AAPT Logo
AJP Logo
 
   
 

BROWSE VOLUMES

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

Jun 2009

Volume 77, Issue 6, pp. 487-576

back to top
RSS Feeds

WHOSE GOLDEN RULE IS IT ANYWAY?

Taco D. Visser

American Journal of Physics -- June 2009 -- Volume 77, Issue 6, pp. 487 | Cited 1 time

Online Publication Date: May 2009

Full Text: Read Online (HTML) | Download PDF

Abstract Unavailable
Show PACS
01.65.+g History of science
03.65.-w Quantum mechanics

BOHREN’S EDITORIAL

Ralph Baierlein

American Journal of Physics -- June 2009 -- Volume 77, Issue 6, pp. 487

Online Publication Date: May 2009

Full Text: Read Online (HTML) | Download PDF

Abstract Unavailable
Show PACS
01.65.+g History of science

REPEATED PROBLEM SOLVING REVISITED

Sergio Rojas

American Journal of Physics -- June 2009 -- Volume 77, Issue 6, pp. 487

Online Publication Date: May 2009

Full Text: Read Online (HTML) | Download PDF

Abstract Unavailable
Show PACS
01.40.Fk Research in physics education
back to top
RSS Feeds

The first frontier: High altitude ballooning as a platform for student research experiences in science and engineering

Shane L. Larson, John C. Armstrong, and William A. Hiscock

American Journal of Physics -- June 2009 -- Volume 77, Issue 6, pp. 489

Online Publication Date: May 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
High altitude balloon platforms are ideal for providing hands-on research experiences for students in physics, atmospheric science, engineering, and other aerospace-related disciplines. We describe a basic high altitude balloon platform that can be constructed and operated by undergraduate students. The existing HARBOR and BOREALIS programs are used to illustrate some possible science and engineering research projects that students can pursue as part of a high-altitude flight program.
Show PACS
01.50.Pa Laboratory experiments and apparatus
92.00.00 Hydrospheric and atmospheric geophysics

Gödel, Einstein, Mach, Gamow, and Lanczos: Gödel’s remarkable excursion into cosmology

Wolfgang Rindler

American Journal of Physics -- June 2009 -- Volume 77, Issue 6, pp. 498 | Cited 1 time

Online Publication Date: May 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This article is an expanded version of a talk given at the International Symposium Celebrating the 100th Birthday of Kurt Gödel (Vienna, 2006). It seeks to trace the path which led this preeminent mathematical logician to discover one of the famous results of General Relativity, the rotating Gödel Universe. This universe has some remarkable properties, which gave the philosophers plenty to worry about. It allows a person to travel into his own past, with all the ensuing causal paradoxes; it allows no unique temporal ordering of events; and though Gödel's Universe is rigid and infinite, the Foucault pendulum planes everywhere in it rotate in unison, a clear affront to adherents of Mach’s Principle. We also discuss some lesser known precursors in the field, who just missed discovering Gödel’s universe. While the article gives all the necessary derivations in simplified form (for example, of the metric and its geodesics), much of it should be accessible to the general reader, who can simply skip most of the mathematics. [Reprinted, with permission, from Kurt Gödel and the Foundations of Mathematics: Horizons of Truth, edited by Matthias Baaz, Christos H. Papadimitriou, Dana S. Scott, Hilary Putnam, and Charles L. Harper, Jr. (Cambridge U. P., New York, 2009).]
Show PACS
04.00.00 General relativity and gravitation

The two-body problem of ultra-cold atoms in a harmonic trap

Patrick Shea, Brandon P. van Zyl, and Rajat K. Bhaduri

American Journal of Physics -- June 2009 -- Volume 77, Issue 6, pp. 511 | Cited 5 times

Online Publication Date: May 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We consider two bosonic atoms interacting with a short-range potential and trapped in a spherically symmetric harmonic oscillator. The problem is exactly solvable and is relevant for the study of ultra-cold atoms. We show that the energy spectrum is universal, irrespective of the shape of the interaction potential, provided its range is much smaller than the oscillator length.
Show PACS
03.65.-w Quantum mechanics
30.00.00 ATOMIC AND MOLECULAR PHYSICS

