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BITS Pil iBITS PilaniPilani Campus
BITS F111BITS F111Thermodynamics
BITS Pil iBITS PilaniPilani Campus
L t 1 Th l t ti dLecture 1: The language - systems, properties and equilibrium states. processes Th l ilib i d T tThermal equilibrium and Temperature
What is Thermodynamics?• Thermodynamics – Heat and Work, and Energy changes
i i l f iin material transformations
• Thermodynamics – where does a system go, and why?
Equilibrium
• Phenomenological or macroscopic thermodynamics – self-Phenomenological or macroscopic thermodynamics self
contained logical structure, independent of any assumptions
b t th d l i i i t t h iabout the underlying microscopic structure or mechanisms
• Statistical Thermodynamics – Bridges thermodynamics
with the microscopic world
BITSPilani, Pilani Campus
Nature of thermodynamics• Macroscopic bodies described by the values of a handful of
measurable attributes or properties
• Transformations undergone by bodies, interacting with other
bodies, described in terms of the corresponding changes in
values of propertiesp p
• Descriptions based on three laws derived from experience,
h l di t th id tifi ti f t th leach leading to the identification of a new property – thermal
equilibrium and temperature, impossibility of perpetual motion
and energy, direction of a natural process, and entropy.
BITSPilani, Pilani Campus
What is studied?
System, Properties, Equilibrium States, State Functions Process Cycle
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Functions, Process, Cycle
Systems – Control VolumeControl Surface
System ‐ device or a combination of many ydevices that contain aquantity of matter under considerationconsideration.
BITSPilani, Pilani Campus
Systems and Surroundings• Part of the universe set apart for detailed study
• Closed System or Control Mass – One that cannot
exchange matter, but can exchange energy with the
surroundings, ie., special case of a control volume in which
matter does not cross control surface
• Open System – One that can exchange both matter and
ith th dienergy with the surroundings
• Isolated System – One that does not interact in any way
with the surroundings
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Properties and Equilibrium State• Property – measurable, macroscopic attribute of a system
( ) ( )– eg., Volume (geometric), Pressure (mechanical), and
Temperature (thermodynamic)
• Equilibrium State – “all properties unchanging with time”,
with values that do not depend on the historyp y
• Mechanical, Chemical, Thermal - Thermodynamic
• State prescribed by values of properties, and vice-versa
• Question – how many properties to specify equilibrium
state?BITSPilani, Pilani Campus
Properties• Extensive – one whose value increases in direct proportion
( ) fto the mass (extent) of the system, eg., Volume, Energy,
Mass
• Intensive – one whose value is independent of the extent
(mass) of the system, eg., Pressure, Viscosity, Density( ) y , g , , y, y
• Specific – Extensive property per unit mass, eg., Specific
V l V l /MVolume v = Volume/Mass
• Continuum approximation
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