Lecture 2 - Terminology & Equations Flashcards
The first law of thermodynamics is also known as …
the conservation of energy law.
Thermodynamics is a science that deals with _______.
energy
The first law of thermodynamics for a closed system as an equation is __________, where ___________, and the units are in ___________.
Q – W = ∆E (for a closed system)
Q = heat transfer
W = Work
∆E = change in energy
Joules
Heat flow into a system is considered _______.
Positive
Heat flow out of a system is considered _______.
Negative
Work done by the system is considered _________.
positive
Work done on a system is considered _________.
negative
∆E is the sum of _________, where ___________.
∆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
∆U is the change in ____________ of the matter of the system we are considering in the form of __________, __________, or _____________ for a solid.
internal energy
molecular motion
lattice vibration
electron motion
∆KE is the ____________, which is like _________, even though it is the molecules themselves that are moving around.
macroscopic motion of the system
a big chunk of a system that moves together at the same velocity
∆PE is _____________ or the change in height of a system.
the change in elevation with respect to some reference frame.
∆E = ___ + _____+ ________ [_]
∆U + ∆KE + ∆PE [J]
The second law of thermodynamics helps us …
helps us figure out which direction the energy is flowing within a system
The second law of thermodynamics ______________ in which a __________ and __________ is.
determines the direction
how efficiently that process
The two types of systems in thermodynamics are _______ and ___________.
open system
closed system
A closed system is also called a _____________ because ______________.
fixed mass system
mass can’t cross the boundary of the system
A closed system can be defined as _____________.
A system of fixed mass
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.
checkered line
along the lines
closed system
In a closed system, everything ____________ is the surroundings
outside the system
In a closed system, the few things that can cross the system boundary are found in _____________ and are _____ and ___________.
the first law of thermodynamics
heat
work
In a closed system, ___________ and ______________ both move _____________.
heat
work
into and out of the system
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.
closed system
shaft work
heats up the gas
In the process of heating up a gas, we are doing ______.
work
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.
True
In an open system, ______________.
mass can cross the boundary of a system
An open system can be described as ______________.
a system that involves mass transfer across its boundary
A turbine (turbina), compressor (compresor), or pump (bomba, surtidor, pompa) are examples of an _____________ system.
open
Piston in spanish
pistón o émbolo
Turbine in spanish
turbina
Compressor in spanish
compresor
Pump in spanish
bomba, surtidor o pompa
Pump in spanish
bomba, surtidor o pompa
Jet in spanish
surtidor
The boundary of an open system is called ____________ because ____________.
the control surface
mass can cross the boundary
Within the control surface, we have ___________.
a control volume
In an open system, ____________.
mass flows in and out
When doing an analysis of an open system, we have to describe __________________.
the conditions of the fluid moving into and out of the system.
In an open system, we describe the _______, ____________, and ___________ going into a system.
pressure, P1
temperature, T1
velocity, v1
In an open system, we describe the ____, ________, ___________ leaving the system.
pressure, P2
temperature, T2
velocity, v2
Q and W flow ___________ a control surface.
across
Ẇ is the __________ in __________ or ______.
rate of work produced
[J/s]
[W]
Q̇ is the ___________ in __________ or _________.
rate of heat transfer per unit time
[J/s]
[W]
Properties describe the state of a system.
True
The three types of properties are __________.
extensive
intensive
specific
Extensive properties are __________, and all the symbols are _____________, except for _________. Examples are ____________.
dependent on the mass or size of the system
all in capital letters
mass
mass (m), volume (V), and total energy (E)
Intensive properties are _____________. Examples are __________.
not dependent on the size of the system
temperature (T), and pressure (P)
Specific properties are _____________, and their symbols are ______. For example _____________.
extensive properties per unit mass
in small letters
specific volume (v), specific total energy (e), and specific internal energy (u)
u =
e =
v =
U/m
E/m
V/m
In thermodynamics, the letter “v” smybolizes
volume
A __________ describes the state of a system.
property
A _________ is described by its properties.
system
Properties are _____________ to which __________ without ____________.
macroscopic characteristics
numerical values are assigned
previous knowledge of the history of the system
The origins of properties are _____________, like _____________, ________________ , like entropy, or ___________, like enthalpy.
- directly measured, like pressure and temperature
- Defined by the laws of thermodynamics
- defined by mathematical combinations
Enthalpy = (U+P)*v
True
The state of a system, is a description of _________________ from a small subset of __________.
the condition of the system at a given instant
independent property values
From a number of property values, we can specify the state in which a system currently is.
True
Once we have specified the state of the system from ____________, usually ____, all other properties properties ___________ or determined from the subset.
a small number of independent property values
2
have been defined
Equilibrium in thermodynamic systems are described as ______________.
being in a state of equilibrium
Properties are only defined when ______________, so no unbalanced potentials or __________ are within the system.
they are in a state of equilibrium
driving forces
For a system in equilibrium, there is no temperature or pressure difference.
True
A process is _____________.
the transformation of a system from 1 state to another
End states are the beginning and final state of a process.
True
We use a process diagram to know where we are within different properties or states.
True
A dot or circle with a number next to it in a process diagram represents the _________.
end state
In a process diagram, we include _______.
- the end states
- the direction of the process, indicated by an arrow
- the process path
The direction of a process is indicated by an arrow.
True
The process path is the line connecting two end points.
True
A complete description of a process requires:
- specification of the end states
- the process path
- the interactions across the boundaries
The process path tells us which way a process is going and which properties it goes through from 1 end point to another.
True
Examples of the interactions across the system boundaries are ______________.
heat, work, and mass (in an open system)
When a system undergoes a change of state, the change ______________ does not depend on the process connecting two end states.
in the value of the properties
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 ___________.
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.
When a system undergoes a change of state, the change in value of a property ____________.
does not depend on the process connecting the two end states
If we have a value that does depend on the process path between two end states, _____________.
that quantity is not a property
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, _______________.
heat, work, and mass
Cycles are _____________ (path has the same end state).
A process where the process path has identical end states
Systems that we study are not really in equilibrium, so we make an approximation in the modelling of the system.
True
A quasi-equilibrium process ___________
assumes that the system remains close to its equilibrium state during the process.
Quasi - equilibrium is an ___________ because very few real processes are in quasi-equilibrium.
idealization
Quasi-equilibrium process is the standard with which we compare real world processes.
True
Work-producing devices produce maximum work in the quasi-equilibrium state, and real world systems are a little under the quasi-equilibrium state.
True
