一、在固体压强中的应用例1 一正方体的边长为10 cm,从垂直表面方向打一深为10 cm,直径为2 cm的圆洞.将不同的表面放在桌子中央,它对水平桌面的压强和未打洞时相比较是如何变化的? 分析:依题意可知,此圆洞是在两个平行表面处垂直打通的,因此除了这两个表面在放置时受力面积要减小外,其余四个表面的受力面积均不变.由于打了一个圆洞,所以正方体对 I. Application in solid pressure Example 1 The side of a cube has a length of 10 cm and a deep hole with a depth of 10 cm and a diameter of 2 cm is drilled from the vertical surface. A different surface is placed at the center of the table and it is horizontal. How does the pressure on the desktop change when compared to when no hole is drilled? Analysis: According to the meaning of the problem, this hole is perpendicularly opened at two parallel surfaces, so the force area is reduced except when these two surfaces are placed. On the outside, the remaining four surfaces have the same force area. Because of the round hole, the cube