The men in Apollo 10 reached a record-breaking speed of around 25,000 miles per hour when the shuttle re-entered the Earth's atmosphere in 1969.

1969 年，阿波羅十號重返地球表面時，太空梭裡的人達到每小時約兩萬五千哩移動速度，破了紀錄。

Wouldn't we save a lot of time to be able to move that fast?

假如我們能移動得這麼快，不是省下了很多時間嗎？

But what's the catch?

但這有何問題呢？

Air is not empty.

空氣並非無雜質。

Elements like oxygen and nitrogen, even countless dust particles, make up the air around us.

像是氧、氮元素等元素，甚至是數不盡的塵埃微粒，組成了環繞四周的空氣。

When we move past these things in the air, we're rubbing against them and creating a lot of friction, which results in heat.

我們移動時，會和空氣中這三樣物質擦身而過，進而製造許多摩擦力，產生熱能。

Just like rubbing your hands together warms them up or rubbing two sticks together makes fire.

就像是摩擦雙手取暖，或者摩擦兩根棍子取火。

The faster objects rub together, the more heat is generated.

摩擦的速度越快，產生的熱能越多。

So, if we're running at 25,000 miles per hour, the heat from friction would burn our faces off.

所以，如果我們每小時跑到兩萬五千哩，摩擦力產生的熱能會把我們的臉燒掉。

Even if we somehow withstood the heat, the sand and dirt in the air would still scrape us up with millions of tiny cuts all happening at the same time.

即使人體能夠承受那個熱度，空氣中的沙粒及塵土，仍會同時以數百萬的微小切割刮傷我們的皮膚。

Ever seen the front bumper or grill of a truck?

看過卡車車頭或前保險桿嗎？

What do you think all the birds and bugs would do to your open eyes or exposed skin?

你覺得小鳥及蟲子撞上你那睜開的雙眼及曝露在外的皮膚會發生什麼事？

Okay, so you'll wear a mask to avoid destroying your face.

好吧！可以戴上防護面具來避免臉受傷。

But what about people in buildings between you and your destination?

但在你和目的地之間大樓裡的人們怎麼辦？

It takes us approximately one-fifth of a second to react to what we see.

看到東西之後，我們大約需要五分之一秒的時間去反應。

By the time we see what is ahead of us and react to it -

當我們看見事物並做出反應 --

time times velocity equals distance,

時間乘以速率等於距離，

equals one-fifth of a second times 25,000 miles per hour,

等於五分之一秒乘以時速兩萬五千哩，

equals 1.4 miles

等於一點四哩，

- we would have gone past it or through it by over a mile.

我們早就已經超過或撞穿那個事物一英哩了。

We're either going to kill ourselves by crashing into the nearest wall at super speed or, worse, if we're indestructible, we've essentially turned our bodies into missiles that destroy everything in our path.

我們會以超高速度撞進距離最近的牆，殺了自己。更糟的是，如果沒死，身體就會像導彈一樣，摧毀行經道路上的一切事物。

So, long distance travel at 25,000 miles per hour would leave us burning up, covered in bugs, and leaves no time to react.

所以，以時速兩萬五千哩長途疾行，會把自己燒成灰燼、撞上一堆蟲子，而且來不及反應。

What about short bursts to a location we can see with no obstacles in between?

那麼如果是短距離衝刺到一個放眼所及、沒有障礙物的地方呢？

Okay, let's say a bullet is about to hit a beautiful damsel in distress.

這麼假設好了！一顆子彈快要打到一位漂亮、需要幫助的女子。

So, our hero swoops in at super speed, grabs her, and carries her to safety.

而我們的英雄以超高速俯衝去抓住她，把她帶到安全的地方。

That sounds very romantic, but, in reality, that girl will probably suffer more damage from the hero than the bullet if he moved her at super speed.

聽起來很浪漫，但事實上，女孩可能會因爲英雄的快速移動，而遭受比起被子彈打到更大的傷害。

Newton's First Law of Motion deals with inertia, which is the resistance to a change in its state of motion.

牛頓第一運動定律：慣性定律，即對運動狀態變化的阻力。

So, an object will continue moving or staying at the same place unless something changes it.

除非被外力改變，否則物體會持續移動或待在相同地方。

Acceleration is the rate the velocity changes over time.

加速是速率隨著時間的改變。

When the girl at rest, velocity equals zero miles per hour, begins accelerating to reach the speed within seconds, velocity increases rapidly to 25,000 miles per hour, her brain would crash into the side of her skull.

當女孩靜止時，速度等於每小時零英里。接著，速度在數秒內開始飆升，速率快速增加到每小時兩萬五千哩，她的大腦會撞進頭骨一側。

And, when she stops suddenly, velocity decreases rapidly back to zero miles per hour, her brain would crash into the other side of her skull, turning her brain into mush.

而當她突然停下時，速率快速回歸於零，她的大腦會再撞進另一側頭骨，把她大腦撞成糊狀。

The brain is too fragile to handle the sudden movement.

大腦太脆弱，無法承受突然的快速運動。

So is every part of her body, for that matter.

同樣的，身體任何部位都是如此。

Remember, it's not the speed that causes the damage because the astronauts survived Apollo 10,

記住，並不是速度造成了損害，畢竟波羅十號裡的太空人沒有因高速死掉，

it's the acceleration or sudden stop that causes our internal organs to crash into the front of our bodies the way we move forward in a bus when the driver slams on the brakes.

是加速或突然靜止，造成內部器官向前擠壓，就像公車司機猛踩煞車時，我們的身體會往前移一樣。

What the hero did to the girl is mathematically the same as running her over with a space shuttle at maximum speed.

以數學來看，英雄帶著女孩快速移動，就相當用太空梭以最高速輾過她。

She probably died instantly at the point of impact.

她很可能在撞擊當下就死亡了。

He's going to owe this poor girl's family an apology and a big fat compensation check.

英雄將欠下可憐女孩的家人一個道歉，以及龐大的賠償費用。

Oh, and possibly face jail time.

可能還得面對牢獄之災。

Doctors have to carry liability insurance just in case they make a mistake and hurt their patients.

醫生們必須購買責任保險，以防萬一誤診，導致病患受傷。

I wonder how much superhero insurance policy would cost.

真好奇超級英雄的保單費用會有多高。

Now, which superpower physics lesson will you explore next?

那麼，你下一個想要探索的超能力物理課是什麼呢？

Shifting body size and content, super speed, flight, super strength, immortality, and invisibility.

變換身體大小及材質、超高速、飛行、巨大怪力、長生不死和隱形。