重心是物体所受重力的作用点．有些杠杆类、机械功、机械能类物理竞赛题的正确解答与物体重心的位置有着密切的关系,重心位置的确定成为解答这类竞赛题的突破口和切入点, 下面举几例加以说明．一、杠杆类竞赛题中的重心问题 The center of gravity is the point of gravity of the object. Some of the correct answers for physics contests of levers, mechanical work, and mechanical energy are closely related to the location of the object’s center of gravity. The determination of the center of gravity becomes a breakthrough point and point of entry for answering such competition questions. Here are some examples to illustrate. First, the focus of the problem of leverage competition