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SSS 2010-03-30

时间:2010-05-20 06:26来源:互联网 提供网友:mark@li   字体: [ ]
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    (单词翻译:双击或拖选)

This is Scientific American's 60-Seconds Science. I'm Karen Hopkin. This will just take a minute.

 

Elephants. They’re the SUVs of the animal kingdom. They’re big and rugged1, and can carry lots of cargo2. And now a study in the Proceedings3 of the National Academy of Sciences suggests they come equipped with the quadruped version of all-wheel drive.

When it comes to locomotion4, elephants are not exactly fleet of foot. And they seem to hold their legs straighter than other animals do, at least when they walk. So scientists set out to examine more closely how elephant limbs mechanically move all that mass around.

Six Asian elephants walked or ran over a sidewalk equipped with pressure sensors5, as the scientists used high-speed video cameras to monitor their gait. And they found that elephant legs actually do bend enough to provide significant leverage6 when on the move. More surprising is that pachyderms’ front and rear legs are on equal footing when it comes to acceleration7 and braking. All other four-legged animals, like dogs or cats or horses, divvy up those duties. With their rear legs powering the push forward, and their front legs acting8 as brakes.

That arrangement lets elephants trade speed for stability. Sadly, it does nothing for their fuel economy. Of course, they do have the roomiest trunk.

 

Thanks for the minute for Scientific American's 60-Seconds Science. I'm Karen Hopkin.
 


点击收听单词发音收听单词发音  

1 rugged yXVxX     
adj.高低不平的,粗糙的,粗壮的,强健的
参考例句:
  • Football players must be rugged.足球运动员必须健壮。
  • The Rocky Mountains have rugged mountains and roads.落基山脉有崇山峻岭和崎岖不平的道路。
2 cargo 6TcyG     
n.(一只船或一架飞机运载的)货物
参考例句:
  • The ship has a cargo of about 200 ton.这条船大约有200吨的货物。
  • A lot of people discharged the cargo from a ship.许多人从船上卸下货物。
3 proceedings Wk2zvX     
n.进程,过程,议程;诉讼(程序);公报
参考例句:
  • He was released on bail pending committal proceedings. 他交保获释正在候审。
  • to initiate legal proceedings against sb 对某人提起诉讼
4 locomotion 48vzm     
n.运动,移动
参考例句:
  • By land,air or sea,birds are masters of locomotion.无论是通过陆地,飞越空中还是穿过海洋,鸟应算是运动能手了。
  • Food sources also elicit oriented locomotion and recognition behavior patterns in most insects.食物源也引诱大多数昆虫定向迁移和识别行为。
5 sensors 029aee483db9ae244d7a5cb353e74602     
n.传感器,灵敏元件( sensor的名词复数 )
参考例句:
  • There were more than 2000 sensors here. 这里装有两千多个灵敏元件。 来自《简明英汉词典》
  • Significant changes have been noted where sensors were exposed to trichloride. 当传感器暴露在三氯化物中时,有很大变化。 来自辞典例句
6 leverage 03gyC     
n.力量,影响;杠杆作用,杠杆的力量
参考例句:
  • We'll have to use leverage to move this huge rock.我们不得不借助杠杆之力来移动这块巨石。
  • He failed in the project because he could gain no leverage. 因为他没有影响力,他的计划失败了。
7 acceleration ff8ya     
n.加速,加速度
参考例句:
  • All spacemen must be able to bear acceleration.所有太空人都应能承受加速度。
  • He has also called for an acceleration of political reforms.他同时呼吁加快政治改革的步伐。
8 acting czRzoc     
n.演戏,行为,假装;adj.代理的,临时的,演出用的
参考例句:
  • Ignore her,she's just acting.别理她,她只是假装的。
  • During the seventies,her acting career was in eclipse.在七十年代,她的表演生涯黯然失色。
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