test 2.0

Question 1

For heating a home, does electrical-resistance baseboard
heating or a heat pump use less electricity? Explain.

Answer 1

Question 2

For a control volume at steady state, mass can accumulate
within the control volume.

Answer 2

Question 3

Flow work is the work done on a flowing stream by a
paddle wheel or piston.

Answer 3

Question 4

An open feedwater heater is a special type of a counterflow
heat exchanger.

Answer 4

Question 5

Answer 5

Question 6

An internal irreversibility within a gearbox is (a) chemical
reaction, (b) unrestrained expansion of a gas, (c) mixing, (d)
friction.

Answer 6

Question 7

Answer 7

Question 8

Referring to the list of Sec. 5.3.1, significant irreversibilities
present during operation of a household refrigerator include
(a) inelastic deformation, (b) chemical reaction, (c) heat transfer
through a finite temperature difference, (d) none of the above.

Answer 8

Question 9

As velocity decreases in a diffuser, pressure decreases.

Answer 9

Question 10

The maximum thermal efficiency of any power cycle
operating between hot and cold thermal reservoirs at 10008C
and 5008C, respectively, is 50%.

Answer 10

Question 11

what is a property

Answer 11

a quantity is a property if, and only if, its change in value between two states is independent of the process linking the two states, we conclude that the integral represents the change in some property of the system

Question 12

Where mass crosses the boundary of a control volume, the
accompanying energy transfer is accounted for by the
internal energy of the mass only.

Answer 12

Question 13

A significant increase in pressure can be achieved by
introducing a restriction into a line through which a gas or
liquid flows.

Answer 13

Question 14

entropy applies to any process between states

Answer 14

since entropy is a property, that value of entropy change applies to any process between the states – internally reversible or not

Question 15

A cell phone initially has a fully charged battery. After a
period of cell phone use, the battery is recharged to its initial
state. The quantity of electricity to recharge the battery is
(a) less than, (b) equal to, (c) greater than the quantity
required to operate the phone. Explain.

Answer 15

Question 16

The hot and cold streams of cross-flow heat exchangers
flow in the same direction.

Answer 16

Question 17

When an isolated system undergoes a process, the values
of its energy and entropy can only increase or remain the
same.

Answer 17

Question 18

A _____________ is a device that introduces a restriction
into a line to reduce the pressure of a gas or liquid.

Answer 18

Question 19

The Clausius statement of the second law denies the
possibility of transferring energy by heat from a cooler to a
hotter body.

Answer 19

Question 20

Answer 20

Question 21

In this book the flow at control volume inlets and exits is
normally taken as one-dimensional.

Answer 21

Question 22

An ideal gas in a piston-cylinder assembly expands
isothermally, doing work and receiving an equivalent amount
of energy by heat transfer from the surrounding atmosphere.
Is this process of the gas in violation of the Kelvin–Planck
statement of the second law? Explain.

Answer 22

Question 23

System integration is the practice of combining components
to achieve an overall objective.

Answer 23

Question 24

Answer 24

Question 25

Referring to the list of Sec. 5.3.1, irreversibilities present during operation of an internal combustion automobile engine include (a) friction, (b) heat transfer, (c) chemical reaction, (d) all of the above.

Answer 25

Question 26

Answer 26

Question 27

There are no irreversibilities within a system undergoing an internally reversible process.

Answer 27

Question 28

Uses of the second law of thermodynamics include (a) defining the Kelvin scale, (b) predicting the direction of processes, (c) developing means for evaluating internal energy in terms of more readily measured properties, (d) all of the above.

Answer 28

Question 29

\_\_\_\_\_\_\_\_\_\_\_\_\_ operation involves state changes with time.

Answer 29

Question 30

Transient operation denotes a change in state with time.

Answer 30

Question 31

The maximum coefficient of performance of any refrigeration cycle operating between cold and hot reservoirs at 408F and 808F, respectively, is closely 12.5.

Answer 31

Question 32

When a substance undergoes a throttling process through a valve, the specific enthalpies of the substance at the valve inlet and valve exit are equal.

Answer 32

Question 33

Mass, energy, entropy, and temperature are examples of extensive properties.

Answer 33

Question 34

The second Carnot corollary states that all power cycles operating between the same two thermal reservoirs have the same thermal efficiency.

Answer 34

Question 35

Answer 35

Question 36

Mass flow rate for a flow modeled as one-dimensional depends on all except (a) Density of working fluid (b) Cross-sectional area through which flow passes (c) Velocity of working fluid (d) Total volume of working fluid

Answer 36

Question 37

For a closed system, entropy (a) may be produced within the system, (b) may be transferred across its boundary, (c) may remain constant throughout the system, (d) all of the above.

Answer 37

Question 38

entropy is what type of property

Answer 38

extensive

Question 39

A mixing chamber is a direct-contact heat exchanger.

Answer 39

Question 40

A throttling process is (a) reversible, (b) internally reversible, (c) irreversible, (d) isobaric.

Answer 40

Question 41

Answer 41

Question 42

For every control volume at steady state, the total of the entering rates of mass flow equals the total of the exiting rates of mass flow.

Answer 42

Question 43

At steady state, conservation of energy asserts the total rate at which energy is transferred into the control volume equals the total rate at which energy is transferred out.

