ISSN:0002-9505    

DOI:10.1119/1.16560

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.16561

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.16562

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

Many different solutions to the problem of the relativistic particle in a uniform gravitational field have been offered. The fact that different, apparently correct, solutions to the same problem exist is in itself a puzzle. A resolution to this puzzle is found by exploiting the equivalence principle to reduce the problem to the observations made by an accelerated observer of objects moving inertially in a background inertial frame. It is shown that some solutions, those arising from a truly curved space‐time, cannot be treated in this manner. It is found that differences in the remaining solutions arise because the authors use coordinate displacement to describe the motion rather than proper distance. The coordinate systems of these different accelerated frames are distorted and produce different apparent motions of objects in the background frame. When the ‘‘right’’ variables are used all motions are identical.

ISSN:0002-9505    

DOI:10.1119/1.16563

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

With the personal computer the undergraduate physics student can investigate interesting physical systems. This is illustrated with a study of golf drives predicted from experimentally measured lift and drag coefficients which give forces nearly proportional to the square of the velocity of the ball. Their interplay gives a surprising linear dependence of range on initial velocity, in good agreement with empirical formulas but in contrast with the quadratic dependence discussed in introductory physics courses. Spin damping is easily introduced and found to decrease the range for a given launch angle. The exploration of quantitative and qualitative differences between the trajectories produced by measured drag and lift forces and those predicted by a model with a linear velocity dependence illustrates the scientific method at work.

ISSN:0002-9505    

DOI:10.1119/1.16564

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

The Doppler formulas for sound waves are derived in a particularly simple way from a space‐time diagram. The method used emphasizes use of space‐time diagrams in a quantitative way.

ISSN:0002-9505    

DOI:10.1119/1.16565

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

The free oscillations of a chain of identical masses connected by identical springs can be very complicated, resembling the chaotic oscillations of nonlinear systems. These oscillations, however, differ in significant ways from chaotic oscillations. They are actually oscillations of a type called almost periodic that are also observed in nonlinear systems. This article solves the equations of motion for longitudinal oscillations in a finite linear chain. The resulting oscillations are discussed and compared with chaotic oscillations. The linear chain can easily be set up as a demonstration.

ISSN:0002-9505    

DOI:10.1119/1.16566

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

By approximating the scattering potential in thelth partial wave equation with a series of constant segments, an exact solution in terms of spherical Bessel and Neumann functions becomes available. Continuity at the segment boundaries is achieved with the aid of a simple 2×2 matrix formalism and leads to exact expressions for the scattering phase shifts.

ISSN:0002-9505    

DOI:10.1119/1.16567

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

The recent discovery of novel properties possessed by two‐dimensional systems has led to the investigation of properties of the hydrogen atom in two dimensions. With proper definition of the system, the so‐called Runge–Lenz vector may be defined for this system, and shown to be related to the underlyingO(3) symmetry, just as for the three‐dimensional system, although some interesting aspects are revealed.

ISSN:0002-9505    

DOI:10.1119/1.16568

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

In the evaluation of the magnetic fields produced by magnetized bodies in a vacuum the bodies can be replaced by fictitious ‘‘magnetization’’ currents. Therefore, it should be possible to calculate magnetic fields of real currents by replacing them with fictitious magnetized bodies. This possibility is explored in the present article. In one of the examples considered the net magnetic field due to a uniformly charged sphere spinning on its axis is calculated. Other applications are suggested.

ISSN:0002-9505    

DOI:10.1119/1.16569

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP