First law of thermodynamics Kishan Solanki(12me102) Patel manthan(12me132)

First Law of Thermodynamics The First Law is usually referred to as the Law of Conservation of Energy, i.e. energy can neither be created nor destroyed, but rather transformed from one state to another. The energy balance is maintained within the system being studied/defined boundary. The various energies associated are then being observed as they cross the boundaries of the system.

Energy Balance for Closed System Heat Work z Closed System Reference Plane,z = 0  V E in − E out =∆ E system 2

According to classical thermodynamics Qnet −Wnet =∆Esystem The total energy of the system, E system, is given as E = Internal energy + Kinetic energy + Potential energy E = U + KE + PE The change in stored energy for the system is ∆E=∆U+∆KE+∆PE The first law of thermodynamics for closed systems then can be written as Q net −W net =∆U+∆KE+∆PE If the system does not move with a velocity and has no change in elevation, the conservation of energy equation is reduced to Qnet −Wnet =∆U

Example of Closed Systems

What is Continuity equation A continuity equation in physics is a differential equation that describes the transport of a conserved quantity. Since mass, energy, momentum, electric charge and other natural quantities are conserved under their respective appropriate conditions; a variety of physical phenomena may be described using continuity equations.

General steady flow energy equation By conservation of energy, which can only be transferred and not created or destroyed leads to a continuity equation, an alternative mathematical statement of energy conservation to the thermodynamic laws. We can write the Continuity Equation in terms of Energy density and energy flux as: B By Fourier's law for a uniformly conducting medium,

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