摘要:

The use of a roller coaster for external classroom studies of kinematics, forces, dynamics, and energy conservation is discussed. Experimental accelerometer measurements of the vertical forces acting on riders of the Blue Streak at Cedar Point in Sandusky, Ohio are presented. Theoretically, the track profile is used to calculate/predict the vertical forces acting on a rider at the hilltops, valley bottoms, and several other points of interest along the track. Finally the experimental results and theoretical predictions are compared in the context of a rider’s experiences.

ISSN:0002-9505    

DOI:10.1119/1.16813

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

The uptake of fluid in porous material is observed in an experiment which is simple to perform and which yields results of precision better than 1%. In agreement with theory appropriate to a horizontal blotter, the square of the distance traveled by the liquid is proportional to the time. For glycerol solutions the slope of this curve is shown to be proportional to the inverse of the square root of their viscosities.

ISSN:0002-9505    

DOI:10.1119/1.16814

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

An undergraduate computational project is described. A set of rate equations for a four‐level laser is presented. The steady‐state equations are solved exactly to find nonlasing and lasing solutions and the critical pump rate for the transition between them. The steady‐state solutions are used as a guide to the introduction of suitable dimensionless variables for the rate equations. Illustrative numerical solutions of the rate equations in dimensionless form are presented. The detailed account given of this example is used to bring out a number of points about teaching computational physics.

ISSN:0002-9505    

DOI:10.1119/1.16815

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

Holographic interferometry was used to visualize a low‐velocity cooled air flow. The physical properties of the heat exchange of the system were investigated using holographic interferometry.

ISSN:0002-9505    

DOI:10.1119/1.16816

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

Electrostatic precipitation within a 20.4‐lcontainer onto a solid‐state charged‐particle detector is employed to simultaneously collect and detect radon‐decay daughter ions. Essentially complete isolation of the 6003‐keV α particles associated with21884Po decay, for which the half‐life is 3.05 min, allows radon concentrations in clean, dry air of 4 pCi/lto be determined in 15 min of operation with ∼11% statistical uncertainty. A detailed description of this simple system is given, and its absolute detection efficiency is measured as a function of precipitation voltage and relative humidity.

ISSN:0002-9505    

DOI:10.1119/1.16817

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

The performance of real heat engines can be characterized by their power versus efficiency curves. Real heat engines with sources of irreversibility that include friction and heat leaks exhibit fundamentally different power versus efficiency curves than those predicted by many previous studies in the finite‐time thermodynamics of endoreversible heat engines, in which finite‐rate heat transfer was the only irreversibility considered. It is shown that the thermoelectric generator provides an instructive illustration of a cyclic, irreversible heat engine with a power versus efficiency curve that qualitatively reproduces the key features of the corresponding curves for real heat engines. The generic sources of irreversibility are easily identifiable and analytically expressed so as to reveal more transparently the basis for the power versus efficiency characteristic.

ISSN:0002-9505    

DOI:10.1119/1.16818

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

This paper provides general mean field calculations of the entropy for an ensemble ofNmagnetic moments with an arbitrary spin value. Expressions for the case with an external magnetic field have been known for many years and have usually been calculated using the canonical ensemble partition function. Less well‐known calculations in the microcanonical ensemble are also demonstrated in this paper; they involve the method of Lagrange multipliers. In addition, various special cases and relevant approximations are discussed.

ISSN:0002-9505    

DOI:10.1119/1.16819

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

The time dependence of the wave packet spreading is investigated for the case of a particle confined in a one−dimensional box. (AIP)

ISSN:0002-9505    

DOI:10.1119/1.16820

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.16821

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.16822

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP