I used first the conservation - of mechanical energy — there was no friction — and then I showed you that it's completely consistent with the work-energy theorem, so what would you do now?

首先，我用了机械能，守恒定律-，这里没有摩擦力-，我会向你们展示，这，和功能定理完全一致，现在你会怎么做呢？

youdao

And so you could have used the work-energy theorem or you can use the conservation of mechanical energy.

所以你也可以用，功能定理，或者是机械能，守恒定律。

youdao

His sign is occasionally removed by officials for conservation work and a replica is used as a substitute - the replica is now being used again to replace the stolen original.

BBC: Auschwitz's sign of death and defiance