ISSN:0002-9505    

DOI:10.1119/1.12618

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

摘要:

A one‐dimensional model of an ideal gas is proposed in order to study the development of disordered motion in Newtonian mechanics. A Monte Carlo procedure for the simulation of the statistical ensemble of an ideal gas with fixed total energy is developed. The comparison of both approaches is utilized for a pseudoexperimental foundation of statistical mechanics. The theoretical prediction of the Maxwell–Boltzmann distribution is derived from the Monte Carlo procedure.

ISSN:0002-9505    

DOI:10.1119/1.12620

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

摘要:

The properties of differentially rotating, completely degenerate sections of infinite cylinders are examined. Their construction is simple, with variables depending only on the radial cylindrical coordinate. They are found to possess important characteristics which qualitatively resemble much more complicated two‐dimensional models of differentially rotating degenerate stars: (1) an analog of the Chandrasekhar limit; (2) a limit to uniform rotation imposed by centrifugal breakup; (3) massive, differentially rotating structures of moderate radius can be constructed; and (4) models obey the Solberg–Ho/iland criterion for stability of the rotation field and appear to be stable against inverse beta decay and general relativistic collapse. These characteristics combined with the simplicity of construction make these models useful in the study of the structure and evolution of differentially rotating stars.

ISSN:0002-9505    

DOI:10.1119/1.12621

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

摘要:

The power expenditure in walking is presented as the sum of the work required for accelerating and decelerating the legs, plus the gravitational work associated to the lift of the trunk at each step. These two contributions are, respectively, inversely and directly proportional to pace length. As a consequence this model predicts an optimal pace, for a given speed, which corresponds to minimal power demand. This is in agreement with experiments on subjects walking on a treadmill. The model is primarily of pedagogical interest and its quantitative predictions not very accurate.

ISSN:0002-9505    

DOI:10.1119/1.12622

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

摘要:

Introducing a four‐vector strain and a four‐force stress, Hooke’s law is written as a four‐vector equation. This formulation is shown to clarify seemingly paradoxical results in connection with uniformly accelerated motion, and rotational motion with angular acceleration.

ISSN:0002-9505    

DOI:10.1119/1.12623

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

摘要:

It is shown how a simple electrical circuit may be made to operate as an impulsively excited damped harmonic oscillator having independently variable natural frequency and damping. The oscillator’s response is developed in a particularly transparent way through impulse analysis, a technique that is wholly within the time domain and provides an alternative to Fourier analysis in the frequency domain. Resonance is exhibited and interpreted using impulse analysis, and through resonance, contact is made with Fourier analysis.

ISSN:0002-9505    

DOI:10.1119/1.12624

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

摘要:

Starting from the energy and degeneracy of the Landau levels of a free‐electron gas in a magnetic field, the nonoscillatory term of the Landau diamagnetism is derived forT=0, using elementary algebra only.

ISSN:0002-9505    

DOI:10.1119/1.12607

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

摘要:

We show that the observed path of a particle in quantum mechanics is a fractal curve with Hausdorff dimension two.

ISSN:0002-9505    

DOI:10.1119/1.12657

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

摘要:

When dealing with the topic of finite conjugate, point‐source resolution in elementary discussions, we generally take one of two courses. Either we adopt the (somewhat unmotivated) standard Jenkins and White approach or else we try to derive the result on the basis of standard diffraction theory using the known result for the diffraction by a circular aperture. However, the Jenkins and White approach, while giving a believable resolution formula, implies a magnification formula which appears to be wrong. On the other hand, the diffraction approach gives the ’’correct’’ magnification formula but its resolution formula implies that infinite resolution is possible for finite wavelength light since the diffraction angle goes to zero for large apertures. It is shown that the key to a coherent presentation of this topic and the resolution of these difficulties is provided by the relatively obscure Abbe’s sine theorem.

ISSN:0002-9505    

DOI:10.1119/1.12658

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP

摘要:

Some simple undergraduate laboratory experiments are described, which verify the energy–momentum relationship of special relativity. These experiments have been designed either to be used as classroom demonstrations or to be carried out by second‐year students.

ISSN:0002-9505    

DOI:10.1119/1.12659

出版商:American Association of Physics Teachers    

年代:1981

数据来源: AIP