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高中《物理》下册第244页有这样一道习题:某人身高1.80米,至少用多高的镜子他才能看到自已全身?答案似乎很明显:0.90米。但我认为这只对了一半,即当镜子垂直于地面且镜子最高点处于头顶与眼中间高度时成立(见图一)。假如镜子倾斜放置时,情况会怎样? 镜子倾斜放置有两种摆法: 第一种:将图一中镜AB的位置绕其中点O旋转(见图二),但当B′点在OF连线上或右侧时,人体下部不可能成像。
The second volume of high school “Physics” on page 244 contains the following exercise: If a person is 1.80 meters tall, can he see his own body at least with a high-height mirror? The answer seems obvious: 0.90 meters. But I think this is only half true when the mirror is perpendicular to the ground and the highest point of the mirror is between the top of the head and the height of the eye (see Figure 1). If the mirror is placed at an angle, what happens? There are two pendulum methods for tilting the mirror: First: Rotate the position of the mirror AB in Figure 1 around its midpoint O (see Figure 2), but when the point B’ is in the OF When on the line or on the right, the lower part of the human body cannot be imaged.