为什么会有摩擦力要推动地板上一个笨重的箱子,得费很大的力气。因为,地板和箱子之间的摩擦力阻碍它们之间的相互移动。物体越重,接触面越粗糙,摩擦力就越大。摩擦力是怎么产生的呢?用放大镜仔细观察一下,你会发现那些看上去光滑的物体表面,其实是凹凸不平的。当物体互相接触时 Why there is friction To promote a heavy box on the floor, a lot of effort. Because the friction between the floor and the box hinders their mutual movement. Objects heavier, tougher contact surface, the greater the friction. Friction is how to produce it? With a closer look at the magnifying glass, you will find those who look smooth surface of the object, in fact, is uneven. When objects touch each other