摘要:

Analysis of a forward karate punch is made as an example of collision mechanics. The energy lost to deformation of an opponent is evaluated, and the deformation is shown to be maximized if contact is made when the fist has the greatest speed. In karate fighting the maximum deformation is obtained by focusing a punch to terminate several centimeters inside an opponent’s body. The average impact force is calculated and compared with that neeeded to break a human bone by stressing it beyond its ultimate bending stress value. Similar breaking forces needed for bricks and wooden boards are also computed. A brief description of breaking demonstrations for the physics classroom is made.

ISSN:0002-9505    

DOI:10.1119/1.9966

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

More than 50 books and 14 periodicals published in 1973 have been analyzed for contributions to the history of physics. The subjects most frequently discussed were optics, ether, relativity, mechanics, and atomic or nuclear physics. A survey of this literature is presented in the form of a chronological review of relevant aspects of the history of physics, from Chinese optics in the 5th century B.C. to the discovery of parity nonconservation in the 20th century A.D. Brief comments are made on current controversies among historians of science, such as the significance of ’’anticipation’’ of modern ideas in the writings of earlier scientists, and the role of experiment in the work of Galileo and Einstein. The most important new publication by a single author is James Bell’sTheExperimentalFoundationsofSolidMechanics, a treatise which seems to have been ignored by most historians of physics.

ISSN:0002-9505    

DOI:10.1119/1.9967

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

The use of tensors for describing the physical properties of crystals is not particularly widespread in undergraduate curricula. Tensor concepts, however, are unavoidable in describing the properties of anisotropic media, of which crystals are a very important example. This paper describes suggested introductory material on tensors for use in an undergraduate materials science course. Special emphasis has been placed on communicating the basic tensor concepts through the use of examples. Mathematical manipulations have intentionally been minimized.

ISSN:0002-9505    

DOI:10.1119/1.9968

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

A consistent relativistic kinematic description of a rotating disk is given. The disk is described from the point of view of an inertial observer momentarily at rest relative to a point on the periphery of the disk, and as observed in a coordinate system SS′ rotating with the disk. The kinematic resolution of Ehrenfest’s paradox is stated. Also the following elements of the description are analyzed: (a) the transformation of time from an inertial system, where the axis of the disk is at rest, to SS′; (b) the spatial geometry in SS′; and (c) the velocity of light in SS′. The procedure for synchronization of the coordinate clocks on the disk is stated explicitly.

ISSN:0002-9505    

DOI:10.1119/1.9969

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

We present models of second‐order phase transitions, using elementary equipment, which reproduce the static behavior above a mean field phase transition and the thermodynamic slowing down on each side of it. The model is compared to continuum physics examples involving side effects in liquid crystals (Freedericksz transition) and in superconductors (proximity effect).

ISSN:0002-9505    

DOI:10.1119/1.9970

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

The multiphoton states of a thermal radiation field are studied by using elementary methods. The distribution of states and the degeneracy parameter are discussed.

ISSN:0002-9505    

DOI:10.1119/1.9971

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

Using a commercially available hydrogen–deuterium light source and a 3.4‐m Ebert plane grating spectrograph, the wavelengths of the first six pairs of the Balmer series are obtained. From the results, first, the series limit, Rydberg constant, and ionization potential of hydrogen are found from the graph. Then, by means of formulas involving wave numbers of hydrogen and deuterium and by knowing the Faraday constant, the values of m, e/m, and Mp/m are determined. All the values are found to be in good agreement with accepted values. From the results, this experiment is recommended for an upper division optics and spectroscopy or quantum physics laboratory.

ISSN:0002-9505    

DOI:10.1119/1.9972

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

In any method for quantitatively determining the Kerr constant of nitrobenzene, the question of the purity of the material cannot be ignored. In the method described, account is explicitly taken of the effect of impurity ions in the dielectric on the optical performance of the Kerr cell. Thus, although nitrobenzene of less than the highest attainable purity is employed, results comparable in accuracy to expert determinations of the Kerr constant are obtained. The method, therefore, offers possibilities for a student experiment. Details of cell construction, nitrobenzene purification, optical procedures, and data reduction are given. Also included is a general discussion of electrical effects and the electro‐optical effects in Kerr cells having dielectrics that are less‐than‐perfect electrical insulators.

ISSN:0002-9505    

DOI:10.1119/1.9973

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

A time‐tested program of interdisciplinary service courses at a small college is described. The program involves faculty from areas other than physics and has stabilized over a period of seven years at an academically successful level. Drawbacks as well as advantages of the program are described.

ISSN:0002-9505    

DOI:10.1119/1.9974

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

The PAiA 2720 Synthesizer, available in modular kit form, provides an easy and inexpensive way to do some demonstrations for physics of music courses that would be very difficult with conventional apparatus. The synthesis of sounds is discussed together with details of the PAiA. An inexpensive way to use a good oscilloscope to project waveforms is discussed, and ten demonstrations are suggested.

ISSN:0002-9505    

DOI:10.1119/1.9975

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP