3
The First Law: The Production of Heat
and the Principle of Conservation
of Energy
Abstract
Pedagogically speaking, the formulation of the first law of thermodynamics is
the real beginning of the study of heat and energy. Rejecting caloric’s
materiality, the mechanical equivalent of heat proved that heat can be measured
in terms of mechanical energy and the heat—mechanical energy equivalence led
to the first law (the energy conservation principle) and that heat is a form of
energy, the lowest-grade form of energy. The conservation principle infers that
energy can be neither created nor destroyed, thus, only its form can be
transformed. This conceptual understanding and the application of dU ¼
dQ À pdV for thermodynamic processes are two key takeaways of this chapter.
The nature of the transformation of energy forms is the outstanding question
remaining for further investigation.
Keywords
Adiabatic work Á Internal energy Á Mechanical equivalent of heat (MEH) Á The
MEH constant (J) Á Conceptual differentiation of caloric Á The first law of
thermodynamics Á Heat versus heat Á Enthalpy Á Heat capacities Á Caloric
equation of state for ideal gases Á Polytropic processes of ideal gases
3.1 Introduction
With the successful determination of c p À c V and the success of the theory of
adiabatic heating, the caloric theory was showing itself to be a powerful instrument
indeed! Just at this point, the scientific tide began to turn against the Laplacian
orthodoxy. The dynamical theory of heat, an older but at that point a less developed
theory of heat, was making a comeback to challenge the caloric theory as part of the
anti-Laplacian movement.
© Springer Nature Switzerland AG 2020
L.-S. Wang, A Treatise of Heat and Energy, Mechanical Engineering Series,
https://doi.org/10.1007/978-3-030-05746-6_3
37
The First Law: The Production of Heat
and the Principle of Conservation
of Energy
Abstract
Pedagogically speaking, the formulation of the first law of thermodynamics is
the real beginning of the study of heat and energy. Rejecting caloric’s
materiality, the mechanical equivalent of heat proved that heat can be measured
in terms of mechanical energy and the heat—mechanical energy equivalence led
to the first law (the energy conservation principle) and that heat is a form of
energy, the lowest-grade form of energy. The conservation principle infers that
energy can be neither created nor destroyed, thus, only its form can be
transformed. This conceptual understanding and the application of dU ¼
dQ À pdV for thermodynamic processes are two key takeaways of this chapter.
The nature of the transformation of energy forms is the outstanding question
remaining for further investigation.
Keywords
Adiabatic work Á Internal energy Á Mechanical equivalent of heat (MEH) Á The
MEH constant (J) Á Conceptual differentiation of caloric Á The first law of
thermodynamics Á Heat versus heat Á Enthalpy Á Heat capacities Á Caloric
equation of state for ideal gases Á Polytropic processes of ideal gases
3.1 Introduction
With the successful determination of c p À c V and the success of the theory of
adiabatic heating, the caloric theory was showing itself to be a powerful instrument
indeed! Just at this point, the scientific tide began to turn against the Laplacian
orthodoxy. The dynamical theory of heat, an older but at that point a less developed
theory of heat, was making a comeback to challenge the caloric theory as part of the
anti-Laplacian movement.
© Springer Nature Switzerland AG 2020
L.-S. Wang, A Treatise of Heat and Energy, Mechanical Engineering Series,
https://doi.org/10.1007/978-3-030-05746-6_3
37