Lecture 2 - Terminology & Equations

Question 1

The first law of thermodynamics is also known as …

Answer 1

the conservation of energy law.

Question 2

Thermodynamics is a science that deals with _______.

Answer 2

energy

Question 3

The first law of thermodynamics for a closed system as an equation is __________, where ___________, and the units are in ___________.

Answer 3

Q – W = ∆E (for a closed system)
Q = heat transfer
W = Work
∆E = change in energy

Joules

Question 4

Heat flow into a system is considered _______.

Answer 4

Positive

Question 5

Heat flow out of a system is considered _______.

Answer 5

Negative

Question 6

Work done by the system is considered _________.

Answer 6

positive

Question 7

Work done on a system is considered _________.

Answer 7

negative

Question 8

∆E is the sum of _________, where ___________.

Answer 8

∆U, ∆KE, and ∆PE
where ∆U is the change in internal energy of the matter of the system we are considering
∆KE is the change in kinetic energy, which is the macroscopic motion of the system
∆PE is the change in potential energy, which is the change in height of the system

Question 9

∆U is the change in ____________ of the matter of the system we are considering in the form of __________, __________, or _____________ for a solid.

Answer 9

internal energy
molecular motion
lattice vibration
electron motion

Question 10

∆KE is the ____________, which is like _________, even though it is the molecules themselves that are moving around.

Answer 10

macroscopic motion of the system

a big chunk of a system that moves together at the same velocity

Question 11

∆PE is _____________ or the change in height of a system.

Answer 11

the change in elevation with respect to some reference frame.

Question 12

∆E = ___ + _____+ ________ [_]

Answer 12

∆U + ∆KE + ∆PE [J]

Question 13

The second law of thermodynamics helps us …

Answer 13

helps us figure out which direction the energy is flowing within a system

Question 14

The second law of thermodynamics ______________ in which a __________ and __________ is.

Answer 14

determines the direction

how efficiently that process

Question 15

The two types of systems in thermodynamics are _______ and ___________.

Answer 15

open system

closed system

Question 16

A closed system is also called a _____________ because ______________.

Answer 16

fixed mass system

mass can’t cross the boundary of the system

Question 17

A closed system can be defined as _____________.

Answer 17

A system of fixed mass

Question 18

A piston (pistón o émbolo) cylinder device with a load on top and a gas within the cylinder with a _________ boundary ___________ of the cylinder is an example of a ______________ system.

Answer 18

checkered line
along the lines
closed system

Question 19

In a closed system, everything ____________ is the surroundings

Answer 19

outside the system

Question 20

In a closed system, the few things that can cross the system boundary are found in _____________ and are _____ and ___________.

Answer 20

the first law of thermodynamics
heat
work

Question 21

In a closed system, ___________ and ______________ both move _____________.

Answer 21

heat
work
into and out of the system

Question 22

A propeller (hélice o propulsor) rotating in a cylinder with a load on top is an example of a ___________, and the propeller produces ____________, which _____________ inside the cylinder.

Answer 22

closed system
shaft work
heats up the gas

Question 23

In the process of heating up a gas, we are doing ______.

Answer 23

work

Question 24

In a closed system, work and heat cross the system boundary but mass can’t, which is why a closed system is a fixed mass system.

Answer 24

True

Question 25

In an open system, ______________.

Answer 25

mass can cross the boundary of a system

Question 26

An open system can be described as ______________.

Answer 26

a system that involves mass transfer across its boundary

Question 27

A turbine (turbina), compressor (compresor), or pump (bomba, surtidor, pompa) are examples of an _____________ system.

Answer 27

open

Question 28

Piston in spanish

Answer 28

pistón o émbolo

Question 29

Turbine in spanish

Answer 29

turbina

Question 30

Compressor in spanish

Answer 30

compresor

Question 31

Pump in spanish

Answer 31

bomba, surtidor o pompa

Question 32

Pump in spanish

Answer 32

bomba, surtidor o pompa

Question 33

Jet in spanish

Answer 33

surtidor

Question 34

The boundary of an open system is called ____________ because ____________.

Answer 34

the control surface | mass can cross the boundary

Question 35

Within the control surface, we have ___________.

Answer 35

a control volume

Question 36

In an open system, ____________.

Answer 36

mass flows in and out

Question 37

When doing an analysis of an open system, we have to describe __________________.

Answer 37

the conditions of the fluid moving into and out of the system.

Question 38

In an open system, we describe the _______, ____________, and ___________ going into a system.

Answer 38

pressure, P1 temperature, T1 velocity, v1

Question 39

In an open system, we describe the ____, ________, ___________ leaving the system.

Answer 39

pressure, P2 temperature, T2 velocity, v2

Question 40

Q and W flow ___________ a control surface.

Answer 40

across

Question 41

Ẇ is the __________ in __________ or ______.

