摘要:

This article was published in 1971 in the Russian journalScienceandLife. Teachers and students who read our Journal can profit from the advice of this master theoretician. We are grateful to E. M. Lifshitz and the editor ofScienceandLifefor permission to publish the article and particularly to J. George Adashko for preparing the translation.

ISSN:0002-9505    

DOI:10.1119/1.10828

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

The simplest model of a black hole, the massive point source generating a static spherically symmetric gravitational field, is examined using the Schwarzschild coordinate frame. A brief review is given of this coordinate frame external to the Schwarzschild surface. Greater attention is paid to an interpretation of this frame inside the Schwarzschild surface. Here the roles of space and time are reversed in the sense that the external radial coordinate becomes an internal temporal coordinate, and the external temporal coordinate becomes an internal spatial coordinate. An internal universe is constructed from this frame, and a few simple kinematic phenomena are described in terms of it. The internal and external coordinates are connected graphically by using Kruskal coordinates and physically by considering the world lines of photons and freely moving particles which transit the Schwarzschild surface.

ISSN:0002-9505    

DOI:10.1119/1.10829

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

Two one‐quarter descriptive physics courses which have been particularly successful are described. Course content and teaching techniques are discussed. Resulting large enrollments and positive reception by students and faculty are reported.

ISSN:0002-9505    

DOI:10.1119/1.10830

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

Introductory physics homework problems done in conjunction with student‐performed demonstrations in the UC Santa Barbara Physics Learning Center are described and evaluated. These demonstration–problems presently supplement the standard textbook assignment for 370 students from our physics for engineers and scientists courses. Students find them more enjoyable than their textbook problems. We view them as valuable exercises within a process approach to instruction and consistent with the developmental theory of Jean Piaget. Arguments are given regarding their potential for promoting intellectual development. Other advantages are also cited.

ISSN:0002-9505    

DOI:10.1119/1.10831

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

We point out that the idea of confined quarks or partons as constituents of the elementary particles was already present in the Greek atomic theory. We describe some similarities and differences between ancient and modern confinement, and we suggest that in both cases the idea is in large part a response to an inherent conflict between the intuitive notion of infinite divisibility and the idea of discrete fundamental atoms of matter.

ISSN:0002-9505    

DOI:10.1119/1.10832

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

The slowing‐down distances and times of fast neutrons are calculated by extending the early work of Fermi to the case in which the neutron mean free path is energy dependent. This calculation is essentially a one‐particle Monte Carlo treatment in which each path length is a mean free path and the neutron is always scattered through a scattering angle ϑ, such that cosϑ=〈cosϑ〉, the average of cosϑ in the laboratory system. The average results derived by this analytic method are shown to be in reasonable agreement with a detailed Monte Carlo computer calculation of the moderation of a 1‐MeV neutron down to 40 eV in pure hydrogen. These calculations illustrate the Monte Carlo method and the broad spread in time and energy of the neutron flux resulting from an instantaneous point source in hydrogen. The results also graphically illustrate the greater penetrating distances of 14‐MeV neutrons compared to 1‐MeV neutrons in hydrogenous materials. Pedagogic, computer‐oriented uses of this material are suggested.

ISSN:0002-9505    

DOI:10.1119/1.10833

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

The radiometer is a commonly known toy that presents interesting features for scientific demonstrations in the field of the kinetic theory of rarefied gases. If a light beam is shined upon it, the radiometer starts moving in a manner that is, at first, quite unexpected. A simplified model is presented to illustrate its behavior in steady state operation. Some implications of the law of interaction between a rarefied gas and a solid surface are illustrated by the model.

ISSN:0002-9505    

DOI:10.1119/1.10834

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

A method is developed for treating successive rotations in terms of nonlinear products of rotation vectors. Combinations of ordinary scalar and vector products yield the same results that may be more commonly arrived at by the use of quaternions or 2×2 unitary matrices. The method automatically provides the direction of the axis and the value of the rotation angle of the single rotation that is equivalent to the product of two or more successive rotations. This information is not readily obtained from the usual matrix rotation method of solving the successive rotation problem. The method is applied to the case of a rotation about the [1 1 1] direction, successive π rotations about orthogonal axes, and the treatment of continuous rotations.

ISSN:0002-9505    

DOI:10.1119/1.10835

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

The analogs in two‐dimensional space of Bohr and Mottelson’s model can be used for the purpose of explaining simply the mathematics of nuclear collective motion, while conserving the essential physical ideas.

ISSN:0002-9505    

DOI:10.1119/1.10836

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

An interactive computer‐assisted linear least‐squares curve‐fitting program is described. The program consists of two parts. The first is designed for first users and, although it allows students to generate basic tables, plots, and fits to their data, it is primarily a teaching introduction to the more sophisticated second part. Linear functions of one or more variables with or without errors may be fitted to data, and very general data transformations are permitted. The program has been tested by over 600 first‐year physics students.

ISSN:0002-9505    

DOI:10.1119/1.10837

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP