The motion of spherical pendulum in z direction is described by nonlinear oscillation equation. 球面摆铅直方向的运动由一非线性振动方程描述。
An experimental study on the measurement of the aftereffect kinetic energy of spherical fragment penetrating steel armour by ballistic pendulum 用弹道摆测定球形破片侵彻钢质甲板后效动能实验研究