2 sentences

1. 物理学家正在观察钟摆的摆动规律。

   wù​lǐ​xué​jiā zhèng​zài guān​chá zhōng​bǎi de bǎi​dòng guī​lǜ.

   Physicists are observing the laws of the pendulum's swing.

   Source: Dong Chinese Dictionary

2. 那个古老挂钟的钟摆正在箱体里来回摆动。

   nà gè gǔ​lǎo guà​zhōng de zhōng​bǎi zhèng​zài xiāng​tǐ lǐ lái​huí bǎi​dòng.

   The pendulum of that old wall clock is swinging back and forth inside the case.

   Source: Dong Chinese Dictionary