AAPT Logo
AJP Logo
 
   
 

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

May 1987

Volume 55, Issue 5, pp. 391-479

back to top
RSS Feeds

The current challenge: Introductory physics

Roger S. Jones

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 391

Full Text: | Download PDF

Abstract Unavailable
Show PACS
01.40.Di Course design and evaluation

On the introductory course

Robert E. Kennedy

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 391

Full Text: | Download PDF

Abstract Unavailable
Show PACS
01.40.Di Course design and evaluation

Coriolis and consolation

Jack Tessman

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 392

Full Text: | Download PDF

Abstract Unavailable
Show PACS
01.60.+q Biographies, tributes, personal notes, and obituaries
45.05.+x General theory of classical mechanics of discrete systems

About ‘‘perplex numbers’’

André Ronveaux

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 392 | Cited 1 time

Full Text: | Download PDF

Abstract Unavailable
Show PACS
02.10.De Algebraic structures and number theory
03.30.+p Special relativity

Comment on ‘‘A retrograde motion demonstration model’’ [Am. J. Phys. 54, 1021 (1986)]

Ronald Lane Reese

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 393

Full Text: | Download PDF

Abstract Unavailable
Show PACS
01.50.My Demonstration experiments and apparatus
07.10.-h Mechanical instruments and equipment
95.10.-a Fundamental astronomy
96.12.De Orbital and rotational dynamics
96.15.De Orbital and rotational dynamics

Counterfactual definitions and physical properties

Bernard d’Espagnat

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 393

Full Text: | Download PDF

Abstract Unavailable
Show PACS
03.65.Ta Foundations of quantum mechanics; measurement theory

Solenoids and the Aharonov–Bohm effect

N. Gauthier

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 393

Full Text: | Download PDF

Abstract Unavailable
Show PACS
41.20.Gz Magnetostatics; magnetic shielding, magnetic induction, boundary-value problems

On the velocity of light

Kenneth J. Epstein

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 393

Full Text: | Download PDF

Abstract Unavailable
Show PACS
04.20.Cv Fundamental problems and general formalism
06.20.Jr Determination of fundamental constants
back to top
RSS Feeds

Editorial: The fallacy of immediacy

John S. Rigden

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 395

Full Text: | Download PDF

Abstract Unavailable
Show PACS
01.40.G- Curricula and evaluation
back to top
RSS Feeds

The hydrogen atom in one dimension

R. E. Moss

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 397 | Cited 17 times

Full Text: | Download PDF

Show Abstract
The Schrödinger, Klein–Gordon, and Dirac equations for the hydrogen atom are solved in D dimensions, where D may be noninteger. For D=1 the nondegenerate ground state with infinite binding energy is obtained as a limit as D tends to 1 for the Schrödinger equation. The corresponding solution of the Klein–Gordon equation is shown to be unacceptable, contradicting previous work. Unexpectedly, no bound state solutions of the Dirac equation with D=1 are found at all. A few comments are made on the D=3 and 2 cases.
Show PACS
03.65.Ge Solutions of wave equations: bound states

Cosmic strings: Gravitation without local curvature

T. M. Helliwell and D. A. Konkowski

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 401 | Cited 3 times

Full Text: | Download PDF

Show Abstract
Cosmic strings are very long, thin structures which might stretch over vast reaches of the universe. If they exist, they would have been formed during phase transitions in the very early universe. The space‐time surrounding a straight cosmic string is flat but nontrivial: A two‐dimensional spatial section is a cone rather than a plane. This feature leads to unique gravitational effects. The flatness of the cone means that many of the gravitational effects can be understood with no mathematics beyond trigonometry. This includes the observational predictions of the double imaging of quasars and the truncation of the images of galaxies.
Show PACS
98.80.Bp Origin and formation of the Universe
98.80.Cq Particle-theory and field-theory models of the early Universe (including cosmic pancakes, cosmic strings, chaotic phenomena, inflationary universe, etc.)
95.30.Sf Relativity and gravitation

A conceptual approach to teaching kinematics

Mark L. Rosenquist and Lillian C. McDermott

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 407 | Cited 11 times

Full Text: | Download PDF

Show Abstract
Results from research on student understanding of velocity and acceleration have been used to guide the development of a conceptual approach to teaching kinematics. This paper describes how instruction based on the observation of actual motions can help students: (1) develop a qualitative understanding of velocity as a continuously varying quantity, of instantaneous velocity as a limit, and of uniform acceleration as the ratio of the change in instantaneous velocity to the elapsed time; (2) distinguish the concepts of position, velocity, change of velocity, and acceleration from one another; and (3) make connections among the various kinematical concepts, their graphical representations, and the motions of real objects. Instructional strategies designed to address specific difficulties identified in the investigation are illustrated by example.
Show PACS
01.40.G- Curricula and evaluation
45.05.+x General theory of classical mechanics of discrete systems

