Chapter 1 Flashcards
it can be defined as the science of energy
thermodynamics
can be viewed as the ability to cause changes
energy
therme and dynamis meaning
heat and power
law that states that energy can change from one form to another; energy cannot be created or destroyed
conservation of energy principle
the change in the energy content of a body is equal to the difference between the energy __________ and energy _________
input and output
is simply an expression of the conversation of energy principle, and it asserts that energy is a thermodynamic property.
first law of thermodynamics
asserts that energy has quality as well as quantity, and actual processes occur in the direction of decreasing quality of energy.
2nd law of thermodynamics
a substance consists of a large number of particles called _____________
molecules
the macroscopic approach that does not require a knowledge of the behavior of individual particles is called _____________. It is also in direct and easy way.
classical thermodynamics
A more elaborate approach, based on the average behavior of large groups of individual particles is called ______________
statistical thermodynamics
Any physical quantity can be characterized by ____________
dimensions
the magnitude assigned to dimension is called ________
units
basic dimensions such as mass, length, and temperature are selected as _________
primary or fundamental dimensions
dimensions such as velocity and volume which are expressed in terms of the primary dimensions are called ____________________
secondary or derived dimensions
two sets of units that are used today
SI and English system
also known as USCS (United States Customary System)
English System
also known as the International System
SI
is a simple and logical system based on a decimal relationship between the various units, and it is being used for engineering work including England.
SI (International System)
has no apparent systematic numerical base
English system
1 lbm = kg
0.454 kg
formula of newton’s 2nd law
F=ma
1 slug = lbm
32.174 lbm
1 lbf = lbm ft/s^2
32.2
1N = 1?
kg m/s^2
The weight of a unit volume of a substance is called the ____________
specific weight
specific weight formula
density x gravity
a form of energy which can be defined as force times distance therefore it is Newton dot meter
Work
1 J = 1?
1 N dot meter
are identically equal to 1 and are unitless
unity conversion ratios
is defined as a quantity of matter or a region in space chosen for a study
system
the mass or region outside the system is called
surroundings
the real or imaginary surface that separates the system from its surroundings is called
boundary
consists of a fixed amount of mass, and no mass can cross its boundary. in this, energy can cross the boundary
closed system
other term of closed system
control mass
energy and mass cannot cross the boundary
isolated system
both mass and energy can cross the boundary
open system or control volume
the boundaries of a control volume is called a _______. they can be real or imaginary.
control surface
what forms the imaginary part of a control surface
entrance and exit areas
any characteristic of a system is called a
property
those that are independent of the mass of a system, such as temperature, pressure, and density.
Intensive properties
temperature
pressure
density
Intensive properties
those whose values depends on the size of the system
Extensive Properties
mass
volume
momentum
Extensive Properties
extensive properties per unit mass are called
specific properties
it s defined as mass per unit volume
density
density of water in SI
1000 kg/m^3 or 1 kg/L
density of water in English
62.4 lbm/ft^3
the reciprocal of density is the
specific volume
defined as volume per unit mass
specific volume
the ratio of the density of a substance to the density of some standard substance at a specified temperature.
specific gravity or relative density
the weight of a unit volume of a substance is called
specific weight
specific weight of water in SI
9.81 kN/m^3
specific weight of water in English
62.4 lbf/ft^3
thermodynamics deals with ______________states. which implies a state in balance
equilibrium
temperature is the same throughout the entire system
thermal equilibrium
there is no change in pressure at any point of the system with time
mechanical equilibrium
mass of each phase reaches an equilibrium level and stays there
phase equilibrium
chemical composition does not change with time and there is no chemical reaction
chemical equilibrium
temperature and specific volume are
independent
temperature and pressure are
dependent
any change that a system undergoes from one equilibrium state to another is called a
process
the series of states through which a system passes during a process is called the ________ of the process
path
when a process proceeds in such a manner that the system remains infinitesimally close to an equilibrium state at all times, it is called a
quasistatic or quasi-equilibrium process
can be viewed as sufficiently slow process that allows the system to adjust itself internally
quasi-equilibrium process
if piston was compressed suddenly, molecules will pile up in front of the piston creating a high-pressure region there. because of this pressure difference, the system can no longer be said to be in equilibrium, this makes the entire process ______________
non-quasi equilibrium
often used to designate a process for which a particular property remains constant.
iso-
is a process during which the temperature T remains constant
isothermal process
pressure P remains constant
isobaric process
specific volume V remains constant
isochoric or isometric process
a system is said to have undergone a ________ if it returns to its initial state at the end of the process
cycle
at the point when heat transfer stops, the two bodies are said to have reached ______________
thermal equilibrium
states that if two bodies are in thermal equilibrium with a third body, they are also in thermal equilibrium with each other.
zeroth law of thermodynamics
two bodies are in thermal equilibrium if both have the same temperature reading even if they are not in contact
zeroth law of thermodynamics
freezing point is also called as
ice point
boiling point is also called as
steam point
temperature scale that is independent of the properties of any substance or substances
thermodynamic temperature scale
the thermodynamic temperature scale in SI is
Kelvin
boiling point of water in K
373
boiling point of water in degrees C
100
boiling point of water in degrees F
212
freezing point of water in K
273
freezing point of water in degrees C
0
freezing point of water in degrees F
32
absolute zero of water in K
0
absolute zero of water in degrees C
-273
absolute zero of water in degrees F
-459
enable us to use a common basis for temperature measurements, and several have been introduced throughout history
temperature scales
centrigade scale
celsius scale
celsius scale is renamed after
A. Celsius
Fahrenheit is renanamed after
G. Fahrenheit
In celsius scale, ice and steam points were originally assigned the values _____ and _______
0 and 100
Fahrenheit ice and steampoint
32 and 212
temperature values are assigned at two different points
two-point scales
it is developed in conjunction with 2nd law of thermodynamics
thermodynamic temperature scales
thermodynamic temperature scale in SI
Kelvin
Kelvin is named after
Lord Kelvin
why is Rankine and Kelvin doesn’t have degrees?
since their lowest temperature is absolute zero and they cannot be negative
Celsius to Kelvin formula
K = deg C + 273.15
Fahrenheit to Rankine
R = deg F + 460
Kelvin to Rankiine
R = 1.8 K
Celsius to Fahrenheit
deg F = 1.8 deg C + 32
normal force exerted by fluid per unit area
Pressure
pressure only deals with ?(gas, liquid, or solid)
gas and liquid
counterpart of pressure in solids
normal stress
unit of pressure
N/m^2 or Pascal
1 Pa = ? N/m^2
1
different pressure units
bar
standard atmosphere
kilogram-force per square centimeter
1 bar = 1? Pa = ? MPa = ? kPa
10^5 Pa
0.1 MPa
100 KPa
1 atm = ? Pa
101, 325 Pa
1 kgf/ cm^2 = ? N/cm^2
9.807 N/cm^2
10^5 Pa = bar
1
0.1 MPa = bar
1
100 KPa = bar
1
101, 325 Pa = atm
1
1 atm = bar
1.01325 bar
1.01325 bar = atm
1
1 kgf/ cm^2 = N/m^2
9.807 x 10^4 N/m^2
1 kgf/ cm^2 = Pa
9.807 x 10^4 Pa
1 kgf/ cm^2 = bar
0.9807 bar
1 kgf/ cm^2 = atm
0.9679 atm
the actual pressure at a given position
absolute pressyre
it is measured relative to absolute vacuum
absolute pressure
difference between the absolute pressure and the local atmospheric pressure
gage pressure
pressure below atmospheric pressure are called
vacuum pressures
difference between the atmospheric pressure and the absolute pressure
vacuum pressure
it is the negative gage pressure
vacuum pressure
P gage =
P gage = P abs - Patm
P vac =
P vac = P atm - P abs
1 lb/ in^2 is also equivalent to 1?
psi
the ______________ value of the atmospheric pressure is used when getting the absolute pressure
local
pressure due to height formula
density x gravity x height (pgh)
P = Patm + Pgage
Pgage can be rewritten as?
pgh (density x gravity x height)
so, P = Patm + pgh
specific weight (y) formula
density x gravity (pg)
change in P = P2 - P1 = pg(change in h) = specific weight x change in height
△P = P2 - P1 = pg△h = y△h
△h is called?
pressure head
pressure in fluid increases _____________ with depth
linearly
for a given fluid, the vertical distance is sometimes used as a measure of pressure and it is called __________________
pressure head
commonly used to measure small and moderate pressure differences
manometer
A fluid column can be used to measure pressure differences and a device based on this principle is called
manometer
consists of glass or plastic U-tube containing one or more fluids such as mercury, water, alcohol, or oil.
manometer
pressure increases (downward or upward?)
downward
two points at the same elevation in a continuous fluid at rest are at the (same or different?) pressure
same
The last principle is a result of
Pascals’ Law
allows us to jump from one fluid column to the next in manometers without worrying about pressure change as long as we don’t jump over a different fluid and the fluid is at rest
The last principle which is a result of Pascal’s law
