挂在墙壁上的石英钟,当电池的电能耗尽而停止走动时,其秒针往往停在刻度盘上“9”附近的位置处.为什么?秒针在转动过程中,其重心位置不变,且重力方向一直是竖直向下的.当秒针从“‘‘12”运动至∥6,,时,秒针向下走,重力不会阻碍秒针运动;当秒针从“6”运动至“】2”时,秒针向上 A quartz clock hung on the wall, when the battery’s power is exhausted and stops moving, its second hand often stops at the position near the dial “9”. Why? The second hand is in the same position and gravity when the second hand is rotating The direction is always vertical. When the second hand moves from “12” to ∥6, , the second hand goes down, gravity does not impede the movement of the second hand; when the second hand moves from “6” to “2” , second hand up