For example, no matter how much a dancer wishes to leap off the floor and then start turning, the law of conservation of angular momentum absolutely prevents such a movement.

例如，无论一个舞者多么想要跳离地板，然后开始旋转，角动量守恒定律绝对阻止这样的动作。

youdao

You see it on the general exams for physics, and it's simply a matter of conservation of mechanical energy.

你会在一般的，物理考试中见到，这只是一个，机械能的问题。

youdao

Conservation of matter and energy in the universe.

宇宙的物质和能量守恒。

youdao