ISSN:0002-9505    

DOI:10.1119/1.15052

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.15054

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.15056

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

摘要:

This Resource Letter provides an introduction to the literature on the history of physics. Because of the overwhelming quantity of publications, the emphasis is on works covering broad topics and historical periods rather than on monographs dealing with special subjects or individual physicists, and on recent reference works that facilitate retrieval of more specialized information. The letter E after an item indicates elementary level or material of general interest to persons becoming informed in the field. The letter I, for intermediate level, indicates material of somewhat more specialized nature; and the letter A indicates rather specialized or advanced material. An asterisk (*) indicates those articles to be included in an accompanying Reprint Book.

ISSN:0002-9505    

DOI:10.1119/1.15057

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

摘要:

There has recently been a considerable growth in research probing student understanding in mechanics. Questions based on four such research probes were included in the end‐of‐high‐school physics examination undertaken by some 5500 students. The results obtained give an indication of the extent to which various interpretations of some physical situations are held in a whole population. The possibilities of using research probes as a basis for assessment questions are also illustrated.

ISSN:0002-9505    

DOI:10.1119/1.15058

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

摘要:

Special relativity demands a locality principle (no instantaneous action at a distance); locality implies Bell’s theorem; quantum mechanics violates Bell’s inequality, therefore, quantum mechanics contradicts relativity! Or so it would seem. It is shown, however, that the locality principle needed for Bell’s theorem is stronger than the simple locality that is needed to satisfy the demands of relativity and that quantum mechanics satisfies the latter. The stronger locality principle is equivalent to the conjunction of simple locality and predictive completeness, and it is the latter principle that fails. The notion of predictive completeness is weaker than, and is implied by, the completeness criterion of Einstein, Podolsky, and Rosen. But the quantum mechanical state description is not only incomplete but incompletable, for any local complete state description would satisfy Bell’s inequality and disagree with experiment.

ISSN:0002-9505    

DOI:10.1119/1.15059

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

摘要:

The maximum work obtainable from a finite heat source and finite heat sink, initially at respective temperaturesT+andT−, is determined as a function of the temperature ratio τ=T−/T+and the heat capacities of the source and sink. The thermal efficiency with which this work is delivered is found to be well approximated by η*=1−τ1/2for τ≥0.1, independent of the source and sink heat capacities. It is noted that η* occurs in other contexts for which work or power output is optimized, and is a surprisingly ‘‘universal’’ efficiency. A reversible polycycle that delivers the maximum work using an ideal gas working fluid is found to exist only if the heat capacity of the heat sink exceeds that of the working fluid. An example of a finite source/sink combination from which work can be generated is an enclosed gas, divided in half by a partition with a small, controllable trap door operated by a Maxwell’s demon. If the demon opens and closes the door selectively, so as to achieve a temperature difference across the partition, the analysis here enables an estimate of the subsequent maximum work that can be generated and the efficiency of this generation. Numerical estimates show that, as might be expected, such a demon is a rather ineffective work producer.

ISSN:0002-9505    

DOI:10.1119/1.15060

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

摘要:

How can the Newtonian gravitational constantGat the 0.1% accuracy level be measured in a student experiment? This article may help the reader in answering this question. The described improvements of a preexisting apparatus should be applicable to most student laboratories. Results based on direct deflection and swing‐time methods are presented. The corresponding sources of uncertainty and possible systematic errors are discussed.

ISSN:0002-9505    

DOI:10.1119/1.15061

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

摘要:

Heinrich Hertz, the discoverer of radio‐frequency electromagnetic radiation, also made important contributions to our knowledge of the photoelectric effect, cathode rays, electromagnetic theory, classical mechanics, and meteorology. In 1878 Hertz enrolled at the University of Berlin to study physics under Professor Hermann von Helmholtz. For the rest of his life he maintained a very close personal and scientific relationship with his mentor. The influence of Helmholtz on Hertz’s choice of research topics and on the kind of physicist Hertz became is documented from the writings of these two famous physicists.

ISSN:0002-9505    

DOI:10.1119/1.15062

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

摘要:

Those oscillatory motions for which the period is independent of the total energy are investigated. There is only one correspondingsymmetricpotential, the quadratic potential of the simple harmonic motion but infinite classes ofasymmetricpotentials must be considered. Geometric and analytic requirements of isochronism are discussed and several specific examples are given.

ISSN:0002-9505    

DOI:10.1119/1.15063

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP