英语 英语 日语 日语 韩语 韩语 法语 法语 德语 德语 西班牙语 西班牙语 意大利语 意大利语 阿拉伯语 阿拉伯语 葡萄牙语 葡萄牙语 越南语 越南语 俄语 俄语 芬兰语 芬兰语 泰语 泰语 泰语 丹麦语 泰语 对外汉语

听力文摘:利刃特别在何处?

时间:2020-08-20 09:16来源:互联网 提供网友:nan   字体: [ ]
特别声明:本栏目内容均从网络收集或者网友提供,供仅参考试用,我们无法保证内容完整和正确。如果资料损害了您的权益,请与站长联系,我们将及时删除并致以歉意。
    (单词翻译:双击或拖选)

What’s So Special About A Sharp Knife?

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

The purpose of the cutting edge of a knife is to concentrate the force that’s being applied1 at the handle.

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.

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.

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. First hold the nail with the wide head by its shaft2 and push it head-first into the ball of clay. Then do the same with the small-headed nail.

The small-headed nail goes into the clay much more easily than the wide-headed nail. Since the head of the small nail has less surface area than the big one, the force of your push is concentrated in a smaller area, exerts more pressure on the clay, and so the nail goes in more easily. The same principal causes pointed3 high-heeled shoes to sink into a soft surface more easily than flat shoes.

By applying this principal to the knife you can see that with a keener edge there’s a greater concentration of the pressure on the edge, so it takes much less force to make the knife cut.


点击收听单词发音收听单词发音  

1 applied Tz2zXA     
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 shaft YEtzp     
n.(工具的)柄,杆状物
参考例句:
  • He was wounded by a shaft.他被箭击中受伤。
  • This is the shaft of a steam engine.这是一个蒸汽机主轴。
3 pointed Il8zB4     
adj.尖的,直截了当的
参考例句:
  • He gave me a very sharp pointed pencil.他给我一支削得非常尖的铅笔。
  • She wished to show Mrs.John Dashwood by this pointed invitation to her brother.她想通过对达茨伍德夫人提出直截了当的邀请向她的哥哥表示出来。
本文本内容来源于互联网抓取和网友提交,仅供参考,部分栏目没有内容,如果您有更合适的内容,欢迎点击提交分享给大家。
------分隔线----------------------------
TAG标签:   听力文摘
顶一下
(0)
0%
踩一下
(0)
0%
最新评论 查看所有评论
发表评论 查看所有评论
请自觉遵守互联网相关的政策法规,严禁发布色情、暴力、反动的言论。
评价:
表情:
验证码:
听力搜索
推荐频道
论坛新贴