Thermodynamics: Lecture 1

Sai Jagan Mohan, Department of Mechanical Engineering

13th January, 2015

BITSx F111: Thermodynamics Birla Institute of Technology & Science

The Role of Thermodynamics

Introduce public education with

moderation, avoiding bloodshed if

possible- Saltykov-Shchedrin

What do we want to do? Ans:Understand the properties of materials

Attempt via a Microscopic picture

We need to keep track of an enormous number ofmolecules (∼Avagadro’s number)

The situation gets quite complicated :( :(: for mostproblems of importance.

BITSx F111: Thermodynamics Birla Institute of Technology & Science

The Role of Thermodynamics

Introduce public education with

moderation, avoiding bloodshed if

possible- Saltykov-Shchedrin

What do we want to do? Ans:Understand the properties of materials

Attempt via a Microscopic picture

We need to keep track of an enormous number ofmolecules (∼Avagadro’s number)

The situation gets quite complicated :( :(: for mostproblems of importance.

BITSx F111: Thermodynamics Birla Institute of Technology & Science

The Role of Thermodynamics

Introduce public education with

moderation, avoiding bloodshed if

possible- Saltykov-Shchedrin

What do we want to do? Ans:Understand the properties of materials

Attempt via a Microscopic picture

We need to keep track of an enormous number ofmolecules (∼Avagadro’s number)

The situation gets quite complicated :( :(: for mostproblems of importance.

BITSx F111: Thermodynamics Birla Institute of Technology & Science

The Role of Thermodynamics

Introduce public education with

moderation, avoiding bloodshed if

possible- Saltykov-Shchedrin

What do we want to do? Ans:Understand the properties of materials

Attempt via a Microscopic picture

We need to keep track of an enormous number ofmolecules (∼Avagadro’s number)

The situation gets quite complicated :( :(: for mostproblems of importance.

BITSx F111: Thermodynamics Birla Institute of Technology & Science

The Role of Thermodynamics

Introduce public education with

moderation, avoiding bloodshed if

possible- Saltykov-Shchedrin

What do we want to do? Ans:Understand the properties of materials

Attempt via a Microscopic picture

We need to keep track of an enormous number ofmolecules (∼Avagadro’s number)

The situation gets quite complicated :( :(: for mostproblems of importance.

BITSx F111: Thermodynamics Birla Institute of Technology & Science

The Role of Thermodynamics

Introduce public education with

moderation, avoiding bloodshed if

possible- Saltykov-Shchedrin

What do we want to do? Ans:Understand the properties of materials

Attempt via a Microscopic picture

We need to keep track of an enormous number ofmolecules (∼Avagadro’s number)

The situation gets quite complicated :( :(: for mostproblems of importance.

BITSx F111: Thermodynamics Birla Institute of Technology & Science

The Role of Thermodynamics

Introduce public education with

moderation, avoiding bloodshed if

possible- Saltykov-Shchedrin

What do we want to do? Ans:Understand the properties of materials

Attempt via a Microscopic picture

We need to keep track of an enormous number ofmolecules (∼Avagadro’s number)

The situation gets quite complicated :( :(: for mostproblems of importance.

BITSx F111: Thermodynamics Birla Institute of Technology & Science

The Role of Thermodynamics

Introduce public education with

moderation, avoiding bloodshed if

possible- Saltykov-Shchedrin

What do we want to do? Ans:Understand the properties of materials

Attempt via a Microscopic picture

We need to keep track of an enormous number ofmolecules (∼Avagadro’s number)

The situation gets quite complicated :( :(: for mostproblems of importance.

BITSx F111: Thermodynamics Birla Institute of Technology & Science

The Role of Thermodynamics

Grand Question: What do I do now? Do

I have options?

BITSx F111: Thermodynamics Birla Institute of Technology & Science

The Role of Thermodynamics

Grand Question: What do I do now? Do

I have options?

BITSx F111: Thermodynamics Birla Institute of Technology & Science

Simulation of a Complicated Situation

Please tell me your strategy, that will

help your friend gain some precious time.

BITSx F111: Thermodynamics Birla Institute of Technology & Science

Simulation of a Complicated Situation

Please tell me your strategy, that will

help your friend gain some precious time.

BITSx F111: Thermodynamics Birla Institute of Technology & Science

Summary of Strategy

Venture boldly with an intelligent guess.

Discover laws.

Laws can never be proved to be right,

they can only be proved to be wrong.

This bold leap combined with clever

reasoning can spring a few pleasant

surprises.

BITSx F111: Thermodynamics Birla Institute of Technology & Science

Summary of Strategy

Venture boldly with an intelligent guess.

Discover laws.

Laws can never be proved to be right,

they can only be proved to be wrong.

This bold leap combined with clever

reasoning can spring a few pleasant

surprises.

BITSx F111: Thermodynamics Birla Institute of Technology & Science

Summary of Strategy

Venture boldly with an intelligent guess.

Discover laws.

Laws can never be proved to be right,

they can only be proved to be wrong.

This bold leap combined with clever

reasoning can spring a few pleasant

surprises.

BITSx F111: Thermodynamics Birla Institute of Technology & Science

Summary of Strategy

Venture boldly with an intelligent guess.

Discover laws.

Laws can never be proved to be right,

they can only be proved to be wrong.

This bold leap combined with clever

reasoning can spring a few pleasant

surprises.

BITSx F111: Thermodynamics Birla Institute of Technology & Science

Example: Dimensional Analysis

Law: The formulae of physics are

independent of dimension.

Clever reasoning is required to realize

the restriction imposed by this Law of

Physics. This (restriction) is often useful

in a complex situation.

BITSx F111: Thermodynamics Birla Institute of Technology & Science

Example: Dimensional Analysis

Law: The formulae of physics are

independent of dimension.

Clever reasoning is required to realize

the restriction imposed by this Law of

Physics. This (restriction) is often useful

in a complex situation.

BITSx F111: Thermodynamics Birla Institute of Technology & Science

Example: Dimensional Analysis

Law: The formulae of physics are

independent of dimension.

Clever reasoning is required to realize

the restriction imposed by this Law of

Physics. This (restriction) is often useful

in a complex situation.

BITSx F111: Thermodynamics Birla Institute of Technology & Science

Guess + Reasoning=?

Thermodynamics: The remarkableguesses of Mr Sadi Carnot and his finereasoning.

The restrictions posed by the two laws ofthermodynamics leads to astonishing relations betweenthe properties of matter.

BITSx F111: Thermodynamics Birla Institute of Technology & Science

Guess + Reasoning=?

Thermodynamics: The remarkableguesses of Mr Sadi Carnot and his finereasoning.

The restrictions posed by the two laws ofthermodynamics leads to astonishing relations betweenthe properties of matter.

BITSx F111: Thermodynamics Birla Institute of Technology & Science

The Role of Macroscopic Thermodynamics

The determination of the relationships

among the various properties of materials

without knowing their internal structure

is the subject of Thermodynamics

- Prof R P Feynman.

BITSx F111: Thermodynamics Birla Institute of Technology & Science

The Role of Macroscopic Thermodynamics

The determination of the relationships

among the various properties of materials

without knowing their internal structure

is the subject of Thermodynamics

- Prof R P Feynman.

BITSx F111: Thermodynamics Birla Institute of Technology & Science

The Role of Macroscopic Thermodynamics

Thermodynamics is the study of the

restrictions on the possible properties of

matter that follow from the symmetry

properties of the fundamental laws of

Physics

Herbert Callen

BITSx F111: Thermodynamics Birla Institute of Technology & Science

The Role of Macroscopic Thermodynamics

Thermodynamics is the study of the

restrictions on the possible properties of

matter that follow from the symmetry

properties of the fundamental laws of

Physics

Herbert Callen

BITSx F111: Thermodynamics Birla Institute of Technology & Science

The Role of Macroscopic Thermodynamics:

Examples

For ideal gases Cp(T ) − Cv(T ) = R .

U(T ) for an ideal gas.

During Phase transformations (Clausius

Clapeyron equation)

L

T (VG − VL)=

(∂Pvap

∂T

)

BITSx F111: Thermodynamics Birla Institute of Technology & Science

The Role of Macroscopic Thermodynamics:

Examples

For ideal gases Cp(T ) − Cv(T ) = R .

U(T ) for an ideal gas.

During Phase transformations (Clausius

Clapeyron equation)

L

T (VG − VL)=

(∂Pvap

∂T

)

BITSx F111: Thermodynamics Birla Institute of Technology & Science

The Role of Macroscopic Thermodynamics:

Examples

Relation for Joule Thompson Expansion

µ =

(∂T

∂P

)h

=1

cp

[T

(∂v

∂T

)P

− v

]

BITSx F111: Thermodynamics Birla Institute of Technology & Science

The Role of Macroscopic Thermodynamics:

Examples

Relation for Joule Thompson Expansion

µ =

(∂T

∂P

)h

=1

cp

[T

(∂v

∂T

)P

− v

]

BITSx F111: Thermodynamics Birla Institute of Technology & Science