OAR Exam 2025
Scalar - answer quantity that represents only magnitude, e.g., time, temperature, or
volume. It is expressed using a single number, including any units.
vector - answer quantity that represents magnitude and direction. It is commonly used
to represent displacement, velocity, acceleration, or force.
Displacement (s) - answerthe distance and direction of a body's movement (an airplane
flies east 100 nm).
Velocity (V) - answerthe speed and direction of a body's motion, the rate of change of
position (an airplane flies south at 400 knots).
Speed - answera scalar equal to the magnitude of the velocity vector.
Acceleration (a) - answerthe rate and direction of a body's change of velocity (gravity
accelerates bodies toward the center of the earth at 32.174 ft/s2).
force (F) - answera push or pull exerted on a body (1,000 lbs of thrust pushes a jet
through the sky).
Mass (m) - answerthe quantity of molecular material that comprises an
object.
Volume (v) - answerthe amount of space occupied by an object
Density (ρ) - answermass per unit volume. ρ = mass / volume
Weight (W) - answerthe force with which a mass is attracted toward the center of the
earth by gravity.
Force (F) - answermass times acceleration. F = mx a
moment (M) - answercreated when a force is applied at some distance from an axis or
fulcrum, and tends to produce rotation about that point.
Work (W) - answerdone when a force acts on a body and moves it. It is a scalar quantity
equal to the force (F) times the distance of displacement (s).
W=Fxs
Power (P) - answerhe rate of doing work or work done per unit of time.
P =W / t
,Energy - answerscalar measure of a body's capacity to do work. There
are two types of energy: potential energy and kinetic energy. Energy cannot be created
or destroyed, but may be transformed from one form to another. This principle is called
conservation of energy. The equation for total energy is:
TE = PE + KE
Potential energy (PE) - answerthe ability of a body to do work because of its position or
state of being. It is a function of mass (m), gravity (g), and height (h):
PE = weight x height = mgh
Kinetic energy (KE) - answerthe ability of a body to do work because of its motion. It is a
function of mass (m) and velocity (V):
KE = 1⁄2 mV2
NEWTON'S FIRST LAW - THE LAW OF EQUILIBRIUM - answer"A body at rest tends
to remain at rest and a body in motion tends to remain in motion in a straight line at a
constant velocity unless acted upon by some unbalanced force."
Equilibrium - answerthe absence of acceleration, either linear or angular.
Equilibrium flight - answerexists when the sum of all forces and the sum of all moments
around the center of gravity are equal to zero. An airplane in straight and level flight at a
constant velocity is acted upon by four forces: thrust, drag, lift and weight. When these
forces exactly cancel each other out, the airplane is in equilibrium (Figure 1-3).
Trimmed flight - answerexists when the sum of all moments around the center of gravity
is equal to zero. In trimmed flight, the sum of the forces may not be equal to zero. For
example, an airplane in a constant rate, constant angle of bank turn is in trimmed, but
not equilibrium, flight. An airplane in equilibrium flight, however, is always in trimmed
flight.
NEWTON'S SECOND LAW - THE LAW OF ACCELERATION - answer"An unbalanced
force (F) acting on a body produces an acceleration (a) in the direction of the force that
is directly proportional to the force and inversely proportional to the mass (m) of the
body."
NEWTON'S THIRD LAW - THE LAW OF INTERACTION - answer"For every action,
there is an equal and opposite reaction; the forces of two bodies on each other are
always equal and are directed in opposite directions."
Static pressure (PS) - answeris the pressure particles of air exert on adjacent bodies.
Ambient static pressure is equal to the weight of a column of air over a given area. The
force of static pressure always acts perpendicular to any surface that the air particles
collide with, regardless of whether the air is moving with respect to that surface.
, Air density (ρ) - answeris the total mass of air particles per unit of volume. The distance
between individual air particles increases with altitude resulting in fewer particles per
unit volume. Therefore, air density decreases with an increase in altitude.
Temperature (T) - answeris a measure of the average random kinetic energy of air
particles.
average lapse rate - answerAir temperature decreases linearly with an increase in
altitude at a rate of 2 °C (3.57 °F) per 1000 ft until approximately 36,000 feet. This rate
of temperature change.
isothermal layer - answerFrom 36,000 feet through approximately 66,000 feet, the air
remains at a constant −56.5 °C (−69.7 °F). This layer of constant temperature.
Humidity - answeris the amount of water vapor in the air. As humidity increases, water
molecules displace an equal number of air molecules. Since water molecules have less
mass and do not change the number of particles per unit volume of air, density
decreases. Therefore, as humidity increases, air density decreases.
Viscosity (μ) - answera measure of the air's resistance to flow and shearing. Air
viscosity can be demonstrated by its tendency to stick to a surface. For liquids, as
temperature increases, viscosity decreases.
local speed of sound - answerthe rate at which sound waves travel through a particular
air mass. The speed of sound, in air, is dependent only on the temperature of the air.
The warmer the air, the more excited the particles are in that air mass. The more
excited the molecules are, the more easily adjacent molecules can propagate a sound
wave. As the temperature of air increases, the speed of sound increases.
standard atmosphere - answerset of reference conditions giving representative values
of air properties as a function of altitude
General Gas Law - answersets the relationship between three properties of air:
pressure (P), density (ρ), and temperature (T). It is expressed as an equation where R
is a constant for any given gas (such as dry air):
P = ρ RT
True altitude - answerthe actual height above mean sea level.
Pressure altitude (PA - answerthe height above the standard datum plane. The
standard datum plane is the actual elevation at which the barometric pressure is 29.92
inHg. Since the standard datum plane is at sea level in the standard atmosphere, true
altitude will be equal to pressure altitude.
