be established.

Understand Newton's Second Law and its applications. A force acting on an object
will give that object an acceleration in the direction of the force. The
acceleration of the object is directly proportional to the resultant force
applied to the object and inversely proportional to the mass of the object. Quite
simply, this law is expressed as F = ma, where force (F) and acceleration (a)
have both magnitude and directionmeaning they are vector quantitieswhile mass
(m) is a scalar.
 Understand Newton's Third Law and its applications.
If one object exerts a force on a second object, the second object will exert a
reaction force which is equal in magnitude but opposite in direction on the first
object.
 Understand the concepts behind frictional forces. The
frictional force between one solid and another solid depends on the composition
of the two materials, and on how tight the surfaces are being pressed together.
Friction tends to oppose the motion of movement of an object. Be familiar with
the differences between the static and kinetic coefficients of friction.
 Understand how inclined planes work. When considering inclined planes, it is
especially important to know how to break forces into components. Know why
choosing a coordinate system perpendicular (the yaxis) and parallel (the xaxis)
to the plane of the incline is key in solving these types of problems.
 Be familiar with the operation of pulleys. Pulleys are systems that are used
to change the direction of a given force. A system of multiple pulleys can be
used to reduce a force needed to lift a heavy object. Understand the concept of a
mechanical advantage.
 Be familiar with torques. A torque is a
measurement of the ability of a force to cause rotation about a given pivot
point. Understand the meaning of words or phrases like fulcrum, line of action,
and moment (lever) arm.
 Be familiar with the equation for
calculating torques. Know how to do simple calculations to find the magnitude of
the torque about some point. Know that torques can be represented in terms of a
vector product. Be familiar with vector products and their direction in space.
Understand why vector C, the vector product of A and B, is perpendicular to both
A and B. Be able to determine if vector C points into or out of the plane defined
by vectors A and B. Know the righthand rule. Understand why torques in the
counterclockwise direction are taken to be positive while torques in the
clockwise direction are taken to be negative.
 Be familiar with
translational and rotational equilibrium. Know what two conditions must apply for
a rigid body to be in both translational and rotational equilibrium.
Passages and Solutions
Section II includes 6 MCATstyle passages with detailed solutions.
Passage topics are centered around information important to forces and torque.
Section Goals
 Know the definition of work. Work is defined as
the force exerted on an object as that object undergoes a displacement. The work
done by a constant force on an object is just the force times the component of
displacement parallel to the direction of the applied force. This is expressed as
W = (F)(delta x). Work is a scalar quantity; the units are in joules.
 Understand how energy and work are related. Energy is defined as the ability
to do work. Know that energy can be classified as either kinetic energy or
potential energy.
 Understand the relationship between kinetic energy
and work. Kinetic energy is the ability of an object to do work because of its
motion. Know that the net work done on an object equals the change in the kinetic
energy of that object.
 Understand the meaning of potential energy.
Potential energy is the ability of an object to do work because of its position
or configuration. Know that potential energy can only be defined for certain
kinds of forces.
 Understand the relationship between gravitational
potential energy and work. The work done on an object against the gravitational
force is defined as the change in the gravitational potential energy of that
object. An object has potential energy if that object has some vertical height
above a reference height.
 Know that gravitational potential energy
depends only on the initial and final heights of an object. Gravitational
potential energy does not depend on the path an object takes as it moves upwards
or downwards.
 Realize that potential energy can be stored in an
object due to its shape. In this case the classic example is a compressed spring.
The energy stored in a compressed spring can be used to do work. This potential
energy is missing in a relaxed spring. Understand how to find the amount of work
done in compressing a spring.
 Know that total energy is conserved.
The total energy in the universe is constant. Energy cannot be created nor can it
be destroyed, only changed into different forms.
 Be familiar with
mechanical energy. The mechanical energy represents the total capacity of an
object to do work. The mechanical energy is just the sum of the kinetic and
potential energies of an object, and is usually given the symbol E.

