To clarify the process underpinning the apparently counterintuitive phenomena observed in the freefall experiments conducted by Hamm and Géminard [Am. J. Phys. 78, 828 (2010)], a simple dynamical model of a vertically falling train of one-dimensional rigid segments impinging onto an inelastic horizontal plate in three-dimensional space was developed. The nonlinear governing equations were numerically integrated, and it was observed that the train of rigid segments falls virtually faster than a particle in freefall under gravity. We found that the maximum bend angle between successive chain links largely affects on the acceleration. The presented model reproduced the coiling spontaneously occurring in the pile, which is considered as a key mechanism and is shown to be a consequence of the three-dimensional spiral structure that arises due to dissipative locking of segments in mid-air. As one of the mechanical aspects underpinning the apparently counterintuitive phenomena, the downward tensile force exerted by the pile was focused on.

中文翻译：

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刚性节段自由落体列车的简单动力学模型

为了弄清由Hamm和Géminard[Am。J.物理 78，828（2010）]，开发了一个简单的动力学模型，该模型是一维刚性段垂直下落的列车撞击三维空间中无弹性水平板上的情况。非线性控制方程被数值积分，并且观察到，在重力作用下，刚性链段的下降实际上比自由落体的粒子下降快。我们发现，连续链节之间的最大弯曲角度对加速度有很大影响。提出的模型再现了自发发生在桩中的盘绕，这被认为是关键机制，并且显示出是由于段的耗散锁定在空中而产生的三维螺旋结构的结果。作为支撑明显违反直觉的现象的机械方面之一，