第21届全国中学生物理竞赛预赛第6题的原题:有一种高脚酒杯,图略.杯内底面为一凸起的球面,球心在顶点O下方玻璃中的C点.球面的半径R=1.5cm.O到杯口平面的距离为8.0cm,在杯脚底中心处P点紧贴一张画片,P点距O点6.3cm,这种酒杯未斟酒时,若在杯口处向杯底方向观看,将看不出画片上的 The 6th National Junior High School Physics Contest preliminary question No. 6 of the original title: there is a kind of high-pitched glass, the figure is slightly. The bottom of the cup is a convex spherical surface, the center of the sphere is at the point C in the glass below the vertex O. The radius of the spherical surface R =1.5cm.O to the cup plane distance is 8.0cm, in the center of the bottom of the cup P point close to a picture, P point from the O point 6.3cm, this wine glass is not drinking, if the cup at the mouth Looking at the direction of the bottom of the cup, you will not see the picture on the