Answer 43

Question 44

When hot and cold gas streams pass in counterflow through a heat exchanger, each at constant pressure, the principal internal irreversibility for the heat exchanger is \_\_\_\_\_\_\_\_\_\_.

Answer 44

Question 45

Answer 45

Question 46

Internally reversible processes do not actually occur but serve as hypothetical limiting cases as internal irreversibilities are reduced further and further.

Answer 46

Question 47

what is the equation for entropy

Answer 47

Question 48

Hydropower is a nonrenewable means for producing electricity.

Answer 48

Question 49

A key step in thermodynamic analysis is the careful listing of modeling assumptions.

Answer 49

Question 50

At steady state, conservation of mass asserts the total rate at which mass enters the control volume equals the total rate at which mass exits.

Answer 50

Question 51

Every process consistent with the conservation of energy and conservation of mass principles can actually occur in nature.

Answer 51

Question 52

When left alone, systems tend to undergo spontaneous changes until equilibrium is attained, both internally and with their surroundings.

Answer 52

Question 53

At steady state, identical electric fans discharging air at the same temperature in New York City and Denver will deliver the same volumetric flow rate of air.

Answer 53

Question 54

Answer 54

Question 55

The time rate of mass flow per unit area is called (a) Mass flow rate (b) Volumetric flow rate (c) Velocity (d) Mass flux

Answer 55

d.) mass flux

Question 56

Answer 56

Question 57

For a one-inlet, one-exit control volume at steady state, the mass flow rates at the inlet and exit are equal but the inlet and exit volumetric flow rates may not be equal..

Answer 57

Question 58

A process of a closed system that violates the second law of thermodynamics necessarily violates the first law of thermodynamics.

Answer 58

Question 59

Compressor types include reciprocating, axial flow, centrifugal, and Roots type.

Answer 59

Question 60

The Carnot efficiency also limits the efficiency of wind turbines in generating electricity.

Answer 60

Question 61

In principle, the Clausius inequality applies to any cycle.

Answer 61

Question 62

Answer 62

Question 63

Common heat exchanger types include direct-contact, counterflow, parallel-flow, and cross-flow heat exchangers.

Answer 63

Question 64

Volumetric flow rate is expressed in units of m3/s or ft3/s.

Answer 64

Question 65

The coefficient of performance of a reversible refrigeration cycle is always (a) greater than, (b) less than, (c) equal to the coefficient of performance of an irreversible refrigeration cycle when each operates between the same two thermal reservoirs.

Answer 65

Question 66

Answer 66

Question 67

An automobile’s radiator is an example of a cross-flow heat exchanger.

Answer 67

Question 68

Just as mass and energy are accounted for by mass and energy balances, entropy is accounted for by an entropy balance

Answer 68

True

Question 69

The mechanisms of energy transfer for a control volume are \_\_\_\_\_\_\_\_\_\_\_\_\_, \_\_\_\_\_\_\_\_\_\_\_\_\_, and \_\_\_\_\_\_\_\_\_\_\_\_\_.

Answer 69

Question 70

A diffuser is a flow passage of varying cross-sectional area in which the velocity of a gas or liquid increases in the direction of flow.

Answer 70

Question 71

Entropy can be transferred across a system boundary

Answer 71

True, Like mass and energy, entropy can be transferred across the system boundary

Question 72

The entropy change and entropy balance concepts are developed using the \_\_\_\_\_\_\_\_\_

Answer 72

clausius inequality

Question 73

The human body is an example of an integrated system.

Answer 73

Question 74

The change in entropy of a closed system is the same for every process between two specified end states.

Answer 74

Question 75

Answer 75

Question 76

what is enthalpy-entropy called

Answer 76

mollier diagram

Question 77

One statement of the second law of thermodynamics recognizes that the extensive property entropy is produced within systems whenever internal irreversibilities are present.

Answer 77

Question 78

what is the equation for entropy using the saturated states

Answer 78

Question 79

Answer 79

Question 80

The coefficient of performance of an irreversible heat pump cycle is always (a) equal to, (b) greater than, (c) less than the coefficient of performance of a reversible heat pump cycle when each operates between the same two thermal reservoirs.

Answer 80

Question 81

For one-dimensional flow, mass flow rate is the product of density, area, and velocity.

Answer 81

Question 82

When placed outside and exposed to the atmosphere, an ice cube melts, forming a thin film of liquid on the ground. Overnight, the liquid freezes, returning to the initial temperature of the ice cube. The water making up the cube undergoes (a) a thermodynamic cycle, (b) a reversible process, (c) an irreversible process, (d) none of the above.

Answer 82

Question 83

The thermodynamic performance of a device such as a turbine through which mass flows is best analyzed by studying the flowing mass alone.

Answer 83

Question 84

Referring to the list of Sec. 5.3.1, irreversibilities present during operation of a forced-air, natural gas-fueled furnace include all of the following except (a) chemical reaction, (b) fluid friction, (c) polarization, (d) heat transfer.

Answer 84

Question 85

As velocity increases in a nozzle, pressure \_\_\_\_\_\_\_\_\_\_\_\_\_.

Answer 85

decreases

Question 86

Friction associated with flow of fluids through pipes and around objects is one type of irreversibility.

Answer 86