Aero/Thermo Final True-False
A compressed liquid state is characterized by lower pressures than its saturation pressure for a given temperature, such that P < Psat at a given T
False
A compressor is a work producing device while a turbine is a work consuming device
False
A control volume must be contained within the physical boundaries of a system
False
A neutrally bouyant zero-pressure balloon system, when exposed to sunlight, achieves lift because the pressure within the balloon increases
False
A pressure cooker containing water increases the pressure in the cooker to 2 atm. The temperature at which water boils must then decrease.
False
A thermodynamic power cycle is a sequence of processes whose work cycle exceeds the heat transfer cycle.
False
A unit for the product of pressure and specific volume is kJ
False
An adiabatic process refers to a process for which the temperature remains constant, thus there is no heat transfer.
False
An isobaric process is one in which the temperature remains constant
False
At steady flow and for a single exit and single inlet, the volumetric flow rate at the exit and the inlet must be equal
False
At steady state and for a single exit and single inlet, the mass flow rate at the exit equals the mass flow rate at the inlet. Therefore, the volumetric flow rate at the exit and the inlet must be equal.
False
For a steady-flow process, the mass within the control volume does not change with time because there is no mass flow rate.
False
For an ideal gas undergoing a polytropic process, the exponent (n) having a value equal to the specific heat ratio corresponds to an isothermal process.
False
For an ideal gas, the value of cp is always greater than cv and this difference is the universal gas constant
False
Heat transfer INTO the system is considered positive. An adiabatic process is only when heat is transferred OUT of the system.
False
In the liquid-vapor mixture region a state for a simple compressible system can be specified by the two properties of pressure and temperature.
False
In the liquid-vapor mixture region, a state for a simple compressible system can be specified by (P,T).
False
It takes more energy to raise the temperature of 1kg of air by 1K than it does to raise the temperature of 1kg of water by 1K
False
Neither mass nor energy may cross the boundary of a closed system. Both mass and energy may cross the boundary of an open system.
False
Positive values of pressure coefficient Cp indicate velocities higher than the free-stream value, whereas negative values indicate velocities lower than the free-steam value
False
Power accounts for the time rate of energy change due to work. Therefore, the SI units are Joules.
False
Specific heat is not a property and therefore depends on the process.
False
The 10 ms^-1 flow around a body with overall scale L=10m is dynamically similar to the 100ms^-1 flow around a body with overall scale L=100m
False
The Kelvin and Rankine temperature scales are thermodynamic temperature scales and the Celsius and Fahrenheit scales two-point scales. Since the Kelvin and Rankine scales start at absolute zero, the magnitude of a unit kelvin (K) is identical to a unit rankine (°R).
False
The Reynolds number is defined as UL/v where v is the dynamic viscosity. The units of dynamic viscosity are kgm^-2s^-1.
False
The derivation of Euler's equation assumes the density to be constant
False
The enthalpy change of a fluid is often much less than the change in kinetic energy of the fluid when passing through a pump operating at a steady flow
False
The first law of thermodynamics is concerned with the net change of the total energy deltaE of the system and the total energy is an intensive property
False
The mass flow rate is independent of the fluid density
False
The relation deltah=m(cp)(deltat) is applicable to systems only undergoing a constant-pressure process
False
The saturated liquid-vapor mixture state is a two-phase state where the substance as a liquid and a vapor co-exist in equilibrium. This two-phase state for a simple compressible system can be specified given P,T.
False
The value of cp is greater than cv for an ideal gas with the difference being the universal gas constant.
False
Energy transport by mass entering and leaving the system is zero for closed systems
True
For a control volume at steady state every property is independent of time.
True
For a polytropic process to be isothermal, pressure and volume must be inversely proportional to each other
True
For a simple compressible system, only two independent intensive properties are needed to describe the system.
True
For a steady flow process all intensive and extensive properties do not change with time
True
For a steady flow system, boundary work is zero
True
For an ideal gas, the difference between cp and cv is the specific gas constant
True
For and ideal gas, internal energy and enthalpy can be determined given only the temperature
True
For nozzles and diffusers the only work is flow work.
True
For the steady state devices analyzed, the potential energy change and the kinetic energy change are relatively small compared to the change in enthalpy, so these terms can usually be ignored.
True
Heat is transferred by only three mechanisms: conduction, convection and radiation
True
In control volumes, the conservation of energy equation is often expressed as a rate equation due to the need to account for the rates of energy transfer by the entering and exiting streams
True
The total energy of a system can be determined by the summation of internal, kinetic, and potential energies of the system, with a change in the total energy of a stationary system equal to its change in internal energy
True
The triple point on a P-T phase diagram is actually a line that can be illustrated in a P-v-T diagram.
True
Work can be generally considered as energy transfer associated with a force acting through a distance
True
The temperature of the air rises as it is compressed by an adiabatic compressor
True
The total energy of a flowing fluid must account for flow energy
True
To describe a system requires a definition of its boundary, knowledge of its properties and how they are related. Intensive properties are those that are dependent on the size of the system. Extensive properties are those whose values are independent of the size—or extent—of the system.
False
To describe a system requires a definition of its boundary, knowledge of its properties and how they are related. Intensive properties are those that are dependent on the size of the system. Extensive properties are those whose values are independent of the system size.
False
Work and heat transfer are properties of the system. Therefore work and heat are independent of the process path.
False
A cambered airfoil can produce lift even when the angle of attack is zero
True
A factor of safety is the ratio of the failure-producing value to the actual value and should always be greater than one to be successful.
True
A fan is a form of compressor increasing the pressure slightly while also mobilizing the gas
True
A nozzle increases the velocity of a fluid at the expense of pressure
True
A process must be both adiabatic and reversible in order to be isentropic. For the process to be reversible, it must be free of friction or any other kind of dissipation
True
A quasi-equilibrium process is one that in passing through states the departure from thermodynamic equilibrium is infinitesimal
True
A set of properties that completely describes the condition of a system describes its state. A change in state indicates that a process has occurred.
True
A set of properties that completely describes the condition of a system describes its state. A system is said to be in steady state if none of its properties changes with time.
True
A system is said to have gone through a thermodynamic cycle if it returns to its initial state at the end of a process
True
A system with a quality value, x=1, is in a saturated vapor state
True
Air France Flight 447, a modern commercial jetliner, crashed into the ocean on June 1, 2009, because the pilot kept the angle of attack so high that loss of lift persisted for an extended period of time.
True
An adiabatic process is one in which heat transfer is zero
True
At steady state and for a single exit and single inlet, the mass flow rate at the exit equals the mass flow rate at the inlet. If the incompressible model is imposed, the volumetric flow rate at the exit and the inlet must be equal.
True
Classical thermodynamics takes a macroscopic approach that does not require knowledge of the behavior of individual particles
True
Devices that transfer energy between fluids at different temperatures by heat transfer modes are called heat exchangers.
True
During a thermodynamic cycle, the change in energy can be nonzero but there is no net change in energy upon completing the cycle.
True
During the process of vaporization, energy is absorbed by the system
True
In moist air (air containing water) water can condense to a liquid at typical temperatures while air components remain gaseous. Since the composition of liquid water (H2O) is different from the composition of gaseous air (N2, O2, ...), then moist air is not a pure substance.
True
Lift is proportional to the square of the speed, which is why planes need to pick up runway speed to take off
True
Mechanical energy is that portion of total energy that accounts for only the kinetic and potential energy of a flowing fluid
True
Sir George Cayley was the first to advance the concept that included a fixed wing for generating lift, and another separate mechanism for propulsion. This was one breakthrough that eventually made human flight possible
True
Specific enthalpy is an intensive property that equals the specific internal energy plus the product of pressure and specific volume
True
The SI metric system requires the use of various constants to describe relationships between units representing length, for example.
True
The Wright brothers used wing warping to roll their aircraft. Ailerons serve the same purpose on modern aircraft.
True
The compressibility factor Z exceeding a value of 1 accounts for the deviation from ideal-gas behavior.
True
The conservation of energy principle states that during an interaction, energy can change from one form to another but the total amount of energy remains constant
True
The ideal gas model helps to reduce the number of independent intensive variables for a simple compressible system from two to one for internal energy and enthalpy
True
The mass and energy content of the control volume remain constant during a steady-flow process
True
The only two forms of energy interactions associated with a closed system are heat transfer and work
True
