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Thermodynamics is the branch of science which deals with energy interaction and it's effect on system and surrounding Energy is can be understood as the ability to cause changes System System can be a fixed mass or a region in space where our study in focused Surroundings is a Every thing except the system is called surrounding. The part of the surrounding which is directly affected by the system is called immediate surrounding Boundary is a real or imaginary surface which separates the system from the surrounding Boundary can be fixed or movable.
TYPES of system Pressure (gases) Acceleration to kinetic theory of gases the molecules of the gases are in continuous random motion and due to there random motion they collide with one or other and the walls of the container due to this collision force is extorted and avg normal force per unit area is termed pressure.
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Properties of the system:-Any characteristics of the system is called property of the system Properties can be classified as 1) Intensive, 2) Extensive .Intensive (intrinsic) Independent of mass of the system under consideration eg. Pressure, temperature, density etc. All specific properties are intensive property eg. Sp. Volume, sp. Enthalpy, sp. Internal energy etc. Extensive (Extrinsic):-Depends on mass of system under consideration eg. Volume, Internal energy, Enthalpy, entropy etc. State of the system and processes:-Any condition of the system is called as state of
specified by the properties of system If any one of the property changes, the
state of the system changes. The change in state of system is called
process. the infinite state through which the system pass, while going the
initial state to a final state is called process path. System State
The processes can be classified as : 1) Quasi-static 2) Non-Quasi-static A process is said to be a quasi-static process if it takes place infinitely slowly otherwise non quasi-static In quasi-static process the properties remain uniform throughout where as in non-quasi-static process the properties are non-uniform Friction-less quasi-static processes are reversible processes and also most efficient processes Reversible and Irreversible processes :- If process is said to be a reversible processes If it can be reversed in direction following the same path as that of the forward process without leaving any change in the system and surrounding Note :- Ideal flow through a nozzle , diffuser etc. Will be considered as reversible.
Macroscopic approach in this approach the avg. Molecular behavior is studied and individual behavior is disregarded. This approach is applied when the continue concept is solid Continuum is a matter is treated as continuously distributed without in void present continuum can be considered if the mean free path is much smaller than the system dimension. Mean free path it is the avg. Distance traveled by the molecules between two successive collisions. Microscopic approach this approach is applied when the matter become rare (Density is very less) hence the avg. Property become meaningful in this approach we focus on individual molecules. It is used in space exploration. One of the methods is ratified gas flow theory.
Thermodynamics Equilibrium is the system is said to be said to be thermodynamics equilibrium if it satisfied the following equilibrium conditions. Thermal equilibrium Equality of temperature , mechanical equilibrium Equality of forces, chemical equilibrium Chemical reaction potential should not be present , Phase equilibrium Mass of each phase remains constant with time .Pure substance :- A substance is said to be pure substance if it is of Homogeneous chemical composition throughout (P+ F = C + n ), P is a No. Of phase (solid, liquid, gas), C is a No. Of chemical component, N is a No. Of non-composition variable. DOF degree of freedom DOF is the minimum no. Of independent intensive variables required to fix the state of the system.
Zeroth law of thermodynamics According to Zeroth law if a body ‘A’ is in thermal equilibrium with body ‘C’ and also body ‘B’ is in thermal equilibrium with body ‘c’ then body ‘A’ and body ‘B’ is in thermal equilibrium with each other In Zeroth law body ‘c’ acts as thermometer Zeroth law gives the concept of temperature measurement Hotness or coolness is the feeling associated with the rate of Heat transfer Temperature is a parameter which represents random energy per unit molecules.
TYPES of thermometer Thermometers are based on finding thermometric property. Thermometric property is a property which helps in finding temperature for volume and length in mercury thermometer Temperature exactly show the physical condition of given fluid 1) Resistance Thermometer or Thermistor It is based on Wheatstone bridge principle and the Thermometric property is the resistance 2) Thermocouple It is based on see Beck effects acceleration to this effect of two metals are joint to form two different junction and they are maintain of different temperature then emf is generated which is directly properties to the temperature difference by measuring the emf the unknown temperature can be found Emf , voltage or current is the Thermometric property Peltier effects is opposite of see back effects and it is used for thermo- electric refrigeration 3) constant volume gas thermometer :- IV) constant pressure gas thermometer Both cv and cp gas thermometer are called ideal gas thermometer because material of construction is ideal gas Ideal gas thermometer are independent of material of construction that is if the gas is an ideal gas it does not matter which gas it is.
It is more important subject as a gate point of view and also important in SSC JE exam near about 30 number of question asked in SSC JE exam. In gate exam number numerical basis question asked and also in je exam objective type question asked. in this subject contain thermodynamic law more numerical asked on this basis. Thermodynamics are used in the heat conversion area areas Mechanical Engineering Thermo-Science design engine and power strips, heating, ventilation and air conditioning (HVAC) systems, heat exchange, gas sink, radiator, refrigeration, insulation and others are used. i will provide important notes for gate and ssc je very soon.