free pendulum

例句：

1. 1. The free pendulum swings back and forth in the wind.
   风中，自由摆锤来回摆动。
2. 2.The free pendulum is a popular tool for measuring the Earth's rotation.
   自由摆锤是一种测量地球自转的流行工具。
3. 3. The free pendulum was used to measure the accuracy of the clock.
   自由摆锤用于测量钟表的准确性。