单词 | Cycloid | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
释义 | CycloidThe cycloid is the locus of a point on the rim of a Circle of Radius rolling along a straightGalileo in 1599. Galileo attempted to find the Area byweighing pieces of metal cut into the shape of the cycloid. Torricelli, Fermat, andDescartes all found the Area. The cycloid was also studied by Roberval in 1634, Wren in 1658,Huygens in 1673, and Johann Bernoulli in 1696. Roberval and Wren found theMacTutor Archive). Gear teeth were also made out of cycloids, as first proposed by Desargues in the1630s (Cundy and Rollett 1989). In 1696, Johann Bernoulli challenged other mathematicians to find the curve which solves theLeibniz, Newton, Jakob Bernoulli and L'Hospital all solved Bernoulli's challenge.The cycloid also solves the Tautochrone Problem. Because of the frequency with which it provoked quarrels amongmathematicians in the 17th century, the cycloid became known as the ``Helen of Geometers'' (Boyer 1968, p. 389). The cycloid is the Catacaustic of a Circle for a Radiant Point on the circumference, as shown byJakob and Johann Bernoulli in 1692. The Caustic of the cycloid when the rays are parallel to the y-Axis is acycloid with twice as many arches. The Radial Curve of a Cycloid is a Circle. The Evoluteand Involute of a cycloid are identical cycloids. If the cycloid has a Cusp at the Origin, its equation in Cartesian Coordinates is
If the cycloid is upside-down with a cusp at , (2) and (3) become
(sign of flipped for ). The Derivatives of the parametric representation (2) and(3) are
The squares of the derivatives are
so the Arc Length of a single cycle is
Now let so . Then
The Arc Length, Curvature, and Tangential Angle are
The Area under a single cycle is
The Normal is
Bogomolny, A. ``Cycloids.'' http://www.cut-the-knot.com/pythagoras/cycloids.html. Boyer, C. B. A History of Mathematics. New York: Wiley, 1968. Cundy, H. and Rollett, A. Mathematical Models, 3rd ed. Stradbroke, England: Tarquin Pub., 1989. Gray, A. ``Cycloids.'' §3.1 in Modern Differential Geometry of Curves and Surfaces. Boca Raton, FL: CRC Press, pp. 37-39, 1993. Lawrence, J. D. A Catalog of Special Plane Curves. New York: Dover, pp. 192 and 197, 1972. Lee, X. ``Cycloid.''http://www.best.com/~xah/SpecialPlaneCurves_dir/Cycloid_dir/cycloid.html. Lockwood, E. H. ``The Cycloid.'' Ch. 9 in A Book of Curves. Cambridge, England: Cambridge University Press, pp. 80-89, 1967. MacTutor History of Mathematics Archive. ``Cycloid.''http://www-groups.dcs.st-and.ac.uk/~history/Curves/Cycloid.html. Muterspaugh, J.; Driver, T.; and Dick, J. E. ``The Cycloid and Tautochronism.'' http://php.indiana.edu/~jedick/project/intro.html. Pappas, T. ``The Cycloid--The Helen of Geometry.'' The Joy of Mathematics. San Carlos, CA: Wide World Publ./Tetra, pp. 6-8, 1989. Wagon, S. ``Rolling Circles.'' Ch. 2 in Mathematica in Action. New York: W. H. Freeman, pp. 39-66, 1991. Yates, R. C. ``Cycloid.'' A Handbook on Curves and Their Properties. Ann Arbor, MI: J. W. Edwards, pp. 65-70, 1952. |
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