Answer 41

rate of work produced [J/s] [W]

Question 42

Q̇ is the ___________ in __________ or _________.

Answer 42

rate of heat transfer per unit time [J/s] [W]

Question 43

Properties describe the state of a system.

Answer 43

True

Question 44

The three types of properties are __________.

Answer 44

extensive intensive specific

Question 45

Extensive properties are __________, and all the symbols are _____________, except for _________. Examples are ____________.

Answer 45

dependent on the mass or size of the system all in capital letters mass mass (m), volume (V), and total energy (E)

Question 46

Intensive properties are _____________. Examples are __________.

Answer 46

not dependent on the size of the system | temperature (T), and pressure (P)

Question 47

Specific properties are _____________, and their symbols are ______. For example _____________.

Answer 47

extensive properties per unit mass in small letters specific volume (v), specific total energy (e), and specific internal energy (u)

Question 48

u = e = v =

Answer 48

U/m E/m V/m

Question 49

In thermodynamics, the letter "v" smybolizes

Answer 49

volume

Question 50

A __________ describes the state of a system.

Answer 50

property

Question 51

A _________ is described by its properties.

Answer 51

system

Question 52

Properties are _____________ to which __________ without ____________.

Answer 52

macroscopic characteristics numerical values are assigned previous knowledge of the history of the system

Question 53

The origins of properties are _____________, like _____________, ________________ , like entropy, or ___________, like enthalpy.

Answer 53

1. directly measured, like pressure and temperature 2. Defined by the laws of thermodynamics 3. defined by mathematical combinations

Question 54

Enthalpy = (U+P)*v

Answer 54

True

Question 55

The state of a system, is a description of _________________ from a small subset of __________.

Answer 55

the condition of the system at a given instant | independent property values

Question 56

From a number of property values, we can specify the state in which a system currently is.

Answer 56

True

Question 57

Once we have specified the state of the system from ____________, usually ____, all other properties properties ___________ or determined from the subset.

Answer 57

a small number of independent property values 2 have been defined

Question 58

Equilibrium in thermodynamic systems are described as ______________.

Answer 58

being in a state of equilibrium

Question 59

Properties are only defined when ______________, so no unbalanced potentials or __________ are within the system.

Answer 59

they are in a state of equilibrium | driving forces

Question 60

For a system in equilibrium, there is no temperature or pressure difference.

Answer 60

True

Question 61

A process is _____________.

Answer 61

the transformation of a system from 1 state to another

Question 62

End states are the beginning and final state of a process.

Answer 62

True

Question 63

We use a process diagram to know where we are within different properties or states.

Answer 63

True

Question 64

A dot or circle with a number next to it in a process diagram represents the _________.

Answer 64

end state

Question 65

In a process diagram, we include _______.

Answer 65

1. the end states 2. the direction of the process, indicated by an arrow 3. the process path

Question 66

The direction of a process is indicated by an arrow.

Answer 66

True

Question 67

The process path is the line connecting two end points.

Answer 67

True

Question 68

A complete description of a process requires:

Answer 68

1. specification of the end states 2. the process path 3. the interactions across the boundaries

Question 69

The process path tells us which way a process is going and which properties it goes through from 1 end point to another.

Answer 69

True

Question 70

Examples of the interactions across the system boundaries are ______________.

Answer 70

heat, work, and mass (in an open system)

Question 71

When a system undergoes a change of state, the change ______________ does not depend on the process connecting two end states.

Answer 71

in the value of the properties

Question 72

When a system undergoes a change of state, the change in the value of the properties does not depend on the process connecting two end states. This means that ___________.

Answer 72

going through any state path, the pressure or volume won't change, for example, but the work, heat, or mass (if in an open system) will.

Question 73

When a system undergoes a change of state, the change in value of a property ____________.

Answer 73

does not depend on the process connecting the two end states

Question 74

If we have a value that does depend on the process path between two end states, _____________.

Answer 74

that quantity is not a property

Question 75

If the value of a quantity depends on the nature of the process between the two end states, that quantity is not a property. For example, _______________.

Answer 75

heat, work, and mass

Question 76

Cycles are _____________ (path has the same end state).

Answer 76

A process where the process path has identical end states

Question 77

Systems that we study are not really in equilibrium, so we make an approximation in the modelling of the system.

Answer 77

True

Question 78

A quasi-equilibrium process ___________

Answer 78

assumes that the system remains close to its equilibrium state during the process.

Question 79

Quasi - equilibrium is an ___________ because very few real processes are in quasi-equilibrium.

Answer 79

idealization

Question 80

Quasi-equilibrium process is the standard with which we compare real world processes.

Answer 80

True

Question 81

Work-producing devices produce maximum work in the quasi-equilibrium state, and real world systems are a little under the quasi-equilibrium state.

Answer 81

True