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What does Newton's first law of motion state?
A body at rest remains at rest, a body in motion continues to move in a constant speed in a straight line unless acted on by an external force
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Newton's first law of motion is also considered the definition of what term?
Inertia
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What is Newton's second law of motion?
An unbalanced force on a body produces or tends to produce an acceleration in the direction of the force and that the acceleration, if any, is directly proportional to the force and inversely proportional to the mass of the body.
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Which law of Newton's laws best explains why a jet engine produces forward thrust?
Newton's third law of motion
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What two words can best sum up Newton's third law of motion?
Action and reaction
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What does Bernoulli's principle state?
When the speed of a stream of gas increases, the pressure of the gas decreses, and when the speed of the gas decreases, the pressure increases
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What type of duct is used to decrease pressure and increase velocity?
convergent duct
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how does the design of an airfoil influence pressure above and below the airfoil to produce life?
decreasing air pressure above airfoil and increasing pressure below creates lift
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Ability to do work. . .
Energy
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A force moves an object
Work
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The tendency of an object to maintain its direction or speed
Inertia
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Sometimes thought of as a physical effort
Work
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Commonly expressed as Btu's
heat
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Reduced by using lubricants
friction
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Equals force times distance
Work
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Kinetic and potential
Energy
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A type of energy that results from molecular motion
heat
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What type of energy does a falling object possess?
Kinetic
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Can energy pass from potential to kinetic and back to potential?
yes
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Which jet engine section produces the large volumes of air required for the production of thrust?
compressor
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What does the combustion section do to support the production of thrust?
Introduces fuel and burns it in the air stream behind the compressor. Burning the fuel increases the air temperature and expands the air
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What is the energy that is expended through the exhaust nozzle used for
thrust to propel the aircraft forward
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What is used to create the propulsive force for a turboprop engine
propeller
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which terms are used to express the thrust produced by a T56 engine?
horsepower and pounds of torque
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which term is used to define the theoretical power of a frictionless engine?
Indicated horsepower
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what is friction horsepower
indicated horsepower minus brake horsepower
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which type of horsepower determines the performance of the engine-propeller combination?
equivalent shaft horsepower (aka thrust horsepower)
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what can you determine if you know the Btu content of a gallon of fuel and how much the gallon of fuel weighs?
the potential horsepower of the fuel
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what type of fuel do today's jet engines use?
JP-8
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The thermal efficiency of a jet engine is equal to what?
the energy produced by the engine, divided by the energy of the fuel consumed by the engine
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What two factors determine what proportion of the engergy of a fuel is actually used to propel an aircraft forward?
thermal and propulsive efficiency
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Define the term barometric pressure
the force exerted by the mass of a column of air above the point where the pressure is being measured
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what instrument is used to measure barometric pressure
a barometer
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why is a measurement of 14.7 psi sometimes referred to as a standard day atmopheric condition?
because if the mercury in a column 1 square inch by 29.92 inches high were weighed, it would weigh 14.7 lbs.
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why was a US standard day condition developed
because some standard was necessary as a reference point for computing and calculating purposes
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what two factors tend to cause variations in the temperature of the atmosphere?
altitude and latitude
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Define the term density, as it applies to air
material mass per unit volume
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list the three methods by which heat can be transferred
- radiation
- convection
- conduction
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where is the point of highest pressure within a jet engine?
diffuser
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on a jet engine that does not have an afterburner, where is the point of highest temperature
combustion section
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when a jet engine reaches idle speed, what determines how the fuel control regulates engine speed?
power lever setting
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what two forms of energy does a jet engine produce?
thrust and heat
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approximately what percent of the energy produced by the fuel is needed to maint. the jet engine operating cycle?
60
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why does the airflow velocity of the exhaust gases increase within the turbine stator?
because the size of the openings through which the gases flow is reduced
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where is the point of highest airflow velocity in a jet engine?
at the ejector nozzle
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what compnent directs the gases that strike the turbine wheel blades?
turbine stator
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what is the purpose of the turbine stator?
to increase velocity of the gases striking the turbine blades
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after the gases leave the turbine section and enter the exhaust section, what type of velocity do they have?
axial
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what straightens the flowpath of gases in the exhaust case?
the vanes in the exhaust case
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in a multistge turbine, what is the arrangement of the shafts?
one shaft is hollow, allowing the other shaft to operate inside it
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which turbine drives the front compressor on a dual-spool engine
the rear turbine
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what is a turbojet engine?
an air-dependent, thermal, jet propulsion device
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name the three main sections of a gas turbine engine
compressor, burner, turbine
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today's jet engine compressors are an outgrowth of what units that are normally used with reciprocating engines
the turbo-supercharger
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what requirement must exist for the successful operation of either jet or reciprocating engines?
the engines must be able to handle large amounts of air in a short period of time
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how do pressure pulsations in a centrifugal compressor appear?
as shock waves or irregular movement of air through the compressor
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