Ohm’s law for a wire in contact with a thermal reservoir

M. J. Madsen

American Journal of Physics -- June 2009 -- Volume 77, Issue 6, pp. 516 | Cited 1 time

Online Publication Date: May 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Ohm’s law is one of the key empirical relations taught in introductory courses on electricity. Students often do a straightforward experiment to measure the current through a resistor as a function of voltage. These experiments typically yield a linear relation between the current and the voltage using carbon film resistors. However, the same measurements on long lengths of conducting wire (such as common wire resistivity kits) typically have a clear nonlinear component. The nonlinear behavior can be modeled using simple principles of heat transfer with a thermal reservoir. Experimental results are shown to agree well with this simple model.
Show PACS
01.50.Pa Laboratory experiments and apparatus
05.00.00 Statistical physics, thermodynamics, and nonlinear dynamical systems

Rotating structures and Bryan’s effect

Stephan V. Joubert, Michael Y. Shatalov, and Temple H. Fay

American Journal of Physics -- June 2009 -- Volume 77, Issue 6, pp. 520

Online Publication Date: May 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In 1890 Bryan observed that when a vibrating structure is rotated the vibrating pattern rotates at a rate proportional to the rate of rotation. During investigations of the effect in various solid and fluid-filled objects of various shapes, an interesting commonality was found in connection with the gyroscopic effects of the rotating object. The effect has also been discussed in connection with a rotating fluid-filled wineglass. A linear theory is developed, assuming that the rotation rate is constant and much smaller than the lowest eigenfrequency of the vibrating system. The associated physics and mathematics are easy enough for undergraduate students to understand.
Show PACS
47.00.00 Fluid dynamics
46.00.00 Continuum mechanics of solids

Lord Kelvin’s gyrostat and its analogs in physics, including the Lorenz model

Christopher Tong

American Journal of Physics -- June 2009 -- Volume 77, Issue 6, pp. 526 | Cited 2 times

Online Publication Date: May 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A gyrostat is a system of bodies whose relative motion does not alter the intrinsic mass distribution of the system. A solid gyrostat is an arbitrary rigid body attached to one or more axisymmetric rotors with their axes fixed in the carrier. A liquid gyrostat is a cavity in a rotating rigid body filled with an inviscid, homogeneous fluid. For certain conditions, gyrostats obey the Volterra equations of motion, a generalization of the Euler equations for a rigid body rotating about a fixed point. The Lorenz model is equivalent to a special case of a gyrostat in a forced, dissipative regime, as is its laboratory analog, the Malkus water wheel. Over a century ago, Lord Kelvin, the gyrostat’s inventor, attempted to formulate mechanical models of the elasticity of matter and the ether, using lattices of linked gyrostats. Opportunities for using gyrostats in the teaching of undergraduate mechanics, nonlinear dynamics, and fluid dynamics are discussed.
Show PACS
01.65.+g History of science
05.45.-a Nonlinear dynamics and chaos
47.00.00 Fluid dynamics

Initial phase and free-particle wave packet evolution

Theodore L. Beach

American Journal of Physics -- June 2009 -- Volume 77, Issue 6, pp. 538

Online Publication Date: May 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The evolution of the free-particle wave function in one dimension is the same as scalar Fresnel diffraction from a one-dimensional structure. Quantum mechanics courses often explore the propagation of Gaussian wave packets, but the diffractionlike mathematics is sufficiently tractable to investigate the propagation of other wave packets, both numerically and analytically. More importantly, the diffraction analogy facilitates the development of an intuitive understanding of the role that the initial phase plays in free-particle wave packet evolution. This article considers some of the effects of the initial phase function on the subsequent evolution of free-particle wave packets in the position representation. These considerations reinforce the idea that the classical mechanics limit embodied in the correspondence principle and formalized in the Ehrenfest theorem is necessarily an incomplete representation of quantum behavior.
Show PACS
03.65.-w Quantum mechanics
42.00.00 Optics

Gaussian wave packets in phase space: The Fermi gF function

Giuliano Benenti and Giuliano Strini

American Journal of Physics -- June 2009 -- Volume 77, Issue 6, pp. 546 | Cited 2 times

Online Publication Date: May 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A pure quantum state can be equivalently represented by means of its wave function ψ(q) or by the Fermi function gF(q,p), with q and p coordinates and conjugate momenta of the system of interest. We show that a Gaussian wave packet can be conveniently visualized in phase space by the curve gF(q,p)=0. The change in time of the gF=0 curve is calculated for a Gaussian packet evolving freely or under a constant or a harmonic force, and the spreading or shrinking of the packet is easily interpreted in phase space. We also discuss a gedanken prism microscope experiment for measuring the position-momentum correlation. This gedanken experiment, together with the well-known Heisenberg microscope and von Neumann velocimeter, is sufficient to fully determine the state of a Gaussian packet.
Show PACS
03.65.-w Quantum mechanics

Asymptotic approximations to Clebsch-Gordan coefficients from a tight-binding model

D. W. L. Sprung, W. van Dijk, J. Martorell, and D. B. Criger

American Journal of Physics -- June 2009 -- Volume 77, Issue 6, pp. 552

Online Publication Date: May 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The recurrence relations of the angular momentum vector addition coefficients are interpreted as a tight-binding model of a one-dimensional potential. From this model we derive their semi-classical limits in a simple manner, treating separately large J≈L+S and small J≈∣L−S∣. The resulting picture makes their qualitative behavior transparent to beginners, without the use of advanced concepts.
Show PACS
03.65.-w Quantum mechanics

Illustrating some implications of the conservation laws in relativistic mechanics

Timothy H. Boyer

American Journal of Physics -- June 2009 -- Volume 77, Issue 6, pp. 562 | Cited 3 times

Online Publication Date: May 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The conservation laws of nonrelativistic and relativistic systems are reviewed and some simple illustrations are provided for the restrictive nature of the relativistic conservation law involving the center of energy compared to the nonrelativistic conservation law for the center of mass. Extension of the nonrelativistic interaction of particles through a potential to a system that is Lorentz-invariant through order v2∕c2 is found to require new velocity- and acceleration-dependent forces that are suggestive of a field theory where the no-interaction theorem of Currie, Jordan, and Sudershan does not hold.
Show PACS
03.30.+p Special relativity

Optics in a field of gravity

Øyvind G. Grøn and Ø. Grøn

American Journal of Physics -- June 2009 -- Volume 77, Issue 6, pp. 570

Online Publication Date: May 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An observer at rest in a uniformly accelerated reference frame experiences a parallel gravitational field. As a result, rays of light are formed as circular arcs instead of being straight lines. We deduce how a sphere at rest in this frame and a freely falling sphere in this frame appear to an observer at rest.
Show PACS
04.00.00 General relativity and gravitation
back to top
RSS Feeds

The Atom and the Apple: Twelve Tales from Contemporary Physics

Sébastien Balibar and Roger Balian, Reviewer, Reviewer

American Journal of Physics -- June 2009 -- Volume 77, Issue 6, pp. 575

Online Publication Date: May 2009

Full Text: Read Online (HTML) | Download PDF

Abstract Unavailable
Show PACS
01.30.Vv Book reviews

BOOKS RECEIVED

American Journal of Physics -- June 2009 -- Volume 77, Issue 6, pp. 576

Online Publication Date: May 2009

Full Text: Read Online (HTML) | Download PDF

Abstract Unavailable
Close

Your Recent History Recent History Help

Recently Viewed

  1. Wick calculus using the technique of integration within an ordered product of operators
  2. Promoting instructional change via co-teaching
  3. The 1925 Born and Jordan paper “On quantum mechanics”
  4. A balsa violin
  5. Preparing physics graduate students to be educators

AAPT on:

close