ISSN:0002-9505    

DOI:10.1119/1.11755

出版商:American Association of Physics Teachers    

年代:1979

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.11753

出版商:American Association of Physics Teachers    

年代:1979

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.11757

出版商:American Association of Physics Teachers    

年代:1979

数据来源: AIP

摘要:

The issue of observability and the relative roles of the senses and reason in understanding the world is reviewed. Eastern ’’mystical’’ philosophy is used as a focus in which interpretations of quantum mechanics, as well as the current bootstrap‐quark controversy, can be seen in some slightly different contexts than usual.

ISSN:0002-9505    

DOI:10.1119/1.11758

出版商:American Association of Physics Teachers    

年代:1979

数据来源: AIP

摘要:

No. However, divers and trampolinists can perform somersaults and twists even though they have zero angular momentum at all times during the stunt. Also, if a diver is somersaulting in space and possesses angular momentum only about his somersaulting axis, he can make a single discrete change in the position of his arms which initiates continuous twisting motion even in the absence of any applied torque. These apparent paradoxes have confused both physicists and coaches for some time. The present paper attempts to reduce this confusion. It discusses several different methods that performers use to initiate somersaults and twists and presents concrete examples of each method. Wherever possible quantitative calculations are presented and evaluated using information about the moments of inertia, mass, etc., of ’’typical’’ performers.

ISSN:0002-9505    

DOI:10.1119/1.11759

出版商:American Association of Physics Teachers    

年代:1979

数据来源: AIP

摘要:

A resonance apparatus for the measurement ofCp/Cvfor different gases is described. In the apparatus a magnetically supported piston in a vertical cylindrical glass tube containing the gas is forced into oscillation by means of a standard audio signal generator. The apparatus is simple and inexpensive, and may be used for general work on forced oscillations and resonance.

ISSN:0002-9505    

DOI:10.1119/1.11760

出版商:American Association of Physics Teachers    

年代:1979

数据来源: AIP

摘要:

Using a photon‐counting technique, we find the angular distribution of emitted and detected power and the total radiated power of an arbitrary moving source. We compare these expressions to the incorrect or incomplete expressions previously reported. We use the technique to verify the predicted effect of the earth’s motion through the cosmic blackbody radiation.

ISSN:0002-9505    

DOI:10.1119/1.11762

出版商:American Association of Physics Teachers    

年代:1979

数据来源: AIP

摘要:

The use of biological examples in teaching applications of the analog computer is discussed. In an introductory general physics laboratory class which included biology majors, the addition of some biologically relevant analog computer problems was well received. The response indicates that such problems can be particularly useful in physics classes which include life‐science students or which explore biophysics topics. Several suitable examples from mathematical ecology, enzyme kinetics, and tracer dynamics are described.

ISSN:0002-9505    

DOI:10.1119/1.11765

出版商:American Association of Physics Teachers    

年代:1979

数据来源: AIP

摘要:

By applying perturbation theory to a highly simplified solar system, we find that the semimajor axis of the Earth’s orbit is secularly invariant, the square of the eccentricity varies approximately sinusoidally with a secular period of 93 000 years, and the perihelion precesses toward the northern summer solstice with a period of approximately 21 000 years relative to the moving vernal equinox. The Earth’s axis also nutates with a period of 41 000 years. These periods correlate very well with the periods found in the climatic record. The secular periods of the Earth’s orbital parameters determine the variation with time of the average intensity of solar radiation and thus may trigger the onset of ice ages.

ISSN:0002-9505    

DOI:10.1119/1.11766

出版商:American Association of Physics Teachers    

年代:1979

数据来源: AIP

摘要:

A Lagrangian that yields equations of motion for a damped simple harmonic oscillator is shown not to describe this system, but a completely different physical system. Thus, we have a simple counterexample to the statement: ’’If a Lagrangian gives the correct equations of motion for a given system then the Lagrangian describes the system.’’ We also construct a physical system that the Lagrangian describes and derive some of its properties. The quantum theory based on the above Lagrangian has been used to attempt to discuss the quantum theory of dissipation. This is, however, incorrect since the system the Lagrangian describes has no dissipation.

ISSN:0002-9505    

DOI:10.1119/1.11767

出版商:American Association of Physics Teachers    

年代:1979

数据来源: AIP