Definitions

Question 1

First Law of thermodynamics

Answer 1

Conservation of energy

Question 2

Second Law of thermodynamics

Answer 2

quality and quantity of energy
direction of decreasing quality of energy

Question 3

What is a closed system

Answer 3

• System that always contains the same matter
• No transfer of mass across boundary
• Energy can cross the boundary in forms of heat and work

Question 4

Isolated system

Answer 4

A type of closed system
No transfer at all, mass or energy

Question 5

Control Volume

Answer 5

A type of open system
-A given region of space through which mass flows
-Mass and energy can cross boundary

Question 6

What is an intensive property, list them

Answer 6

properties that are independent of size
pressure, temperature, density, specific volume

Question 7

What is an extensive property, list them

Answer 7

Properties that are dependent on the size of the system
mass, volume, energy

Question 8

What is a state

Answer 8

a list of properties

Question 9

What is a process

Answer 9

a transformation from 1 state to another

Question 10

What is an equilibrium

Answer 10

• isolated system, no interactions
• state can still change as intensive properties tend toward uniform values
• when changes cease, it as reached equilibrium state

Question 11

Density

Answer 11

an intensive property
row = mass divide by volume

Question 12

Specific volume

Answer 12

reciprocal of density
intensive property

Question 13

Pressure

Answer 13

power over area

Question 14

different types of pressure (2 types)

Answer 14

absolute pressure
- pressure relative to a vacuum
Gage pressure
- pressure relative to atmosphere

Question 15

Compare vacuum pressure, atmospheric pressure, absolute pressure, and gage pressure

Answer 15

P(vac) = P(atm) - P(abs)
P(gage) = P(abs) - P(atm)

Question 16

describe pressure

Answer 16

also called normal stress
- perpendicular to surface
- P = (sigma)(n) = W/A
- pressure in a fluid only changes in the vertical direction
P(atm)= (row)gh

Question 17

Buoyant force

Answer 17

has magnitude = weight of displaced liquid

Question 18

Pascal’s law

Answer 18

Force applied by a fluid is proportional to the surface area
F1/A1 = F2/A2

Question 19

What is the sign of work

Answer 19

W > 0 if work is done by the system on the surroundings
W < 0 if work is done on the system by the surroundings

Question 20

Quasi-equilibrium

Answer 20

• An idealized process
• close enough to equilibrium
• only minor changes in P, T
• ” gives time for the whole system to catch up”

Question 21

What is a polytropic process

Answer 21

one in which PV^n is constant

Question 22

What is Q, and its sign

Answer 22

amount of heat transfer
- Q > 0, transferred into the system
- Q < 0 transferred out of the system

Question 23

What is an isothermal process

Answer 23

A process in which temperature remains constant, other properties can change
dT = 0

Question 24

What is an Adiabatic Process

Answer 24

A process in which the system does not exchange Q with the surroundings
dQ = 0

Question 25

3 modes of heat transfer

Answer 25

Conduction, Convection, and Radiation

Question 26

What is conduction

Answer 26

heat transfer through direct contact, either two solids or solid and stationary fluid

Question 27

What is convection

Answer 27

Energy transfer between solid surface and gas or liquid
rate of convection is governed by newtons law of cooling
Qc = hA[Tb - Tf]

Question 28

What is radiation

Answer 28

Heat transfer without medium
E & M waves
governed by Stefan Boltzman Law

Question 29

Fourier’s Law does what

Answer 29

governs conduction
Q(dot) = -kA(dT/dx)
if temp varies linearly
dT/dx = T2-T1/L