时差N小时 锋利的刀刃有何特别之处?(上)（在线收听）

What’s So Special About A Sharp Knife?

锋利的刀刃有什么特别之处?

Everyone knows that a sharp knife cuts better than a dull one, but do you know why, exactly?

众所周知，锋利的刀刃比钝刀更加锋利，但你知道原理吗?

The purpose of the cutting edge of a knife is to concentrate the force that’s being applied at the handle.

刀刃的作用其实是将刀柄上的力集中起来。

When you push down on the handle of a knife you exert a force. The force on the handle and the edge are the same, but the areas in which the force is concentrated are quite different.

当你按下刀柄时，实际上你已经施加了一种力。刀把和刀刃上的力度其实都是等量的，但力的聚集区域不同，产生的效果也出现天壤之别。

At the handle your hand’s force is spread over a wide area, but on the cutting edge it is concentrated in a very small area, so therefore the pressure on the edge is much greater.

在刀柄处，力会分散在一个较广阔的区域，而在刀刃上，力会聚集在一个非常小的区域，因此刀刃上的压力会剧增。

You can easily see how this works with a piece of modeling clay, a nail with a wide head, and a nail with a small head.

只要借助一块橡皮泥、一枚宽头钉和一枚窄头钉，你很容易就能看到这一原理。