例题:一根有大小头的木头,(粗细变化均匀,密度均匀)在其重心处截成两部分后,究竟是哪部分重呢?对此问题,有两种观点:一种观点认为两部分等重,理由是当在重心处吊起若能平衡(静止在水平位置)就应该是等重的。另一种观点认为大头比小头重,而且持这种观点的人还很多, Example: What is the weight of a wood with a large head (with even thickness variation and uniform density) after it is cut into two parts at its center of gravity? There are two views on this issue: One view considers two parts. Equal weight, the reason is that if the balance can be lifted at the center of gravity (at rest in the horizontal position) it should be equal. Another view is that the big head is heavier than the small head, and there are still many people who hold this view.