About Lesson
Introduction
- Thermodynamics is that branch of physics which deals with concepts of heat and temperature and their relation to energy and work.
- We can also consider it as a macroscopic science which deals with bulk systems and tells us about system as a whole.
- In this chapter we will learn about the laws of thermodynamics which describes the system in terms of macroscopic variables, reversible and irreversible processes. Finally we will also learn on what principle heat engines, refrigerators and Carnot engine work.
Examples: – Refrigerator, steam engine

Thermodynamics vs. Mechanics
- In Thermodynamics we consider only the state of the object which means we will only consider macroscopic variables like pressure, volume and temperature.
- In mechanics we consider the motion, velocity and acceleration of the object.
For eg: –
- In mechanics if a bullet is fired from a gun we will consider the motion of bullet and its velocity, acceleration etc.

Thermal Equilibrium
- Two systems are said to be in thermal equilibrium if the temperatures of the two systems are equal.
- In mechanics if the net force on a system is zero, the system is in equilibrium.
- In Thermodynamics equilibrium means all the macroscopic variables (pressure, temperature and volume) don’t change with time. They are constant throughout.
For Example: –
- Consider two bodies at different temperatures one is at 300C and another at 600C then the heat will flow from body at higher temperature to the body at lower temperature.
- Heat will flow till both bodies acquire same temperature.
- This state when there is no heat flow between two bodies when they acquire the same temperature is known as thermal equilibrium.

Types of Equilibrium
Thermal Equilibrium: – Two systems are said to be in thermal equilibrium with each other if the temperatures of both the systems do not change with time.
Chemical Equilibrium: – Two systems are said to be in chemical equilibrium with each other if the composition of the system does not change over time.
Mechanical Equilibrium: – Two systems are said to be in mechanical equilibrium with each other if the pressure of the system doesn’t change with time.
A system is said to be in Thermodynamic equilibrium when all of its macroscopic variables are constant.
Exercise Files
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Lesson List
Class 11 Physics Chapter 1 Physical World
Section Name Topic Name
1 Physical World
1.1 What is physics?
1.2 Scope and excitement of physics
1.3 Physics, technology and society
1.4 Fundamental forces in nature
1.5 Nature of physical laws
0/7
Class 11 Physics Chapter 2 Unit and Measurements
Unit and Measurements
0/11
Class 11 Physics Chapter 3 Motion In A Straight Line
Section Name Topic Name
3 Motion in a Straight Line
3.1 Introduction
3.2 Position, path length and displacement
3.3 Average velocity and average speed
3.4 Instantaneous velocity and speed
3.5 Acceleration
3.6 Kinematic equations for uniformly accelerated motion
3.7 Relative velocity
0/7
Class 11 Physics Chapter 4 Motion In A Plane
4 Motion in a plane
4.1 Introduction
4.2 Scalars and vectors
4.3 Multiplication of vectors by real numbers
4.4 Addition and subtraction of vectors – graphical method
4.5 Resolution of vectors
4.6 Vector addition – analytical method
4.7 Motion in a plane
4.8 Motion in a plane with constant acceleration
4.9 Relative velocity in two dimensions
4.10 Projectile motion
4.11 Uniform circular motion
0/8
Class 11 Physics Chapter 5 Laws of motion
Section Name Topic Name
5 Laws of motion
5.1 Introduction
5.2 Aristotle’s fallacy
5.3 The law of inertia
5.4 Newton’s first law of motion
5.5 Newton’s second law of motion
5.6 Newton’s third law of motion
5.7 Conservation of momentum
5.8 Equilibrium of a particle
5.9 Common forces in mechanics
5.10 Circular motion
5.11 Solving problems in mechanics
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Class 11 Physics Chapter 6 Work Energy and Power
Section Name Topic Name
6 Work Energy and power
6.1 Introduction
6.2 Notions of work and kinetic energy : The work-energy theorem
6.3 Work
6.4 Kinetic energy
6.5 Work done by a variable force
6.6 The work-energy theorem for a variable force
6.7 The concept of potential energy
6.8 The conservation of mechanical energy
6.9 The potential energy of a spring
6.10 Various forms of energy : the law of conservation of energy
6.11 Power
6.12 Collisions
0/8
Class 11 Physics Chapter 7 Rotation motion
Topics
Introduction
Centre of mass
Motion of COM
Linear Momentum of System of Particles
Vector Product
Angular velocity
Torque & Angular Momentum
Conservation of Angular Momentum
Equilibrium of Rigid Body
Centre of Gravity
Moment of Inertia
Theorem of perpendicular axis
Theorem of parallel axis
Moment of Inertia of Objects
Kinematics of Rotational Motion about a Fixed Axis
Dynamics of Rotational Motion about a Fixed Axis
Angular Momentum In Case of Rotation about a Fixed Axis
Rolling motion
0/6
Class 11 Physics Chapter 8 Gravitation
Section Name Topic Name
8 Gravitation
8.1 Introduction
8.2 Kepler’s laws
8.3 Universal law of gravitation
8.4 The gravitational constant
8.5 Acceleration due to gravity of the earth
8.6 Acceleration due to gravity below and above the surface of earth
8.7 Gravitational potential energy
8.8 Escape speed
8.9 Earth satellite
8.10 Energy of an orbiting satellite
8.11 Geostationary and polar satellites
8.12 Weightlessness
0/8
Class 11 Physics Chapter 9 mechanics properties of solid
Section Name Topic Name
9 Mechanical Properties Of Solids
9.1 Introduction
9.2 Elastic behaviour of solids
9.3 Stress and strain
9.4 Hooke’s law
9.5 Stress-strain curve
9.6 Elastic moduli
9.7 Applications of elastic behaviour of materials
0/6
Class 11 Physics Chapter 10 Mechanical Properties of Fluids
Section Name Topic Name
10 Mechanical Properties Of Fluids
10.1 Introduction
10.2 Pressure
10.3 Streamline flow
10.4 Bernoulli’s principle
10.5 Viscosity
10.6 Reynolds number
10.7 Surface tension
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Class 11 Physics Chapter 11 Thermal Properties of matter
Section Name Topic Name
11 Thermal Properties of matter
11.1 Introduction
11.2 Temperature and heat
11.3 Measurement of temperature
11.4 Ideal-gas equation and absolute temperature
11.5 Thermal expansion
11.6 Specific heat capacity
11.7 Calorimetry
11.8 Change of state
11.9 Heat transfer
11.10 Newton’s law of cooling
0/5
Class 11 Physics Chapter 12 Thermodynamics
Section Name Topic Name
12 Thermodynamics
12.1 Introduction
12.2 Thermal equilibrium
12.3 Zeroth law of thermodynamics
12.4 Heat, internal energy and work
12.5 First law of thermodynamics
12.6 Specific heat capacity
12.7 Thermodynamic state variables and equation of state
12.8 Thermodynamic processes
12.9 Heat engines
12.10 Refrigerators and heat pumps
12.11 Second law of thermodynamics
12.12 Reversible and irreversible processes
12.13 Carnot engine
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Class 11 Physics Chapter 13 Kinetic Theory
Section Name Topic Name
13 Kinetic Theory
13.1 Introduction
13.2 Molecular nature of matter
13.3 Behaviour of gases
13.4 Kinetic theory of an ideal gas
13.5 Law of equipartition of energy
13.6 Specific heat capacity
13.7 Mean free path
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Class 11 Physics Chapter 14 Oscillations
Section Name Topic Name
14 Oscillations
14.1 Introduction
14.2 Periodic and oscilatory motions
14.3 Simple harmonic motion
14.4 Simple harmonic motion and uniform circular motion
14.5 Velocity and acceleration in simple harmonic motion
14.6 Force law for simple harmonic motion
14.7 Energy in simple harmonic motion
14.8 Some systems executing Simple Harmonic Motion
14.9 Damped simple harmonic motion
14.10 Forced oscillations and resonance
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Class 11 Physics Chapter 15 Waves
Section Name Topic Name
15 Waves
15.1 Introduction
15.2 Transverse and longitudinal waves
15.3 Displacement relation in a progressive wave
15.4 The speed of a travelling wave
15.5 The principle of superposition of waves
15.6 Reflection of waves
15.7 Beats
15.8 Doppler effect
0/8
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