Oscillation Characteristics and Computer Measurement of a Pendulum Superimposed Gradually Hard Force and Gradually Soft Force

ばねを鉛直に緩く張り，ばねに対して直角に変位すると，変位に比例しない非線形復元力が得られ，振幅の増加と共に周期が減少する漸硬特性を示す。これに対して，物理振子は，振幅の増加と共に周期が増加する漸軟特性を示す。今回，漸硬復元力と漸軟復元力を，同時に加えた振子を作製して実験を行った。復元力の相違による振動特性を理解し，コンピュータ計算を基本とした物理実験教材の開発に一助となるであろう。運動方程式を数値的に解き，種々のコンピュータ・シミュレーションを行い，実験結果との比較を行った。When a spring is loosely stretched along a vertical line, the perpendicular displacement to the spring yields the nonlinear restoring force which is not proportional to the displacement. The force shows gradually hard characteristics whose period decreases with increasing amplitude. In opposition of this, a physical pendulum shows gradually soft characteristics whose period increases with increasing amplitude. A trial pendulum was made which applied simultaneously both fradually hard and gradually soft restoring force. The experiments are accomplished with a computer. We can comprehend the oscillation characteristics by the difference of restoring forces. It gives an example of the development of the experimental teaching material in physics based on computer measurement. The motions of the pendulum are also numerically analysed by means of computer simulaions and the expermental results are comared with the simulations