摘要:

The question is asked whether, as is often claimed, the Lagrangian formulation of a physical theory provides its mechanical interpretation. For purposes of this enquiry, an analysis of physical theories is performed, with special emphasis on classical mechanics, electromagnetism, and quantum mechanics. Three aspects are distinguished and defined: the formulation (statement), the representation (transformation properties), and the interpretation (meaning). Confusion of formalism with meaning is criticized, and is suggested as a source of some misunderstandings of recent reinterpretations of quantum mechanics. Properties and advantages of Lagrangian formulations are listed, and it is recalled that their chief usefulness lies in that they are the most helpful precisely when mechanisms are either ignored or absent. It is concluded that Lagrangian formulations contribute to the demechanization of physics and that the program of reduction to mechanics has not succeeded in physics.

ISSN:0002-9505    

DOI:10.1119/1.1934403

出版商:American Association of Physics Teachers    

年代:1957

数据来源: AIP

摘要:

This paper is a review of three generalizations of the classical virial theorem of Clausius, the first to a continuous distribution of charge and mass moving with relativistic velocity and its associated electromagnetic field, the second to a single Dirac particle in an external electromagnetic field, and the third to a quantum-mechanical system of particles in a box. Various limiting cases are discussed and tensor versions of the theorem are given where applicable.

ISSN:0002-9505    

DOI:10.1119/1.1934404

出版商:American Association of Physics Teachers    

年代:1957

数据来源: AIP

摘要:

The recent English translation of Maurolico'sPhotismimisinterpreted the title of that work and mistook its date of composition.

ISSN:0002-9505    

DOI:10.1119/1.1934405

出版商:American Association of Physics Teachers    

年代:1957

数据来源: AIP

摘要:

This paper presents a method of solving certain differential equations of physics in a manner that aids the physics student to grasp the relationships between several of the functions with which he is already familiar. The method of making the relationships apparent is based on the use ofoneprocedure for deriving the circular functions, hyperbolic functions, and elliptical functions as well as others that are less common. While the method herein presented has a certain amount of generality, it is restricted to various types of force functions and does not include friction, induction, or driving forces. The physical illustration is a single vibrating mass and no discussion is given of vibrating strings or membranes.

ISSN:0002-9505    

DOI:10.1119/1.1934406

出版商:American Association of Physics Teachers    

年代:1957

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.1934407

出版商:American Association of Physics Teachers    

年代:1957

数据来源: AIP

摘要:

This second part carries on with the principles illustrated in Part I. Again nothing new is presented except a unified viewpoint. Three main subjects are discussed: A. Nonperiodic systems; B. The restoring force as a power series in ψ; and C. Methods for testing the validity of a solution. The discussion leads to interesting and familiar subjects such as hyperbolic and elliptical functions.

ISSN:0002-9505    

DOI:10.1119/1.1934408

出版商:American Association of Physics Teachers    

年代:1957

数据来源: AIP

摘要:

The famous exchange forces arise in quantum mechanics from the uncertainty at any given time as to which of the two potential wells a particle, which is capable of leaking back and forth between the two wells, is occupying. This entirely quantum-theoretical result can be given an energetic explanation, and in fact be estimated quantitatively, by finding the possible energy eigenfunctions for the particle, which correspond to nearly-equal or to nearly-opposite probability amplitudes for the wave function in each of the two wells. The variation of system energy with the separation of the wells can be interpreted as a force. The present paper is an effort to give a much more intuitive account of the origin of these important forces. The force is here interpreted purely kinematically as the result of the fact that the particle bombards the well edges both from within and from without. The net attractive or repulsive force between the wells then arises from the fact that for one type of wave function the bombardment is more frequent on the inner, facing edges, and so the wells are forced together, and conversely for the other type. The ideas are generalized to wells other than the idealized square potential well, and compared quantitatively with more familiar treatments of the problem.

ISSN:0002-9505    

DOI:10.1119/1.1934409

出版商:American Association of Physics Teachers    

年代:1957

数据来源: AIP

摘要:

A simple method is presented whereby the resultant of a set of vectors in a plane may be determined or checked by locating the centroid of the starting points of the vectors and the centroid of their endpoints.

ISSN:0002-9505    

DOI:10.1119/1.1934411

出版商:American Association of Physics Teachers    

年代:1957

数据来源: AIP

摘要:

The integral form of the conservation of energy for a continuous medium in motion is derived from the usual differential expression of the first law of thermodynamics. Various special cases of this relation are considered, and in particular it is shown that the invariance of the sum of kinetic energy, potential energy, ande+p̄/ρmay be written for arbitrary dissipative motions under certain definitions of the boundary conditions of the system.

ISSN:0002-9505    

DOI:10.1119/1.1934412

出版商:American Association of Physics Teachers    

年代:1957

数据来源: AIP

摘要:

A report is made on an upper-divison course in physics especially designed for secondary school teachers, given during the summer session of 1956 at the University of New Mexico. Both lecture and laboratory procedures are discussed.

ISSN:0002-9505    

DOI:10.1119/1.1934413

出版商:American Association of Physics Teachers    

年代:1957

数据来源: AIP