飞石系绳的力学分析

旋转绳索使拴在前端的沙包获得速度后甩出; 待其飞过前方高处的铁杆后, 收紧绳索使沙包 以铁杆为悬挂点作圆周运动; 当沙包接近最低点时快速抽拉绳索; 基于动量矩守恒定律, 沙 包的切向速度因旋转半径缩短而增加, 继而牵引绳索对铁杆缠绕. 摩擦力可以使绳索具有极 高的承载能力.

A note to the mechanical principle in knotting with fly-stone

A rope can be knotted on a distant pole by using a sandbag connected at its end. Spin the rope to enhance the sandbag’s velocity and throw it out; pull the rope tightly to induce the sandbag rotating downward when it flies over the pole; shorten the rotating radius of the sandbag when it closes to the lowest point with increased velocity from the gravity potential energy. The sandbag’s velocity increases with the radius shortening on the momentum equilibrium, and then the rope may mound on the pole. The friction between the rope and pole can provide a great magnitude of load capacity.