Why does the Greenland Paddle work?

为什麽使用格陵兰桨是可行的？

youdao

So, it's a trivial matter, by looking at what is the weight and how far does it drop, to say OK, how much work is done by the paddle wheel.

好，让我们看看重物的质量,以及它下落的距离，就知道桨轮做了多少功。

麻省理工公开课 - 热力学与动力学课程节选

One elderly woman recalled getting hit in the face with a matkot paddle and needing dental work.

WSJ: In Israel, Sounds of Spring Include Thwack of Paddleballs