The document discusses the four laws of thermodynamics: (1) the zeroth law which underlies the definition of temperature, (2) the first law which mandates conservation of energy and states that heat is a form of energy, (3) the second law which states that entropy of the universe always increases, and (4) the third law which concerns entropy at absolute zero temperature. It also defines key thermodynamic concepts like internal energy, heat, and work.

1. LAWS OF THERMODYNAMICS INTRODUCTION

2. The laws of thermodynamics, in principle, describe the specifics for the transport of heat and work in thermodynamic processes. Since their inception, however, these laws have become some of the most important in all of physics and other branches of science connected to thermodynamics. LAWS OF THERMODYNAMICS

5. FAMILIARIZATION Internal Energy: It is defined as the energy associated with the random, disordered motion of molecules. It is separated in scale from the macroscopic ordered energy associated with moving objects; it refers to the invisible microscopic energy on the atomic and molecular scale. For example, a room temperature glass of water sitting on a table has no apparent energy, either potential or kinetic . But on the microscopic scale it is a seething mass of high speed molecules. If the water were tossed across the room, this microscopic energy would not necessarily be changed when we superimpose an ordered large scale motion on the water as a whole. LAWS OF THERMODYNAMICS

6. FAMILIARIZATION Heat: It may be defined as energy in transit from a high temperature object to a lower temperature object. An object does not possess "heat"; the appropriate term for the microscopic energy in an object is internal energy. The internal energy may be increased by transferring energy to the object from a higher temperature (hotter) object - this is called heating. LAWS OF THERMODYNAMICS

7. FAMILIARIZATION Work: When work is done by a thermodynamic system, it is usually a gas that is doing the work. The work done by a gas at constant pressure is W = p dV, where W is work, p is pressure and dV is change in volume. For non-constant pressure, the work can be visualized as the area under the pressure-volume curve which represents the process taking place. LAWS OF THERMODYNAMICS

8. The Zeroth Law This law expresses that having in existence three systems, A, B, and C, if A is in equilibrium with C and B is in equilibrium with C, then A and B will also be in equilibrium. All three systems will be in equilibrium in temperature. If any of these systems are in contact with other systems, there will be compensation in the temperature level of all the systems involved. That is, they will all have the same temperature. Mathematically, we know that, if A= B & A=C then A=B=C Thermodynamically, as per the Zeroth Law, if T A = T B & T A =T C then T A = T B =T C LAWS OF THERMODYNAMICS

9. FAMILIARIZATION Work: When work is done by a thermodynamic system, it is usually a gas that is doing the work. The work done by a gas at constant pressure is W = p dV, where W is work, p is pressure and dV is change in volume. For non-constant pressure, the work can be visualized as the area under the pressure-volume curve which represents the process taking place. LAWS OF THERMODYNAMICS