英語聽力 學(xué)英語,練聽力,上聽力課堂! 注冊 登錄
> 在線聽力 > 英語高級聽力 > 英語時差 >  第1106篇

英語時差:水上漂

所屬教程:英語時差

瀏覽:

2022年01月11日

手機版
掃描二維碼方便學(xué)習(xí)和分享
https://online2.tingclass.net/lesson/shi0529/10000/10183/1106.mp3
https://image.tingclass.net/statics/js/2012

It's summertime, and you're on vacation. You sit beside a quiet pond, fishing, trying to relax, trying to think about nothing at all. You watch the leaves stirring, the water rippling in the sunshine, and the water bugs standing on the surface of the water.  How do they--Rats! Now your brain's working again, wondering how those bugs do that. Well relax, it's Moment of Science to the rescue. Today we'll explain Standing on Water.

There are two things involved in this trick: one is a property of the water, and the other has to do with the bug's feet. Let's start with the water.

Water molecules naturally stick to each other, due to a strong chemical attraction between the individual molecules. At the pond's surface, the uppermost water molecules experience this attraction as a strong pull toward each other, and downward from the water beneath them. This creates what's called "surface tension"--a somewhat compressed layer of water molecules right at the pond's surface. You can think of this layer as being like a tight film over the surface of the pond.

How does this help the water bug? If the surface water stuck to its feet as well as it stuck to the water below, the bug would be pulled under. As it turns out, the bug's feet are covered with waxy hairs that are "hydrophobic"--which means they chemically resist contact with water. This combination of strong surface tension and water-resistant feet is what lets our bug stand on the water, without even getting wet!

On our next program, we'll learn how water bugs move across this surface. Meanwhile, get back to your fishing!

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(biāo) 英語入門 發(fā)音 美語 四級 新東方 七年級 賴世雄 zero是什么意思遵義市港澳廣場英語學(xué)習(xí)交流群

網(wǎng)站推薦

英語翻譯英語應(yīng)急口語8000句聽歌學(xué)英語英語學(xué)習(xí)方法

  • 頻道推薦
  • |
  • 全站推薦
  • 推薦下載
  • 網(wǎng)站推薦