Rigid‐body dynamics of a football

Peter J. Brancazio

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 415 | Cited 2 times

Full Text: | Download PDF

Show Abstract
The motion of a spinning football provides interesting illustrations of some of the principles of rigid‐body motion. The familiar ‘‘wobbly spiral’’ is an example of torque‐free precession; it is shown that the ‘‘wobble‐to‐spin’’ ratio depends only on the principal moments of inertia of the football. The angular momentum of a spinning football is not always conserved in flight. The response of a football to aerodynamic forces can best be understood by comparing its motion to that of a spinning top or gyroscope.
Show PACS
45.05.+x General theory of classical mechanics of discrete systems

Magnetic force due to a current‐carrying wire: A paradox and its resolution

Denise C. Gabuzda

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 420 | Cited 4 times

Full Text: | Download PDF

Show Abstract
A straightforward investigation at an introductory level of the interconnection between electricity and magnetism initially leads to the paradoxical result that a charge at rest with respect to a current‐carrying wire feels a magnetic force due to that current. Students may benefit from a presentation of this paradox and its resolution.
Show PACS
41.20.Cv Electrostatics; Poisson and Laplace equations, boundary-value problems
41.20.Gz Magnetostatics; magnetic shielding, magnetic induction, boundary-value problems

Frequency‐dependent performance of a nonideal Carnot engine

E. Rebhan and B. Ahlborn

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 423 | Cited 9 times

Full Text: | Download PDF

Show Abstract
The average power output P, efficiency η′, and entropy production Ps have been determined as function of cycle frequency ν for a nonideal Carnot engine where the ratio r of the heat absorption time and heat rejection time can be varied and the heat is transferred by conduction into the working fluid. The power output has an optimum at the value r=(β/α)1/2, where α and β are the thermal conductances of the upper and lower isotherm, respectively. The efficiency decreases and the conduction losses increase drastically with cycle frequency. The power output goes through a maximum, peaked at a frequency ν∗. The efficiency can be increased without much sacrifice in power output if the engine is run below the frequency ν∗ (12% efficiency increase at 3% loss in power for ν=0.85ν∗). The entropy production grows approximately as Ps ∼ν2.
Show PACS
05.70.-a Thermodynamics

The black hole as a gravitational ‘‘lens’’

Hans C. Ohanian

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 428 | Cited 24 times

Full Text: | Download PDF

Show Abstract
We discuss the ‘‘images’’ formed when the light from a distant source suffers a large deflection in the intense gravitational field in the immediate vicinity of a Schwarzschild black hole. The light can circle around the black hole one or several times, and therefore give rise to a sequence of images. We show that the deflection angles and the intensities of the images can be expressed in terms of elliptic integrals, leading to simple approximations in the limiting case of very large deflection angles.
Show PACS
97.60.Lf Black holes
95.30.Sf Relativity and gravitation

Approximations for the range of ballistic missiles

Ralph Snyder

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 432 | Cited 1 time

Full Text: | Download PDF

Show Abstract
The actual range, flight time, and maximum height of an ICBM are compared to the predictions of five simple approximations that are more sophisticated than the standard flat‐Earth‐with‐constant‐gravity problem but more elementary than the full Keplerian solution. The simplest of these approximations is accessible to first‐year students and gives results in closed form whose range predictions are in good agreement with the Keplerian ranges at typical ICBM speeds.
Show PACS
45.05.+x General theory of classical mechanics of discrete systems

A simple geometrical model of spontaneous symmetry breaking

P. K. Aravind

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 437 | Cited 1 time

Full Text: | Download PDF

Show Abstract
A common, everyday phenomenon has a geometrical aspect that, in some respects, is analogous to a second‐order phase transition. Concepts such as spontaneous symmetry breaking, order parameter, critical point, and critical exponent can thus be exhibited in a purely geometrical context. The purpose of the model, which is entirely pedagogical, is to illustrate in an elementary and amusing way some of the concepts associated with phase transition theory.
Show PACS
05.70.Fh Phase transitions: general studies

Toward a modeling theory of physics instruction

David Hestenes

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 440 | Cited 31 times

Full Text: | Download PDF

Show Abstract
An analysis of the conceptual structure of physics identifies essential factual and procedural knowledge which is not explicitly formulated and taught in physics courses. It leads to the conclusion that mathematical modeling of the physical world should be the central theme of physics instruction. There are reasons to believe that traditional methods for teaching physics are inefficient and substantial improvements in instruction can be achieved by a vigorous program of pedagogical research and development.
Show PACS
01.40.G- Curricula and evaluation

Modeling instruction in mechanics

Ibrahim Abou Halloun and David Hestenes

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 455 | Cited 16 times

Full Text: | Download PDF

Show Abstract
Modeling theory was used in the design of a method to teach problem solving in introductory mechanics. A pedagogical experiment to evaluate the effectiveness of the method found positive results.
Show PACS
01.40.G- Curricula and evaluation
01.50.Kw Techniques of testing

