英語聽力 學英語,練聽力,上聽力課堂! 注冊 登錄
> 在線聽力 > 有聲讀物 > 英語雜志 > 英語聽力文摘 >  第719篇

英語聽力文摘706 地球的引力改變過么?

所屬教程:英語聽力文摘

瀏覽:

2018年07月19日

手機版
掃描二維碼方便學習和分享
https://online2.tingclass.net/lesson/shi0529/0007/7643/706.mp3
https://image.tingclass.net/statics/js/2012
Has Earth’s Gravitational Pull Been Changing?

Don, why are you slouching? Don’t you know it’s bad for you?

Did you know that about 200 tons of debris strike the Earth every day? So I was thinking! Although most of this stuff burns up in the atmosphere, the resulting dust still settles and adds to the Earth’s mass. That’s about half a million tons per year!

All right, but what does all this have to do with your posture?

Sit Up Straight

So if the earth keeps accumulating mass, doesn’t that mean that the Earth’s gravitational pull has been increasing? After all, gravity is directly proportional to mass.

Are you saying you can’t sit up straight because gravity is stronger now than it used to be?

Admit it, Yaël–it’s a good one.

Earth’s Mass

Earth’s mass in metric tons is approximately six followed by twenty-one zeroes. So assuming that your estimate is correct, and the Earth accumulates a half a million tons of debris every year, this means that in the sixty million years since dinosaurs existed the Earth would have accumulated approximately thirty trillion tons of meteoric debris. That’s thirteen zeroes.

The point is that a number with thirteen zeroes is minuscule relative to a number with twenty-four zeroes. While thirty trillion tons sounds impressive, it is nothing compared to the Earth’s total mass. So it’ s definitely not all that extra gravity that’s making you slouch

用戶搜索

瘋狂英語 英語語法 新概念英語 走遍美國 四級聽力 英語音標 英語入門 發(fā)音 美語 四級 新東方 七年級 賴世雄 zero是什么意思無錫市茶洲苑英語學習交流群

網站推薦

英語翻譯英語應急口語8000句聽歌學英語英語學習方法

  • 頻道推薦
  • |
  • 全站推薦
  • 推薦下載
  • 網站推薦