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The principle of conservation of energy tells us that ‘energy can neither be created nor destroyed but only transformed’. The validity of the principle is without question. The problem is the concept. Contemporary physicists have asserted that we do not know what energy is. We find, however, 19th century physicists, contemporary physicists and historians of science who converge on the point: Mayer and Joule discovered energy. Therefore, we do not know what energy is, but we know these authors discovered it. What did they then discover? What can we learn from this with regard to the energy concept problem? To deal with this issue, I will distinguish between what the authors did experimentally and what they said about the phenomena. This method of analysis makes the difference in relation to historical works on the subject. In a second step, I will consider the introduction of the energy concept, which is from 1850s, and the reification of the energy in 1880s. Finally, I will address the energy conservation principle and the concept of energy conveyed by this principle in contemporary textbooks. As we shall see, the conservation of a magnitude that we call energy nowadays was discovered by Mayer and Joule; an indestructible and transformable entity was not. Adopting the original conservation principle would be enough to avoid the energy concept problem.

Philosophers have disagreed on the composition of force for decades. The main divergence concerns the fundamental question: given a certain motion that is observable, which force or forces are present in it, component or resultant forces? The present paper focuses on the conditions for dealing with this problem. I will argue that we are not able to infer force from the observation of a motion, as required by the problem. I will further argue that the validity of the Newtonian algorithm is not a sufficient condition for that inference because the Gaussian algorithm, which is equally valid, differs from the former with regard to the forces present in motions. Under these circumstances, I will make recourse to an experiment available in physics in which the force present in a motion is measured. Thus, we obtain a numerical value for this force. This result, playing the role of a counterexample, clarifies the composition of force issue significantly.

The present comment on Solari and Natiello’s paper (Found. Sci. 2019) values their constructivist approach to Newtonian Mechanics. My critical point concerns only the link between the concept of force and phenomena. It will be shown that the idealised form of the law of inertia created by the authors avoids criticism of the law and that this law (idealised or not) leads to the concept of force as the cause of acceleration. This concept appears in the authors’ reconstruction as an assumption. They add that this assumption must be contrasted with experiments. Following this, I address an experiment, in which the force that is taken as the cause of acceleration, is not present in the phenomenon at stake. As it thus does not satisfy the property of locality, which any cause has to, force cannot be a cause.

We learned at high school and university that Newton’s second law is $$F=ma$$ . However, Newton never wrote this equation. Furthermore, there is no agreement among historians of science as to the equation that expresses Newton’s second law. On the other hand, Euler claimed to have discovered a principle of mechanics, which is $$F=ma$$ . The respective paper of Euler provides us with the means of clarifying the issue. We can compare Newton’s second law and Euler’s principle with each other and verify whether there are significant differences between both laws. This is the task of the present paper. The result is that Newton’s axiomatic system and technique of decomposing force differ from Euler’s.

Poggendorff showed experimentally, in the middle of the 19th century, that the weight of an Atwood machine is reduced when it is brought to motion. His experiment has been revisited from time to time, making use of instrumentation that reflects the technological development of the moment. In this paper, the evolution of the experiment is briefly overviewed and a modern version of it, using a widespread commercial measurement system, is presented. The relevance of the ideas underlying the Poggendorff experiment for undergraduate physics teaching is also pointed out.

There has been much research on Schrodinger's route to what we now call Schrodinger's equation. Various authors disagree as to the exact nature of the influence of each of the physicists he cites—and of some that he does not. This paper, intended for graduate students of and researchers in quantum theory, clarifies Schrodinger's original aims in formulating a wave equation for matter, discusses how far he fulfilled his original aspirations and in what respects he fell short of his goal. An analysis of Schrodinger's foundational paper enables us to distinguish between a formal and an epistemological part, and consider the input of the physicists cited on the basis of the part in which each reference occurs. It turns out, for instance, that Hamilton's optical-mechanical analogy belongs entirely to the epistemological part. Indeed, no element of this analogy plays any role in the formal part of Schrodinger's argument. Instead of basing his theory on this analogy, as is often done nowadays in the physics literature and even in the history of science, we maintain that the aim of Schrodinger's project was to represent wave phenomena by a ‘wave’ in configuration- or q-space, paralleling Hertz's treatment in his Mechanics (1894). The influence of this book on Schrodinger's foundational paper is demonstrated by an analysis of his unpublished paper: Hertz's Mechanics and Einstein's Theory of Gravitation. This approach enables us to dispense with the optical-mechanical analogy in tracing the route to Schrodinger's equation. We also discuss the curious role of the Van Vleck determinant as the ‘missing link’ in taking the classical limit of Schrodinger's wavefunction. A concluding section discusses the relation of some of Schrodinger's earlier and later work to the development of quantum field theory.

The present paper accounts for progress in physics teaching in the sense that a problem, which has been closed to students for being too difficult, is gained for the high school curriculum. This problem is the compound Atwood machine with three bodies. Its introduction into high school classes is based on a recent study on the weighing of an Atwood machine.