摘要:

A rough order‐of‐magnitude analysis is made of the equations of stellar structure. Analytic formulas are derived for the luminosity, radius, and mass as functions of the temperature. These formulas, while highly approximate, provide a simple, analytically tractable model of a star.

ISSN:0002-9505    

DOI:10.1119/1.14993

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

摘要:

Student understanding of the impulse‐momentum and work‐energy theorems was assessed by performance on tasks requiring the application of these relationships to the analysis of an actual motion. The participants in the study were undergraduates enrolled in either the honors section of a calculus‐based introductory physics course or in the regular algebra‐based course. The students were asked to compare the changes in momentum and kinetic energy of two frictionless dry‐ice pucks as they moved rectilinearly under the influence of the same constant force. The results of the investigation revealed that most of the students were unable to relate the algebraic formalism learned in class to the simple motion that they observed.

ISSN:0002-9505    

DOI:10.1119/1.14994

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

摘要:

Using a spreadsheet routine on a personal computer, we obtain solutions to Laplace’s equation quickly, even with dielectric interfaces present. This provides an alternative to solving electrostatics problems normally dealt with by relaxation methods infortranprograms or Fourier series solutions.

ISSN:0002-9505    

DOI:10.1119/1.14995

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

摘要:

The equipment and procedure needed to produce, view, and record good quality real‐time holographic interferograms in the undergraduate laboratory are described in step‐by‐step detail. Major concerns in the production, processing, and viewing are discussed further. Some investigations are suggested.

ISSN:0002-9505    

DOI:10.1119/1.14996

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

摘要:

Energy considerations give an incorrect value for the minimum height from which a sphere may be released on the approach track of a loop‐the‐loop, assuming that the sphere rolls without slipping. Analytical and graphical methods are described for predicting whether the sphere will negotiate the top of the circular loop for arbitrary conditions of release height and coefficients of friction. Finally, a situation in which a sphere commences to slip immediately upon release is discussed.

ISSN:0002-9505    

DOI:10.1119/1.14997

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

摘要:

Snell’s law of refraction is a conservation law of optical momentum. In infinitesimal form, it leads directly to the Hamilton equations for geometrical optics. The latter guarantee that the transformation of optical phase space produced by propagation through a medium where the index of refraction is continuously differentiable, is canonical. Discontinuous‐index systems such as refracting surfaces must be treated through a complementary description to show that they are also canonical. They have recently been shown to factorize into two ‘‘root’’ transformations, each depending on the properties of a single medium, and each canonical. This factorization is applicable to reflection off curved mirrors as well.

ISSN:0002-9505    

DOI:10.1119/1.14999

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

摘要:

A system for recording and analyzing optical diffraction patterns using a self‐scanning photodiode array interfaced to a popular microcomputer is described. The detector array consists of 128 photodiodes on 25‐μm centers and is sensitive to light in the visible portion of the spectrum. Details of the interface between the array and an Apple II microcomputer are given. The overall performance of the system is demonstrated for Fresnel diffraction by a single slit.

ISSN:0002-9505    

DOI:10.1119/1.15000

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

摘要:

We have generalized the unrestained brachistochrone problem to includerollingobjects in order to construct a demonstration brachistochrone track. Due to the nature of the constraints this well‐posed extremal problem cannot be solved using the techniques of Euler and Lagrange. The solution, parametrized by a measure of the generalized cylinder’s moment of inertia, reduces to that for the (sliding) unrestrained brachistochrone in the limit of vanishing moment of inertia.

ISSN:0002-9505    

DOI:10.1119/1.15001

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.15002

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.15010

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP