Chapter 2.

Energy Interaction Model

Energy Interaction Model
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Algebraic Representations

Closed system:    ΔEtotal = ΣΔEi = ΔE1 + ΔE2 + ΔE3 + … = 0
Open system:      ΔEtotal = ΣΔEi = ΔE1 + ΔE2 + ΔE3 + … = Q + W

Diagrammatic Representation

Generic Example involving two physical systems, three energy systems, and with Heat Input

Identification of beginning and end of interval:

beginning
end

Physical system:

Physical thing 1
Physical thing 2

Commonly Used Energy Systems in Part 1

Useful Groupings of Energy Systems

Mechanical Energy
Sum of kinetic and potential energies associated with the physical “objects.”


Internal Energy, U
Sum of kinetic and potential energies associated with the individual molecules/atoms comprising a substance, as well as the energies associated with their atomic and nuclear energies. We will mostly deal only with changes in the energies associated with thermal and bond energies (chemical energies).