Scalar - answer quantity that represents only magnitude, e.g., time, temperature, or
volume. It is expressed using a single number, including any units.
vector - answer quantity that represents magnitude and direction. It is commonly used
to represent displacement, velocity, acceleration, or force.
Displacement (s) - answerthe distance and direction of a body's movement (an airplane
flies east 100 nm).
Velocity (V) - answerthe speed and direction of a body's motion, the rate of change of
position (an airplane flies south at 400 knots).
Speed - answera scalar equal to the magnitude of the velocity vector.
Acceleration (a) - answerthe rate and direction of a body's change of velocity (gravity
accelerates bodies toward the center of the earth at 32.174 ft/s2).
force (F) - answera push or pull exerted on a body (1,000 lbs of thrust pushes a jet
through the sky).
Mass (m) - answerthe quantity of molecular material that comprises an
object.
Volume (v) - answerthe amount of space occupied by an object
Density (ρ) - answermass per unit volume. ρ = mass / volume
Weight (W) - answerthe force with which a mass is attracted toward the center of the
earth by gravity.
Force (F) - answermass times acceleration. F = mx a
moment (M) - answercreated when a force is applied at some distance from an axis or
fulcrum, and tends to produce rotation about that point.
Work (W) - answerdone when a force acts on a body and moves it. It is a scalar quantity
equal to the force (F) times the distance of displacement (s).
W=Fxs
Power (P) - answerhe rate of doing work or work done per unit of time.
P =W / t
,Energy - answerscalar measure of a body's capacity to do work. There
are two types of energy: potential energy and kinetic energy. Energy cannot be created
or destroyed, but may be transformed from one form to another. This principle is called
conservation of energy. The equation for total energy is:
TE = PE + KE
Potential energy (PE) - answerthe ability of a body to do work because of its position or
state of being. It is a function of mass (m), gravity (g), and height (h):
PE = weight x height = mgh
Kinetic energy (KE) - answerthe ability of a body to do work because of its motion. It is a
function of mass (m) and velocity (V):
KE = 1⁄2 mV2
NEWTON'S FIRST LAW - THE LAW OF EQUILIBRIUM - answer"A body at rest tends
to remain at rest and a body in motion tends to remain in motion in a straight line at a
constant velocity unless acted upon by some unbalanced force."
Equilibrium - answerthe absence of acceleration, either linear or angular.
Equilibrium flight - answerexists when the sum of all forces and the sum of all moments
around the center of gravity are equal to zero. An airplane in straight and level flight at a
constant velocity is acted upon by four forces: thrust, drag, lift and weight. When these
forces exactly cancel each other out, the airplane is in equilibrium (Figure 1-3).
Trimmed flight - answerexists when the sum of all moments around the center of gravity
is equal to zero. In trimmed flight, the sum of the forces may not be equal to zero. For
example, an airplane in a constant rate, constant angle of bank turn is in trimmed, but
not equilibrium, flight. An airplane in equilibrium flight, however, is always in trimmed
flight.
NEWTON'S SECOND LAW - THE LAW OF ACCELERATION - answer"An unbalanced
force (F) acting on a body produces an acceleration (a) in the direction of the force that
is directly proportional to the force and inversely proportional to the mass (m) of the
body."
NEWTON'S THIRD LAW - THE LAW OF INTERACTION - answer"For every action,
there is an equal and opposite reaction; the forces of two bodies on each other are
always equal and are directed in opposite directions."
Static pressure (PS) - answeris the pressure particles of air exert on adjacent bodies.
Ambient static pressure is equal to the weight of a column of air over a given area. The
force of static pressure always acts perpendicular to any surface that the air particles
collide with, regardless of whether the air is moving with respect to that surface.
, Air density (ρ) - answeris the total mass of air particles per unit of volume. The distance
between individual air particles increases with altitude resulting in fewer particles per
unit volume. Therefore, air density decreases with an increase in altitude.
Temperature (T) - answeris a measure of the average random kinetic energy of air
particles.
average lapse rate - answerAir temperature decreases linearly with an increase in
altitude at a rate of 2 °C (3.57 °F) per 1000 ft until approximately 36,000 feet. This rate
of temperature change.
isothermal layer - answerFrom 36,000 feet through approximately 66,000 feet, the air
remains at a constant −56.5 °C (−69.7 °F). This layer of constant temperature.
Humidity - answeris the amount of water vapor in the air. As humidity increases, water
molecules displace an equal number of air molecules. Since water molecules have less
mass and do not change the number of particles per unit volume of air, density
decreases. Therefore, as humidity increases, air density decreases.
Viscosity (μ) - answera measure of the air's resistance to flow and shearing. Air
viscosity can be demonstrated by its tendency to stick to a surface. For liquids, as
temperature increases, viscosity decreases.
local speed of sound - answerthe rate at which sound waves travel through a particular
air mass. The speed of sound, in air, is dependent only on the temperature of the air.
The warmer the air, the more excited the particles are in that air mass. The more
excited the molecules are, the more easily adjacent molecules can propagate a sound
wave. As the temperature of air increases, the speed of sound increases.
standard atmosphere - answerset of reference conditions giving representative values
of air properties as a function of altitude
General Gas Law - answersets the relationship between three properties of air:
pressure (P), density (ρ), and temperature (T). It is expressed as an equation where R
is a constant for any given gas (such as dry air):
P = ρ RT
True altitude - answerthe actual height above mean sea level.
Pressure altitude (PA - answerthe height above the standard datum plane. The
standard datum plane is the actual elevation at which the barometric pressure is 29.92
inHg. Since the standard datum plane is at sea level in the standard atmosphere, true
altitude will be equal to pressure altitude.