Band structure of a periodic potential with two wells and two barriers per period

H. X. Jiang and J. Y. Lin

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 462 | Cited 3 times

Full Text: | Download PDF

Show Abstract
The energy bands of electrons in a one‐dimensional periodic potential consisting of two different rectangular barriers and wells per period are calculated. The variation of the energy band structure as a function of the size of the wells in each period is presented. The results can be used to obtain the energy scheme of a superlattice with the layer structure of this model. The method used can be applied to solve for the band structure of an electron in a periodic potential consisting of multiple barriers per period.
Show PACS
71.15.-m Methods of electronic structure calculations
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Quantum and classical electrons in a potential well with uniform electric field

D. Nguyen and T. Odagaki

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 466 | Cited 3 times

Full Text: | Download PDF

Show Abstract
We calculate the polarization of the quantum and classical electrons confined in a one‐dimensional infinite potential well in the presence of a static electric field. As the external field is increased, the polarization always increases for a quantum electron in the ground state, but the polarization of an electron in any excited state decreases for a weak field and increases after passing a minimum. The polarization of a classical electron with nonzero initial kinetic energy is similar to the response of a quantum electron in excited states. The polarization determined by the diffusion equation is similar to the polarization of a quantum electron in the ground state.
Show PACS
03.65.Ta Foundations of quantum mechanics; measurement theory
back to top
RSS Feeds

Comments on ‘‘Comments on ‘Fixed points in torque–angular momentum relations’ ’’ [Am. J. Phys. 53, 586 (1985)]

David J. McGill and John G. Papastavridis

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 470 | Cited 1 time

Full Text: | Download PDF

Abstract Unavailable
Show PACS
45.05.+x General theory of classical mechanics of discrete systems

The Poynting vector distribution in a simple transformer

N. Morton

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 472 | Cited 1 time

Full Text: | Download PDF

Abstract Unavailable
Show PACS
41.20.Gz Magnetostatics; magnetic shielding, magnetic induction, boundary-value problems
84.30.-r Electronic circuits

Comment on ‘‘The Poynting vector distribution in a simple transformer’’

Paul Lorrain

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 474

Full Text: | Download PDF

Abstract Unavailable
Show PACS
41.20.Gz Magnetostatics; magnetic shielding, magnetic induction, boundary-value problems
84.30.-r Electronic circuits

Comment on ‘‘The Poynting vector distribution in a simple transformer’’

William A. Newcomb

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 474

Full Text: | Download PDF

Abstract Unavailable
Show PACS
41.20.Gz Magnetostatics; magnetic shielding, magnetic induction, boundary-value problems
41.20.Cv Electrostatics; Poisson and Laplace equations, boundary-value problems
84.30.-r Electronic circuits

Charge distributions and coefficients of potential for a system of conductors in electrostatic equilibrium

M. I. Prieto and M. Quintillán

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 474

Full Text: | Download PDF

Abstract Unavailable
Show PACS
41.20.Cv Electrostatics; Poisson and Laplace equations, boundary-value problems
41.20.Gz Magnetostatics; magnetic shielding, magnetic induction, boundary-value problems

Response to ‘‘Charge distributions and coefficients of potential for a system of conductors in electrostatic equilibrium’’

Roald K. Wangsness

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 475

Full Text: | Download PDF

Abstract Unavailable
Show PACS
41.20.Cv Electrostatics; Poisson and Laplace equations, boundary-value problems
41.20.Gz Magnetostatics; magnetic shielding, magnetic induction, boundary-value problems

A close look at a canonical semiclassical derivation of the gravitational red shift

Jeff Goldstein

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 476

Full Text: | Download PDF

Abstract Unavailable
Show PACS
04.40.-b Self-gravitating systems; continuous media and classical fields in curved spacetime

Derivation of the one‐dimensional wave equation

N. Gauthier

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 477

Full Text: | Download PDF

Abstract Unavailable
Show PACS
41.20.Jb Electromagnetic wave propagation; radiowave propagation
02.30.Jr Partial differential equations
back to top
RSS Feeds

Quantum Reality: Beyond the New Physics

Nick Herbert, Author and Frederick M. Stein

American Journal of Physics -- May 1987 -- Volume 55, Issue 5, pp. 478

Full Text: | Download PDF

Abstract Unavailable
Show PACS
01.30.Ee Monographs and collections
03.65.Ta Foundations of quantum mechanics; measurement theory
Close

Your Recent History Recent History Help

Recently Viewed

  1. ‘‘Why Johnny can’t learn physics from textbooks I have known,’’ Mario Iona’s acceptance speech for t...
  2. Carnot’s function: Origins of the thermodynamic concept of temperature
  3. An investigation of student understanding of the real image formed by a converging lens or concave m...
  4. 1986 Richtmyer Lecture: Unification, grand unification, and the unity of physics
  5. Resource letter PS‐1: Physics of sports

AAPT on:

close