我们在研究物理问题中,常遇到一些突发现象。例如我们用不大的力推桌子,桌子静止不动,然后逐渐增大对桌子推力,当推力刚好超过最大静摩擦力时,桌子就由静止变为运动。可见推力达到某一限度时,桌子的运动状态发生突变。又如当升降机带着物体和体重计一起急剧下降时,体重计的读数小于物体的重量,当以重力加速度g加速下降时,体重计的读数便为零,即物体对支持物的压力等于零,产生完全失重状态。可见物体运动的加速度达到某一限度时,物体间的 We often encounter unexpected phenomena in the study of physical problems. For example, we use a small force to push the table, the table is stationary, and then gradually increase the thrust on the table, when the thrust just beyond the maximum static friction, the table will change from still to exercise. It can be seen that when the thrust reaches a certain limit, the movement of the table mutates. Another example is when the lift falls sharply with an object and a weight scale, the reading of the scale is less than the weight of the object. When the acceleration is decreased by the acceleration g, the reading of the scale is zero, that is, the pressure of the object on the support is equal to zero. Produce a completely weightless state. It can be seen that when the acceleration of the object reaches a certain limit,