Figuring the Acceleration of the Simple Pendulum

Autor/in	Lieberherr, Martin
Titel	Figuring the Acceleration of the Simple Pendulum
Quelle	In: Physics Teacher, 49 (2011) 9, S.576-577 (2 Seiten)Infoseite zur Zeitschrift PDF als Volltext Verfügbarkeit
Sprache	englisch
Dokumenttyp	gedruckt; online; Zeitschriftenaufsatz
ISSN	0031-921X
DOI	10.1119/1.3661108
Schlagwörter	Physics; Laboratory Equipment; Science Equipment; Motion; Kinetics; Geometric Concepts; Matrices; Measurement Techniques; Teaching Methods + Suchen Sie Ihr Suchwort? Physik; Laborausstattung; Bewegungsablauf; Kinetik; Elementare Geometrie; Matrizenrechnung; Messtechnik; Teaching method; Lehrmethode; Unterrichtsmethode
Abstract	The centripetal acceleration has been known since Huygens' (1659) and Newton's (1684) time. The physics to calculate the acceleration of a simple pendulum has been around for more than 300 years, and a fairly complete treatise has been given by C. Schwarz in this journal. But sentences like "the acceleration is always directed towards the equilibrium position" beside the picture of a swing on a circular arc can still be found in textbooks, as e.g. in Ref. 4. Vectors have been invented by Grassmann (1844) and are conveniently used to describe the acceleration in curved orbits, but acceleration is more often treated as a scalar with or without sign, as the words acceleration/deceleration suggest. The component tangential to the orbit is enough to deduce the period of the simple pendulum, but it is not enough to discuss the forces on the pendulum, as has been pointed out by Santos-Benito and A. Gras-Marti. A suitable way to address this problem is a nice figure with a catch for classroom discussions or homework. When I plotted the acceleration vectors of the simple pendulum in their proper positions, pictures as in Fig. 1 appeared on the screen. The endpoints of the acceleration vectors, if properly scaled, seemed to lie on a curve with a familiar shape: a cardioid. Is this true or just an illusion? (As Provided).
Anmerkungen	American Association of Physics Teachers. One Physics Ellipse, College Park, MD 20740. Tel: 301-209-3300; Fax: 301-209-0845; e-mail: pubs@aapt.org; Web site: http://scitation.aip.org/tpt
Erfasst von	ERIC (Education Resources Information Center), Washington, DC
Update	2017/4/10