动量守恒

       当第一个小球被提起后松手放下，与其它球碰撞。这时，动球会突然停止运动，而最远端原来静止的小球会以动球相同的速度运动起来，这说明了动量的传递和守恒。

       小球被提起后，势能加大，放手后势能逐步转化为动能，在碰撞另一球时，后者发生运动，当运动到一定高度时“停摆”，表明动能逐步转化为势能，这说明了能量的转换和守恒。
    

Momentum Conservation

       When a small ball is lifted and then released to collide with another one. At the juncture of collision, the moving ball suddenly stops whereas the still ball at the far end will move at a velocity the same with the velocity of moving ball. This indicates transfer and conservation of momentum.

       After the small ball is lifted, its potential energy increases, after it is released, its potential energy has gradually converted to kinetic energy, when it hits another ball, the latter moves and when it reaches a certain height, it stops oscillating, showing kinetic energy has gradually converted to potential energy. This indicates conversion and conservation of energy.