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TED-Ed演讲:在外太空自在落体

宣布工夫:2018-04-15内容泉源:VOA英语学习网

Have you ever been floating in a swimming pool, all comfy and warm, thinking, "Man, it'd be cool to be an astronaut!

你能否已经浮在游泳池里,觉得十分满意,暖洋洋得,想着,“天啦,当一名宇航员太爽了!

You could float out in outer space, look down at the Earth and everything. It'd be so neat!"

你可以在外太空漂泊,俯瞰地球以及一切的统统。太棒了!“

Only that's not how it is at all.

但现实并不云云。

If you are in outer space, you are orbiting the Earth: it's called free fall.

假如你在外太空,你将会绕地球转动,这叫做自在落体。

You're actually falling towards the Earth.

现实上,你正朝着地球着落。

Think about this for a moment: that's the feeling you get if you're going over the top of a roller coaster, going, like, "Whoa!"

想一下这种觉得:你坐上云霄飞车,行将爬过顶端时会有 “喔哦!”的齰舌声。

Only you're doing this the whole time you're orbiting the Earth, for two, three, four hours, days. Whatever it takes, right?

只是这回,你将不断如许围绕着地球转,两个小时、三个小时、四个小时或好几天。无论多久都行,是吧?

So, how does orbiting work?

那么,怎样旋转的呢?

Let's take a page from Isaac Newton.

让我们讨教一下牛顿吧。

He had this idea, a little mental experiment: You take a cannon, you put it on top of a hill.

他有如许一个想法,也是一个小的心思实行:你拿来一个大炮,把它摆在山顶上。

If you shoot the cannonball, it goes a little bit away.

假如你发射炮弹,它会射到不远处。

But if you shoot it harder, it goes far enough so that it lands a little bit past the curvature of Earth.

但是假如你更猛地发射,它将“嗖”的飞到充足远,以致于它下降在地球外表的曲度以外。

Well, you can imagine if you shot it really, really, hard, it would go all the way around the Earth and come back— boom! — and hit you in the backside or something.

那么,想象一下,假使你十分十分猛地发射,它大概会绕着地球飞行很远,然后绕返来,砰一声,撞到你背面或什么工具。

Let's zoom way back and put you in a little satellite over the North Pole of the Earth and consider north to be up.

让我们把核心拉回太空,并把你放在一个位于地球北极上方的小卫星里,假定北极偏向为正向上。

You're going to fall down and hit the Earth.

你将会着落并撞向地球。

But you are actually moving sideways really fast.

但是,你实践正在十分疾速地向一旁挪动。

So when you fall down, you're going to miss.

以是,当你着落的时分,你将错过正下方。

You're going to end up on the side of the Earth, falling down, and now the Earth is pulling you back in sideways.

你将终极移到地球的一边,你往着落的同时地球把你往一旁拉。

So it's pulling you back in and you fall down, and so you miss the Earth again, and now you're under the Earth.

也便是说,你在降落时被地球往回拉,以是,你将再次错过地球。这时,你曾经挪动到地球的上面了。

The Earth is going to pull you up, but you're moving sideways still.

地球往上拉你,但是你依旧往一旁挪动。

So you're going to miss the Earth again.

以是,你不得不再次错过地球。

Now you're on the other side of the Earth, moving upward, and the Earth's pulling you sideways.

如今,你曾经挪动到地球的另一边,正往上挪动,而且地球正把你拉向一边(垂直朝向地球)。

So you're going to fall sideways, but you're going to be moving up and so you'll miss.

也便是说,你在往一边着落,但是,你正在疾速地向上挪动,以是你再次错过地球。

Now you're back on top of the Earth again, over the North Pole, going sideways and falling down, and yep -- you guessed it.

如今,你再次回到了地球顶端,北极上方,往一旁挪动,同时向着落,是的,你曾经猜到了。

You'll keep missing because you're moving so fast.

你将不断错过(地球),由于你正在飞速挪动。

In this way, astronauts orbit the Earth.

正是云云,宇航员围绕地球飞行。

They're always falling towards the Earth, but they're always missing, and therefore, they're falling all the time.

固然他们不断朝地球着落,但他们却不断错过(落回地球),因而,他们不断在着落。

They feel like they're falling, so you just have to get over it.

他们也觉得本人在着落,你根本上只能承受如许一种觉得。

So technically, if you ran fast enough and tripped, you could miss the Earth.

以是,技能上说,假如你跑得充足快,忽然绊一脚,你将离开地球。

But there's a big problem.

但是,这里有个大题目。

First, you have to be going eight kilometers a second.

第一,你必需每秒跑8公里。

That's 18,000 miles an hour, just over Mach 23!

也便是每小时1万8000英里,超越23马赫(23倍音速)!

The second problem: If you're going that fast, yes, you would orbit the Earth and come back where you came from, but there's a lot of air in the way, much less people and things.

第二个题目:假定你能挪动那么快,你将绕地球活动而且回到你的终点,但是一起上会有少量的氛围,固然,人和其他事物少少。

So you would burn up due to atmospheric friction.

以是,大气摩擦将招致你熄灭至尽。

So, I do not recommend this.

因而,我并不引荐如许做。

来自:千亿国际文娱网页版_千亿国际文娱|www.qy449.com 文章地点: http://www.tingvoa.com/html/20180415/550476.html