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  • Some superheros can move faster than the wind.

  • 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.

  • Wouldn't we save a lot of time

  • to be able to move that fast?

  • But what's the catch?

  • Air is not empty.

  • Elements like oxygen and nitrogen,

  • even countless dust particles,

  • make up the air around us.

  • When we move past these things in the air,

  • we're rubbing against them

  • and creating a lot of friction,

  • which results in heat.

  • Just like rubbing your hands together warms them up

  • or rubbing two sticks together makes fire,

  • the faster objects rub together,

  • the more heat is generated.

  • So, if we're running at 25,000 miles per hour,

  • the heat from friction would burn our faces off.

  • 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.

  • Ever seen the front bumper or grill of a truck?

  • What do you think all the birds and bugs would do

  • to your open eyes or exposed skin?

  • Okay, so you'll wear a mask

  • to avoid destroying your face.

  • But what about people in buildings

  • between you and your destination?

  • It takes us approximately one-fifth of a second

  • to react to what we see.

  • By the time we see what is ahead of us

  • and react to it -

  • time times velocity equals distance

  • equals one-fifth of a second

  • times 25,000 miles per hour

  • equals 1.4 miles

  • - we would have gone past it

  • or through it by over a mile.

  • 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.

  • So, long distance travel at 25,000 miles per hour

  • would leave us burning up,

  • covered in bugs,

  • and leaves no time to react.

  • What about short bursts

  • to a location we can see

  • with no obstacles in between?

  • Okay, let's say a bullet

  • is about to hit a beautiful damsel in distress.

  • So, our hero swoops in at super speed,

  • grabs her,

  • and carries her to safety.

  • 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.

  • Newton's First Law of Motion deals with inertia,

  • which is the resistance to a change

  • in its state of motion.

  • So, an object will continue moving

  • or staying at the same place

  • unless something changes it.

  • Acceleration is the rate the velocity changes over time.

  • 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.

  • 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.

  • The brain is too fragile to handle the sudden movement.

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

  • Remember, it's not the speed that causes the damage

  • because the astronauts survived Apollo 10,

  • 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.

  • What the hero did to the girl

  • is mathematically the same as running her over

  • with a space shuttle at maximum speed.

  • She probably died instantly at the point of impact.

  • He's going to owe this poor girl's family an apology

  • and a big fat compensation check.

  • Oh, and possibly face jail time.

  • Doctors have to carry liability insurance

  • just in case they make a mistake and hurt their patients.

  • I wonder how much superhero insurance policy would cost.

  • Now, which superpower physics lesson

  • will you explore next?

  • Shifting body size and content,

  • super speed,

  • flight,

  • super strength,

  • immortality,

  • and

  • invisibility.

Some superheros can move faster than the wind.

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B1 TED-Ed speed velocity hour super rubbing

【TED-Ed】If superpowers were real: Super speed - Joy Lin

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    VoiceTube posted on 2013/11/09
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