Oscillation Chracteristics and Computer Measurement of a Pendulum Whose String Touches an Ellipse (Ⅱ) : Vertical Radius is Longer than Horizontal Radius

左右に振動する単振子の糸の上部が, 縮閉線である楕円に接する振子を試作し, コンピュータ測定を実施した。楕円の水平方向半径を25cmに設定し, それに比較して,鉛直方向半径を, 1.2倍の30cm, 1.4倍の35cm, 1.6倍の40cmの3種を選んだ。四半楕円をXYプロッタで描き, 厚さ10cmの発泡スチロール板を電熱線で切り, 左右対称の装置を作製した。装置の上部で, 2個の四半楕円が突き合わされ, その位置で糸の上端を固定し, 下端に錘を吊すと, 重力の作用のもと, 錘は楕円の伸開線に沿って振動する。糸の長さは, 水平半径を基準にして, 1倍の25cm, 1.5倍の37.5cm, 2倍の50cm, 3倍の75cmの4種である。縮閉線に糸が接して振動するとき, 錘が, 間隔4cmの2本の水平光線を切る一連の時刻を, 1/500秒の精度でコンピュータ計測した。振幅に対する周期変化率の数表を提供している。A trial equipment was made similar a cycloid pendulum devised by Christiaan Hyugens. Three ellipses of horizontal radius 25 cm and vertical radii 30, 35 and 40 cm were chosen as the evolute curves and each quarter ellipse was drawn by using a XY plotter. After cutting the foamed styrol plates 10 cm thickness with heating wire, the symmetrical evolute the foamed styrol plates 10 cm thickness with heating wire, the symmetrical evolute planes were mounted on the equipment. When a simple pendulum oscillates right and left, the string of the pendulum touched the evolute planes. The string lengths were 25, 37.5, 50 and 75 cm. The weight of the pendulum chopped two rays apart four centimeters in a horizontal plane and the periods to amplitude were measured by a computer with the accuracy of 1/500 second. The experimental characteristics of period with increasing amplitude are compared to the results of simulation. The variation rates of period corresponding to each amplitude are offered as a table with the parameters of the string length