Option B2

Question 1

State

The first law of thermodynamics

Answer 1

Question 2

Define Internal energy

Answer 2

Internal energy is defined as the energy associated with the random, disordered motion of molecules.

should be equal to

Total Potential energy + Random kinetic energy of moleucles

Question 3

State

The second law of thermodynamics

in Clausius form

Answer 3

It is impossible for thermal energy to flow from a cold to a hot object without performing any work.

Question 4

State

The second law of thermodynamics

in Kelvin form

Answer 4

It is impossible, in a cyclic process, to completely convert heat into mechanical work.

Question 5

State

The second law of thermodynamics as a

consequence of Entropy

Answer 5

The total entropy of a system either increase or remain constant, it never decreases.

Question 6

Formula

of calculating

Change in Internal Energy

Answer 6

Question 7

Answer 7

Question 8

Explain

the sign convention of

quantum energy/heat transfer

between a system and its surrounding (Q)

Answer 8

Q > 0 if heat is supplied to the system

Q < 0 if heat is released by the system

Question 9

What is the formula of

calculating Workdone (W)

in first law of thermodynamic

Answer 9

Question 10

Explain the sign convention

of Workdone (W) in

the first law of thermodynamic

Answer 10

Question 11

Describing the first law of thermodynamics as a statement of conservation of energy

Answer 11

Question 12

What is

Entropy?

Answer 12

Entropy is

A measure of disorder

Question 13

Describle

how a system will become

more disorder (i.e. entropy increase)?

Answer 13

A system will be more disorder if it is more difficult to determine the position of molecules, e.g.

1. Temperature increase
2. Volume increase
3. No of molecules increase
4. Change of stage from Solid to Liquid to Gas

Question 14

What is the formula

of calculating

Change in Entropy?

Answer 14

Question 15

What is the entropy change for

Reversible and Inreversible Process

according to the second law of thermodynamic?

Answer 15

·

Question 16

Under what condition that

A process will have decrease in entropy?

Answer 16

A process with have decrease in entropy

only if energy is supplied

Question 17

In what way do the entropy

of a universe (or a closed system)

change?

Answer 17

The entropy of a universe (or a closed system) is constantly increasing, never decreasing

Question 18

When will two systems

are said to be in same state?

Answer 18

Two systems are said to be in same state if they have the same pressure, same volume and same temperature and hence they have the same internal energy.

Question 19

What is

the Ideal Gas Law?

Answer 19

Question 20

What is the work done

of the cyclic process AB

In a PV graph?

Answer 20

work done = area within the loop

Question 21

What does the direction of

a cyclic process indicate?

Answer 21

Question 22

Characteristics of a

Isochoric or isovolumetric process

Answer 22

Question 23

Characteristics of a

Isobaric process

Answer 23

Question 24

Characteristics of

an Isothermal process

Answer 24

Question 25

Characteristics of

an Adiabatic Process

Answer 25

Question 26

How to

distinguish between

adiabatic and isothermal curve?

Answer 26

Question 27

What is the

difference between

Adiabatic Compression

and

Isothermal Compression?

Answer 27

Question 28

What is a

Carnot cycle ?

Answer 28

The Carnot cycle represents the cycle of processes for a theoretical heat engine with the maximum possible efficiency. Such an idealized engine is called a Carnot engine.

Question 29

What are the processes

in a Carnot Cycle ?

Answer 29

Question 30

What is

the Thermal efficiency

for a Carnot engine?

Answer 30

Question 31

What is

the Thermal efficiency

for a heat engine?

Answer 31

Question 32

Explain, in terms of the energy of its molecules, why the temperature of a pure substance does not change during melting.

Answer 32

Energy supplied during melting is used to break bond between water molecules, the energy supplied increase potential energy of molecules, and no increase in kinetic energy, so there is no change in temperature.

Question 33

State what is meant by an isothermal process

Answer 33

An isothermal process is a process in which temperature remains constant

Question 34

State what is meant by a

Isochoric or isovolumetric process?

Answer 34

Process in which the volume of the system does not change

Question 35

State what is meant by

an Isobaric process?

Answer 35

Process in which the pressure of the system is constant.

Question 36

State what is meant by

an Adiabatic Process?

Answer 36

Process in which there is no exchange of thermal energy between a system and it surroundings.

Question 37

Explain why it is not possible for an engine, operating in a cycle, to be 100% efficient

Answer 37

For an engine to be operating in a cycle, the system must return to original conditions (P, V, and T), to do that, some of the thermal energy absorbed by gas must be given off to the surroundings; hence not all thermal energy absorbed by gas can be converted to work; it is the second law of thermodynamics;

Question 38

Describe how the ideal gas constant R is defined.

Answer 38

Question 39

With respect to a gas, explain the meaning of the terms thermal energy and internal energy

Answer 39

Thermal energy (Q) is the energy transferred between two objects when are at different temperatures.

Internal energy (U) is the energy associated with the random, disordered motion of molecules, which comprises of the total potential energy and random kinetic energy of the molecules of the gas.

Question 40

Outline why an efficiency calculation is important for an engineer designing a heat engine.

Answer 40

So as to reduce energy loss; increase engine performance; effective use of fuel; etc.

Question 41

There are various equivalent versions of the second law of thermodynamics. Outline the benefit gained by having alternative forms of a law.

Answer 41

There are different modellings, allow testing in different ways and the laws can be applied in different situations.

Question 42

Define Thermal Energy

Answer 42

Energy transferred between two objects which are at different temperature