The Ideas of Work and Energy in Mechanics
It is difficult to trace the history of most physical concepts. This is also true for the concepts of work and energy. One line of investigation has been the process of the invention and construction of machines. In different ages, machines and devices in
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The Ideas of Work and Energy in Mechanics
The history of science offers no more surprising case than the phenomenon of simultaneous discovery. We have already named twelve members of the scientific community, each of whom, within a brief period, independently reached the essentials concerning the concepts of energy and its conservation. This list could be extended, in vain, however. This multiplicity already sufficiently suggests that in the two decades prior to 1850 the climate of European scientific thought contained elements capable of guiding receptive scientists to a significant new point of view about nature. (KUHN, Thomas S. La Tension Esencial. México: Fondo de Cultura Editores, 1996)
3.1 General Considerations It is difficult to trace the history of most physical concepts. This is also true for the concepts of work and energy. One line of investigation has been the process of the invention and construction of machines. In different ages, machines and devices invented to save work have always been researched for a variety of aims. Depending on the age in which the machines, mechanisms and devices were investigated, they have even been seen as associated with magic, due to the sometimes spectacular effects they produced. Since early times, inventors of machines have also realised that the mechanical benefits they offer, have often been accompanied or offset by disadvantages, as a kind of price paid to nature, since she gives nothing for free (Lindsay 1975). For a long time it has also been known that it is possible to lift a weight through a system of pulleys with much less effort than would be needed to lift it directly. Furthermore, it became evident that the speed of the cable which operated the whole system was much greater than the speed at which the weight was being lifted at the other end of the pulley system. Hence, if the system were operated at low speed, the time required to lift the weight would be excessively long. A. R. E. Oliveira, A History of the Work Concept, History of Mechanism and Machine Science 24, DOI: 10.1007/978-94-007-7705-7_3, © Springer Science+Business Media Dordrecht 2014
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3 The Ideas of Work and Energy in Mechanics
These facts were already known to Heron of Alexandria around 60 AD.1 This principle, developed throughout history, that the gains obtained by the use of machines were offset by certain disadvantages or losses, contained within it the germ of the concept of energy. In a more subtle way, it was also implicit that inherent to the working of the system, which involved gains and losses or advantages and disadvantages, something must remain constant. And this quantity which remained constant with the system working and which would only be revealed in the middle of the nineteenth century was precisely energy. Evidently we are talking about a system, that is, an idealized machine, in which all its parts comprise rigid elements, its surfaces completely smooth and working without impacts, etc. In reality, as we know, with a working machine part of the energy use
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