上面的情形是我们在生活中经常遇到的:用较小的力推地面上的箱子,箱子不动,再用较大的力推,箱子仍然不动,继续使用更大的力推,箱子终于被推动了,而人却趴在了地上……人趴在地上,当然是由于惯性的作用。当箱子运动以后,人的手(上身)与箱子一起向前运动,而人的脚由于惯性要保持原来的运动状态,继续静止,因此,上身会前倾,甚至摔倒。今天我们要研究的是另一个问题:摩擦力的大 The above situation is often encountered in our daily life: with a small force pushing the box on the ground, the box does not move, and then push with a larger force, the box still does not move, continue to use a greater push, the box Was finally pushed, while people are lying on the ground ... people lying on the ground, of course, is due to the role of inertia. When the box is moved, the human hand (upper body) moves forward with the box, while the human foot maintains its original state of motion due to inertia and continues to stand still. As a result, the upper body leans forward and even falls. Today we want to study is another question: friction big