抛物线

       将球放在滑道上制定的位置，然后扳动手柄，三个球会从不同的高度从滑道滚下，落入指定的网中。这些球在空中的运动轨迹是不同的抛物线。    

PARABOLA

       Place balls on designated positions on the slide track, and pull the lever. The three balls will roll down the slide track from different heights and fall into designated nets. The movement tracks of these balls in space are different parabolas.