时差N小时 锋利的刀刃有何特别之处?(上)

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 applied¹ 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 exert² 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。

1 applied   

adj.应用的；v.应用，适用

参考例句：

• She plans to take a course in applied linguistics.她打算学习应用语言学课程。
• This cream is best applied to the face at night.这种乳霜最好晚上擦脸用。

2 exert   

vt.用（力），尽（力），运用，发挥，施加

参考例句：

• He likes to exert his authority.他喜欢行使自己的权力。
• We must exert ourselves to catch up with them,or it would be too late.我们要急起直追，否则就太晚了。