Definitions

Question 1

Engine

Answer 1

A machine designed to convert one or more forms of energy into mechanical energy

Question 2

Heat engine

Answer 2

A physical or theoretical device that converts thermal energy to mechanical output

Question 3

Carnot heat engine

Answer 3

A hypothetical engine that operates on the reversible Carnot Cycle

Question 4

The system

Answer 4

The part whose properties we are studying

Question 5

Surroundings

Answer 5

Involve everything else outside or around the system

Question 6

Boundary

Answer 6

What the system exchanges matter or energy across to interact with its surroudings

Question 7

Isolated System

Answer 7

Neither matter nor energy can be exchanged

Question 8

Closed system

Answer 8

Only energy can be exchanged

Question 9

Open system

Answer 9

Both energy and matter can be exchanged

Question 10

Diathermal

Answer 10

When a system may be influenced thermally

Question 11

Conditions for thermodynamic equilibrium

Answer 11

-Mechanical equilibrium (constant pressure)
-Chemical equilibrium (constant particle concentration)
-Thermal equilibrium (constant temperature)

Question 12

Extensive vs intensive

Answer 12

A state variable that depends on the physical size of the system vs one that is independent of the system’s size

Question 13

Conditions for reversibility

Answer 13

-process can be reversed by an infinitesimal change in conditions
-quasistatic
-no hysteresis

Question 14

Quasisatic

Answer 14

Carried out so slowly that every state the system passes through may be considered an equilibrium state

Question 15

Hysteresis

Answer 15

When a process is reversed it does not retrace its previous path but follows a different one

Question 16

Irreversible

Answer 16

When energy is permanently lost from the system due to dissipative forces such as friction

Question 17

Common reversible processes

Answer 17

Isothermal, isochoric, isobaric, adiabatic

Question 18

Isothermal

Answer 18

The temperature of the system remains constant

Question 19

Isochoric

Answer 19

The volume of the system remains constant

Question 20

Isobaric

Answer 20

The pressure of the system remains constant

Question 21

Adiabatic (adiathermal)

Answer 21

No heat is exchanged between the system and its surroundings

Question 22

Thermal equilibrium

Answer 22

When there is no net heat flow between bodies after they have been in thermal contact with each other through a diathermal wall. They will have restricted value of their pressure/volume coordinate systems.

Question 23

The zeroth law

Answer 23

If two systems are separately in thermal equilibrium with a third, then they must also be in thermal equilibrium with each other

Question 24

Work is positive when

Answer 24

Work is done on the system of interest

Question 25

Work is negative when

Answer 25

The system does work on the surroundings

Question 26

Work

Answer 26

Energy transferred between a system and its surroundings when a force is applied over a distance or when the system undergoes a change in its external variables

Question 27

Heat

Answer 27

An energy transfer that happens between a system and its surroundings due to temperature difference

Question 28

First law

Answer 28

Energy is conserved and heat and work are both forms of energy. dU = dQ + dW

Question 29

A small change of entropy of a system, dS , is defined as

Answer 29

The small change in heat flow per unit temperature into the system, provided the heat flow corresponds to a reversible process

Question 30

Carnot cycle four steps

Answer 30

Isothermal expansion, adiabatic expansion, isothermal compression, adiabatic compression

Question 31

Kelvin statement

Answer 31

No process is possible whose sole result is the complete conversion of heat into work

Question 32

Clausius statement

Answer 32

No process is possible whose sole result is the transfer of heat from a colder to a hotter body

Question 33

Second law

Answer 33

No process is possible where the total entropy of the universe decreases. The total change in entropy is always greater than or equal to zero

Question 34

Carnots theorem

Answer 34

No engine operating between two given reservoirs can be more efficient than a carnot engine operating between the same two reservoirs

Question 35

Isentropic process

Answer 35

A process that is both adiabatic and reversible

Question 36

The second law- another version

Answer 36

The entropy of an isolated system tends to a maximum. As the universe of a whole is an isolated system, internal energy of universe is constant and entropy of universe can only increase, we are heading towards the heat death of the universe