从一小筒油說起很早以前,当人們还使用吱吱吜吜响的木輪独輪車的时候,就在車上带着一小筒油作为润滑用。原来木轴上总不免有些小小的棱角,轴套里也有些坑坑洼洼,轴在轴套里轉动,坑洼不断地“咬住”棱角,使轉动受到了阻碍。这就是我们平常說的摩擦“阻力”,推車的人要费很多的力气来克服它。在轴上涂上一层油,这种阻力就减小,推起来就不那么费劲,油所起的这种作用就叫润滑。究竟为什么加了油就能减小阻力呢? 举一个例来說吧!一条木船搁在陆地上,要很多人才能推得动它;到了水里就很省力,一个人就能推 From a small barrel of oil, long ago, when people were still using squeaky wooden wheel unicycles, they took a small cylinder of oil for lubrication. The original wooden shaft can not help but some small corners, there are some pits in the sleeve, the shaft in the sleeve rotation, pits constantly “biting” corners, so that rotation has been hindered. This is what we usually call the “resistance” of friction. People in carts have to spend a lot of effort to overcome it. Applying a layer of oil on the shaft reduces this resistance and pushes it up less quickly. The effect of the oil is called lubrication. Why is it that the oil is used to reduce the resistance? For example, a wooden boat is put on land and many people need to push it; when it is in the water, it is very easy and one person can push it.