摘要:

The possibility of observing interference in ’’quantum magnification’’ experiments such as the celebrated ’’Schroedinger cat’’ is examined. Conditions on the size and complexity of systems for which interference may be reasonably sought are developed. The possibility of observing interference is used as a criterion for separating the realm of microscopic dynamics from the macroscopic. The dividing line is estimated to fall at system sizes of about 100 Daltons.

ISSN:0002-9505    

DOI:10.1119/1.10908

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

Cross sections, if defined in accordance with physical intuition, are projected areas, which should be subject to Lorentz contraction. The customary definition of cross sections, however, presumes that they are Lorentz invariant. An alternative, intuitive definition is presented.

ISSN:0002-9505    

DOI:10.1119/1.10909

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

The Fourier transformation which maps wave functions in the momentum representation into wave functions in the coordinate representation may be regarded as a 90° rotation in phase space. Starting from this observation we introduce continuously rotated wave functions. These rotated wave functions make it possible to define the expectation values of products of the formpkxnin an unambiguous way. The result is the same as that of the Wigner–Moyal formulation.

ISSN:0002-9505    

DOI:10.1119/1.10910

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

A consistent description and analysis of a martial arts demonstration is presented. The physics associated with striking and breaking a bone or a board is developed from an energy point of view.

ISSN:0002-9505    

DOI:10.1119/1.10911

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

A spring weight used as an accelerometer and as a dynamometer is considered. It is shown that in the theory of relativity the force scale of a dynamometer moving in a gravitational field is conventionally changed with position and velocity. Investigating the acceleration and weight of extended bodies, it is concluded that this weight does not depend on the position of the supporting force on the body. The connection between this result and the relativistic interpretation of the gravitational Doppler effect, which implies that from a global point of view the energy of a photon moving in a gravitational field is constant, is emphasized.

ISSN:0002-9505    

DOI:10.1119/1.10912

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

When does the Schrödinger equation have bound‐state solutions? This question is pursued by a variational method with simple trial wave functions. An arbitrary one‐ or two‐dimensional attractive potential is shown to have at least one discrete energy level, and estimates of the binding energy are obtained for shallow potential wells. In other problems, sufficient conditions are established for the existence of bound states.

ISSN:0002-9505    

DOI:10.1119/1.10913

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

The Lorentz–Dirac theory of radiation reaction on the motion of point charges is beset by the well known problems of runaway solutions and preacceleration. We examine the classical theory of extended charged particles and obtain a differential‐difference type equation of motion. Analysis of this equation reveals that the theory is internally consistent (i.e., no runaways or acausality) whenever the size of the particle exceeds the classical radius (defined as the radius for which the electrostatic self‐energy equals the mass of the particle). A specific example is presented which explicitly shows the different character of the extended and point charge solutions.

ISSN:0002-9505    

DOI:10.1119/1.10914

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

Recent advances in design of small programmable calculators have brought some important but previously impractical problems within range of such instruments. Procedures are described for doing Fourier analysis and synthesis with a Hewlett‐Packard HP‐25 calculator. Only one program is required for each operation. Both programs should be suitable for instructional use by physics, engineering, and mathematics students at a wide range of levels.

ISSN:0002-9505    

DOI:10.1119/1.10915

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

A college teacher’s verbal behavior can be measured. Types of classroom interaction can be tallied and analyzed, either by an observer in the classroom or by viewing and listening to video tapes. Observational systems such as Flanders’ Interaction Analysis Categories (FIAC) and the Florida Taxonomy of Cognitive Behavior (FTCB) can be used for verbal ratings. Teacher behavior can also be modified. When the teacher selects his own instructional goals or strategy, teaches, and then receives feedback on his performance, that performance can be modified or changed in future sessions. These are our conclusions based upon an experiment with videotaping and classroom verbal rating systems to induce more ’’higher level’’ questioning by instructors in introductory physics laboratories.

ISSN:0002-9505    

DOI:10.1119/1.10916

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.10917

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP