It is the branch of physics, which deals with the transformation of heat energy into mechanical energy.
That branch of physics which deals with the various phenomena of energy-related properties of matter, especially with the law of transformation of heat with the other forms of energy and vice versa, is it called thermodynamics.
Thermodynamics explains the bulk properties of matter such as pressure, specific heat etc. In a microscopic way that is it makes no difference is to detail Atomic or molecular or other microscopic constituents of Matter.
Any substance in which we can store energy and from which we can remove energy is it called working substance. in thermodynamics, it is also called working fluid.
Any liquid or gas which flows by applying shear stress is called fluid.
A system is that portion of the universe, an atom, a certain quantity of matters, a Galaxy or a certain volume in space that we want to study is called system.
Anything under scientific concentration is called a system.
A system is enclosed by boundaries. A boundary may be real or imaginary, they may be fixed or moving.
The region around the system or the Matter around the system that can be interacting with the system is called surroundings.
Types of the system:
There are three types of system which are
A system which can exchange both energy and Mass to the surrounding is called an open system. For example, the tree is an open system.
A system which can exchange energy but not mass with the surrounding is called a closed system. For example, gas in a cylinder having contacting base, insulating walls and position. We can give heat energy to it but cannot transmit Mass through its boundary.
A system which can neither exchange heat energy nor mass to the surrounding is it called an isolated system.
A system for which we study thermodynamics properties is called the thermodynamic system.
State and State variable:
The description of the state of the system is done in terms of thermodynamics are microscopic measuring Attributes of the system, which are called State variables such as pressure, volume, temperature, etc. A thermodynamic system now also be defined as one which can be specified in terms of State variables.
the condition of the system at any time instant is called state.
Any quantity depends upon the state of the system and independent of the path is called thermodynamic property. For example volume, mass etc.