What goes around and then stands still, and when it stands still, it falls?

This tricky puzzle stumped even the smartest people.

The riddle seems absurd, but it's perfectly logical once you find the correct answer. The challenge is to find the answer to the question: "What walks and then stands still, and then falls over?"

What do you think it is?

Leave your answer in the comments and see how many answers match.

Giang Pham

Source: https://vtcnews.vn/cai-gi-di-thi-dung-dung-thi-nga-ar971494.html