Be able to define power. Power is the rate of doing work and is expressed in
units of watts. Know the simple conversion of watts to horsepower.
Passages and Solutions
Section III includes 6 MCATstyle passages with detailed solutions.
Passage topics are centered around information important to work and energy.
Section Goals
 Know the difference between periodic motion and
simple harmonic motion. Periodic motion is any motion that repeats itself in a
fixed time interval. Examples include the orbital motion of a satellite, the
vibration of a guitar string, the swinging of a pendulum. If an object is
undergoing a special type of periodic motion called simple harmonic motion, then
the acceleration of that object undergoing is proportional to the negative of its
displacement. A graph of its displacement as a function of time is that of a sine
or cosine function.
 Understand the characteristics of simple
harmonic motion. This type of motion involves a period, a frequency, and an
amplitude. Know how to relate the period to the frequency. Remember that the
period is independent of the amplitude.
 Have a general understanding
of Hooke's law and its applications. The displacement of a spring from
equilibrium is proportional to the force acting to displace that spring. This
proportionality can be written as F = kx, where k is a force constant that
depends on the stiffness of the spring.
 Be familiar with the simple
harmonic motion of a spring and a pendulum. Understand the similarities and
differences between the expression used to calculate the frequency of a vibrating
spring and the frequency of a swinging pendulum.
 Be able to define a
wave. A wave is defined as a transmission of energy through a material. Know that
waves carry energy and momentum, but they do not carry mass.
 Know
what the basic wave characteristics are. All waves have an amplitude, a
frequency, a wavelength, a wave speed and they carry energy. Know what the
relationship is between these various quantities. Know when the wave frequency of
a wave will be constant and when it will change.
 Be familiar with
the differences between transverse and longitudinal waves. Transverse waves cause
vibrations perpendicular to the direction of wave propagation while longitudinal
waves cause vibrations parallel to the direction of wave propagation. It is
important to understand the relationships between amplitude, frequency,
wavelength, and the velocity of waves.
 Understand the principle of
superposition of waves. This principle says that if two or more waves passing
through the same medium meet at a particular point in that medium, then the net
displacement of those waves is just the addition of the individual displacements
of the waves if they were traveling through the medium alone. Be familiar with
constructive and destructive wave interference.
 Understand why
standing waves do not appear to travel along their line of propagation. Know how
to recognize the standingwave vibration patterns on a string. Understand the
meaning of a harmonic, an overtone, a node, and an antinode.
 Be
familiar with resonance. Understand why the amplitude and hence the energy of the
system may increase if one supplies a vibrating force that has a frequency which
is the same as the natural frequency of the system.
Passages and Solutions
Section IV includes 6 MCATstyle passages with detailed solutions.
Passage topics are centered around information important to periodic motion.
Section V: Fluids and
Fluid Dynamics
Section Goals
 Know the difference between density and specific
gravity. The density of a material is simply the mass divided by the volume. The
specific gravity of a material is the ratio of its density to that of water at 4
degrees Celcius.
 Be able to work with pressures and understand
Pascal's principle. Pressure can be defined as the ratio of the magnitude of a
force to the perpendicular are over which that force acts. Pascal's principle
states that a pressure applied to a closed fluid is transmitted equally
throughout the fluid and to the walls of the fluid's container.
 Be
able to work with buoyancy and Archimedes' principle. Archimedes' principle
states that objects wholly or partially submerged in a fluid is supported by a
force whose magnitude is equal to the weight of the fluid displaced by the
object. This force is called the buoyant force.
 Understand how to
use the expression for continuity. Because liquids are incompressible, the flow
rate (the amount of volume per time) of such a fluid through a tube must be a
constant. This leads to the equation of continuity, which states that the volume
of fluid entering one end of a tube per time must be equal to the volume of fluid
leaving the other end of the tube in the same amount of time. This means that if
the crosssectional area of the tube changes, then the speed of the fluid must
also change.
 Know how to use Bernoulli's equation. Be familiar with
what happens to a fluid as it flows through a pipe in terms of its kinetic
energy, gravitational potential energy, and work done on the system.

Be able to work with viscosity and Poiseuille's principle. Friction in fluids is
referred to as viscosity. Understand what leads to an increase or a decrease in
the viscosity of a fluid. Understand the meaning of the parameters in the
expression for Poiseuille's principle.
 Understand the difference
between laminar and turbulent flow. If adjacent layers of a fluid are able to
slide past one another, the flow is said to be laminar. If a chaotic and
irregular pattern of fluid flow develops, then the flow is said to be turbulent.
Understand the meaning of the Reynolds number.
Passages and Solutions
Section V includes 6 MCATstyle passages with detailed solutions.
Passage topics are centered around information important to fluids and fluid
dynamics.
At the end of Book I are five diagnostics, each with 9 passages, free
standing questions, and detailed solutions.
SAMPLE PASSAGE
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