摘要:

A simple mathematical analysis using the shadow method is used to predict the shape, disposition, and spacing of moiré fringes produced by two parallel-line grids. The method is extended to grids of regularly spaced closed-nested-plane figures and then to repeated cell structures. Generalizing, it is shown that for any species of grid “moiré magnification” results. The linear and angular displacements of the fringes are related to the relative rotation and displacement of the grids to show the applicability of moiré fringes as a sensitive tool for positioning or for measuring very small displacements and rotations. A brief discussion is presented of the use of the phenomenon as a visual aid in the classroom.

ISSN:0002-9505    

DOI:10.1119/1.1970239

出版商:American Association of Physics Teachers    

年代:1964

数据来源: AIP

摘要:

It is suggested that students would not be so careless about significant figures if they could actually see a demonstration of figures which are not significant. Such a demonstration is described, as is a simple teaching machine designed to give students facility in identifying insignificant figures in their calculations.

ISSN:0002-9505    

DOI:10.1119/1.1970241

出版商:American Association of Physics Teachers    

年代:1964

数据来源: AIP

摘要:

The Lorentz-transformation equations are derived, with the aid of elementary calculus, from the basic kinematical assumptions of special relativity without the use of any linearity assumption.

ISSN:0002-9505    

DOI:10.1119/1.1970244

出版商:American Association of Physics Teachers    

年代:1964

数据来源: AIP

摘要:

A successful Laboratory-Techniques course, consisting of about 80 h in the workshop and laboratory, is outlined. The course is suitable for Pass and Honors physics students in their junior year.

ISSN:0002-9505    

DOI:10.1119/1.1970247

出版商:American Association of Physics Teachers    

年代:1964

数据来源: AIP

摘要:

With simple tools and with a minimum of manual dexterity, the cost of a physical pendulum experiment with a set of rings sold commerically for nearly $100, can be reduced to pennies by making use of bits of copper wire and squares cut principally from galvanized sheet metal scrap.

ISSN:0002-9505    

DOI:10.1119/1.1970251

出版商:American Association of Physics Teachers    

年代:1964

数据来源: AIP

摘要:

This article attempts to present a modern viewpoint of solids from an elementary and yet fundamental point of view. The unifying concept used is that of the “particles” of solid-state physics. Electrons (with spin), holes, phonons, plasmons, and magnons are discussed. The interaction of these particles is discussed in experiments involving light absorption, x rays, magnetic resonance, the Mössbauer effect, neutron scattering, electron beams, charge and heat transport, and acoustic absorption.

ISSN:0002-9505    

DOI:10.1119/1.1970253

出版商:American Association of Physics Teachers    

年代:1964

数据来源: AIP

摘要:

A coordinate transformation from a one-dimensional inertial frame of reference to an accelerated one in empty space-time has recently been proposed by Lass. His derivation displays the remarkable feature that the motion of the accelerated frame relative to the inertial frame is fully determined by a set of assumptions, none of which implies any requirement regarding the individual motions of the different points of one frame relative to the other frame. This peculiarity is ascribed to the conjunction of several independent constraints imposed on the mutual relative motions of such points among themselves. The properties involved in Lass' transformation are analyzed, and their mutual implications are studied. It is found that one property (namely, that the speed of light with respect to the noninertial frame, at each point of this frame and in both directions, is time-independent) has a special status. A comment is made regarding the extension of the transformation to a three-dimensional system.

ISSN:0002-9505    

DOI:10.1119/1.1970257

出版商:American Association of Physics Teachers    

年代:1964

数据来源: AIP

摘要:

During the year 1964 there are major anniversaries of the birth or death of eleven men whose accomplishments and influence have been of importance to the development of physics. They are: Joseph Sweetman Ames; Anders Jonas Ångström; Galileo Galilei; Julius Robert von Mayer; Hermann Walther Nernst; Nicolaus de Cusa; Denis Papin; Benjamin Thompson, Count Rumford; Benjamin Silliman, Sr.; Wilhelm C. W. O. F. F. Wien; and John Winthrop. Brief accounts of their achievements and lives are given here.

ISSN:0002-9505    

DOI:10.1119/1.1970260

出版商:American Association of Physics Teachers    

年代:1964

数据来源: AIP

摘要:

An approximate solution of the Navier-Stokes equation is given for incompressible flow through the thin annular gap beneath an air-supported puck. Expressions are derived which relate the pressure in the air film to the weight and dimensions of the puck, the thickness of the film to the total air flow, and the retarding force to the speed of a moving puck.

ISSN:0002-9505    

DOI:10.1119/1.1970264

出版商:American Association of Physics Teachers    

年代:1964

数据来源: AIP

摘要:

A number of writers on history of science have made it clear that in using the term “motive force” in the “Principia,” Newton referred to what we now call “impulse.” With this interpretation, there is a simple and plausible connection between the laws of impact as they were known and described in Newton's day and Newton's formulation of the Laws of Motion in the “Principia,” and we speculate that Newton might have been motivated by such a perception.

ISSN:0002-9505    

DOI:10.1119/1.1970268

出版商:American Association of Physics Teachers    

年代:1964

数据来源: AIP