bounce-- the basketball, the super bouncy ball, and the golf

籃球、彈力球和高爾夫球──會彈得多高。

ball.

籃球、彈力球和高爾夫球──會彈得多高。

Now, I'm going to try the golf ball on top

現在我要從上到下把高爾夫球、

of the bouncy ball on top of the basketball,

彈力球和籃球疊在一起，

and then I'm going to explain how

再來我會解釋這個現象與超新星有什麼關聯。

it's related to a supernova.

再來我會解釋這個現象與超新星有什麼關聯。

Did you see that?

00:00:19,950 --> 00:00:20,950 你有看到嗎？

Probably not, so here it is again.

可能沒有，所以讓我們再看一次。

The golf ball bounced to 28 feet.

高爾夫球彈了28英尺高。

We dropped it from about 3 and 1/2 feet, so it went up 800%

我們讓它從大約3.5英尺高的位置落下， 所以它彈到了原本高度的800%。

of its dropped height.

我們讓它從大約3.5英尺高的位置落下， 所以它彈到了原本高度的800%。

In fact, if you consider that by itself-- the golf ball bounces

事實上，如果你只考慮單顆高爾夫球的話，

about 70% of it's dropped height--

它只會彈到約原本高度的70%──

it went as high as if it had fallen from 40 feet up.

它彈的高度就像是從它自己40英尺高的地方落下一樣。

That is awesome.

很神奇的一件事。

So how can we get the golf ball to bounce up

所以我們怎麼得到讓這高爾夫彈這麼高的能量的？

with that much energy?

所以我們怎麼得到讓這高爾夫彈這麼高的能量的？

Let's simplify it to these two balls.

讓我們把這問題簡化成兩個球。

When you drop them individually, each ball

當你讓他們個別掉落時，每顆球

starts out with some potential energy

一開始都有起始高度的位能。

from the height of the drop.

一開始都有起始高度的位能。

As the balls hit the ground, some energy

當球碰到地上時，球的一部分的能量

goes into heating up the ground, and some

會使得地板溫度上升，而一部分

goes into heating the ball.

會使球的溫度上升。

Because that energy left the ball system,

因為這些能量從球系統跑掉了，

you can't get back up to the same height.

球無法回到原本的高度。

But when you combine them, the tennis ball

但是當你把它們疊在一起時，這顆網球

goes higher than its dropped height, way higher.

會彈得遠比原本的高度還高。

Where does it get the extra energy?

它是從哪裡得到額外的能量的？

As the basketball bounces, it compresses, storing

當籃球要反彈時，它會先壓縮，

elastic potential energy.

並儲存彈力位能。

As it releases, it springboards the tennis ball upward

而當籃球從壓縮狀態釋放時，它使網球向上移動，

just at the right moment.

就在那時機。

This is like the double bounce on a trampoline

這就像兩個人在彈跳床上跳，

when you jump right before someone else.

當你在另一個人跳之前跳，

You prepare the elastic of the trampoline

你透過延展床面、儲存能量而提供了彈跳床面的彈力，

by stretching it and storing energy, which can then

你透過延展床面、儲存能量而提供了彈跳床面的彈力，

bounce the jumper even higher.

這使得之後跳的人可以彈得更高。

In the same way, the basketball stores energy

籃球也用同樣的方式透過壓縮儲存能量

in its compression and is able to push the tennis ball,

並藉此推動網球，

but just like the double bounce preparer,

但就像雙重彈跳中的準備者一樣，

the basketball can't go as high.

籃球無法彈高。

You can see that here.

你在這裡可以看到

It bounces even less when three balls are dropped together.

當三顆球一起落下時，它甚至會彈得更低。

Also during that transfer of energy,

此外，在能量轉移的過程中，

some momentum transfers from the basketball to the tennis ball,

一部分的動量會從籃球轉移到網球上，

and since the basketball starts with way

而且由於籃球的質量比較大， 它會帶比較多動量，網球的

more momentum because of its larger mass, the tennis ball's

而且由於籃球的質量比較大， 它會帶比較多動量，網球的

velocity increases by a lot.

速度會增加許多。

And it flies up, up, and away.

於是它就飛得又高又遠。

Now, back to the triple super ball bounce.

讓我們回來看三顆球的超級彈跳。

Now, do you get the energy from the basketball's bounce being

現在你從籃球的彈跳中得到能量，

transferred into the bounce of the super bouncy

傳遞給彈力球使其彈跳，

ball, which is then transferred to the golf ball's bounce.

爾後又傳遞至高爾夫球供其彈跳。

You put the same amount of energy or momentum

你把同樣的能量或動量

from two more massive objects into a smaller object,

從兩個質量更大的物體送到小物體，

and it will go much faster, epic,

它就飛得更快、超級快，

just like the explosions of a supernova, which

就像超新星爆炸一般，

may seem unrelated.

這兩者看似沒什麼關聯。

But what we just did is analogous to the process

但我們剛剛演示的正是超新星爆炸所發生現象的類比。

that occurs during the explosion of a supernova.

但我們剛剛演示的正是超新星爆炸所發生現象的類比。

Just like our more massive basketball transfers momentum

就像我們質量較大的籃球傳遞動量

to the smaller balls, energy from the dense core

給其他質量比較小的球，能量會從密度大的超新星核心

of the supernova is transferred in a shockwave that

藉由震波傳送

moves through the star to the less dense layers

穿越星體到達密度較小的殼層

and accelerates them outward at a super high velocity.

並加速它們，驅使其以極快的速度向外。

More massive or denser layers in the core of the supernova

超新星的核心中質量或密度較大的殼層

begin to collapse when fusion stops there.

當裡頭的核融合反應停止時，便會開始塌縮。

The collapse is halted when the neutrons in the core

簡單來說，塌縮到接近核心的中子時才會停止。

actually touch, sort of.

(原翻譯者補充:直到中子的簡併壓力足以抵抗重力，塌縮才會停止。)

This causes the implosion to rebound and bounce outward.

這引發了內爆，使得外部的殼層再向外反彈。

You end up with a dense core left behind

你最後會剩下一顆密度極大的核心

and these wild outer shells of star exploding outward, pretty

以及爆發四散的外部殼層，

cool.

超酷。

And, of course, if you try this at home, which you should,

當然，如果你在家裡試的時候，

you have to make sure the balls are perfectly vertically

你必須讓這些球完美地鉛直置中，

aligned because any off centeredness gets amplified

因為就算只有一點偏離中心位置，

by the two points of contact, which

這偏移都會被這兩個接觸點放大。

is why we sadly couldn't get the quadruple tower of balls

這就是為什麼我們很遺憾沒辦法讓四顆球的例子

to work.

成功。

But if you put a little ring of hot glue or something

但在球上塗一小圈熱熔膠或是

similar on the balls, it helps to balance them.

類似的東西在球上的話，可以幫助它們平衡。

Happy physicsing.

Happy physicsing.

[MUSIC PLAYING]

00:03:15,120 --> 00:03:33,553