Less Is More
It sounds all wrongdrilling holes in a piece of wood to make it more resistant to knocks. But it works because the energy from the blow gets distributed throughout the wood rather than focusing on one weak spot. The discovery should lead to more effective and ligher packaging materials.
Carpenters have known _____1_____ centuries that some woods are tougher than others. Hickory, for example, was turned into axe handles and cartwheel spokes because it can absorb shocks without breaking. White oak, for example, is much more easily damaged, ____2____ it is almost as dense.1 Julian Vincent at Bathe University and his team were convinced the woods internal structure could explain the differences.
Many trees have tubular vessels that run _____3____ the trunk and carry water to the leaves. In oak they are large, and arranged in narrow bands, but in hickory they are smaller, and more evenly distributed. The researchers ____4____ this layout might distribute a blows energy throughout the wood, soaking up a bigger hit. To test the idea, they drilled holes 0.65 millimetres across into a block of spruce, a wood with ____5____vessels, and found that____6___ withstood a harder knock. ___7___ when there more than about 30 holes per square centimeter did the woods performance drop off.
A uniform substance doesnt cope well with knocks because only a small proportion of the material is actually _____8____. All the energy from the blow goes towards breaking the material in one or two places, but often the pieces left ____9___ are pristine.
But instead of the energy being concentrated in one place, the holes provide many weak spots that all absorb energy as they break, says Vincent. You are controlling the places _____10____ the wood breaks, and it can then absorb more ____11____, more safely.
The researchers believe the principle could be applied to any material____12____ example, to manufacture lighter and more protective packaging. It could ____13____ be used in car bumpers, crash barriers and armour for military vehicles, says Ulrike Wegst, ____14_____ the Max Plank Institute for Mental Research in Stuttgart. But she emphasizes that youd _____15_____ to to design the substance with the direction of force in mind. The direction of loading is crucial, she says.
1. A) for B) since C) in D) at
2. A) but B) although C) and D) despite
3. A) down B) over C) up D) into
4. A) discovered B) concluded C) found D) thought
5. A) no B) per C) each D) every
6. A) the idea B) it C) they D) the spruce
7. A) If B) Just C) Only D) Rarely
8. A) effected B) beaten C) slapped D) affected
9. A) behind B) beyond C) for D) intact
10. A) which B) where C) that D) there
11. A) water B) air C) energy D) safety
12. A) among B) in C) as D) for
13. A) also B) besides C) else D) yet
14. A) over B) at C) around D) on
15. A) necessity B) must C) need D) had
看报纸来提高你的雅思词汇量
雅思词汇记忆方法汇总
每日雅思词汇:租房词汇
雅思词汇:音乐词汇知多少
雅思词汇:好多鱼
雅思词汇分类备考
雅思每日词汇:如何表赞同
每日雅思词汇:"keep"的常用搭配
每日雅思词汇:有特殊含义的短语
雅思每日词汇:多吃蔬菜有益健康
每日雅思:让你生活渐好的10句箴言
教你如何做到对雅思词汇的过目不忘
每日雅思词汇:国外的商店
雅思词汇:搞定超市的“海鲜区”
当你出国签证时你一定会遇到的雅思词汇
雅思词汇:医院及医疗疾病科目
雅思考试常见词汇:anxious
雅思词汇的4大记忆方法
雅思词汇:英语中的汉语借词
每日雅思词汇:馋嘴甜点
雅思词汇:最潮词汇
每日雅思词汇:各种“衰退”的英语表达
每日雅思词汇:各种牛仔裤
每日雅思词汇:各种蔬菜
每日雅思词汇:常见天气的说法
每日雅思词汇:各种颜色
每日雅思词汇:自然灾害
雅思词汇之味道类
雅思词汇:常见的中式早餐
每日雅思词汇:各种自然灾害
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |