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  • I'm about to experience weightlessness

  • for the first time.

  • Oh my god! Oh my god

  • that is so strange *Oh my god*

  • this is totally freaky

  • this is way better than I expected

  • I'm just gonna say that right now

  • *um*

  • I'm going up to the ceiling

  • and here we are.

  • I am ridiculously excited, because behind me

  • is a Zero-G plane.

  • I'm in France, I was invited here by

  • by the youtuber Bruce.

  • This is Bruce, Diana physics girl.

  • We are going - flying some parabolas- we're going into Zero-G

  • It's gonna be awesome! C'mon

  • The principle behind weightlessness is pretty simple,

  • the plane and everything inside it just need to accelerate towards the earth

  • at the same rate as a freely falling object in a vacuum.

  • That is 9.8 meters per second squared

  • So, you can think of your body as this pen, and the plane as this bottle

  • and when it's freely falling, there's no contact force between the pen and the bottle,

  • and so the pen feels weightless.

  • So you might think the way to do this

  • is just to put the plane into a dive.

  • But that's not actually how it works.

  • Instead, the plane starts climbing

  • at a steadily increasing angle.

  • With no windows inside,

  • it's impossible to tell that this is happening,

  • and all you feel is pressed into the floor with a force

  • 1.8 times your body weight.

  • This is because the plane's acceleration is

  • directed upwards and perpendicular to

  • the floor, and it makes standing very

  • difficult - not only are you nearly twice

  • as heavy, all the blood drains from your

  • head and into your feet - which made me

  • pretty dizzy. -Ah!

  • Haha! So weak... ugh -Lying on your back is much

  • more comfortable, and we're advised not

  • to move our heads around and look

  • straight ahead,

  • because in hyper-G our vestibular system

  • is hypersensitive to movement, which can

  • lead to motion sickness. And that's why

  • this is sometimes called the vomit comet.

  • -I kind of like this. -It is fun, feels like

  • someone lying on you -Yeah -Not like that.

  • Once the plane is climbing at about 50

  • degrees,

  • the engines are ramped down, and the

  • plane is put into a parabolic trajectory.

  • It's at this point that you start

  • experiencing weightlessness. -I can feel

  • myself getting lighter... oh that is such a

  • strange feeling... that is so weird...

  • -The plane and you are still moving

  • upward, but you are accelerating downward.

  • -There's Diana, she's the physics girl

  • Then the plane peaks, and start speeding up again towards the Earth.

  • The whole time the plane is accelerating toward Earth

  • with the same acceleration as a free falling object in vacuum,

  • the pilots have to very skillfully adjust the thrust

  • to perfectly balance air resistance, and maintain exactly this acceleration.

  • Oh, my goodness-

  • how do you feel?

  • This is incredible.

  • So, it's like throwing this bottle into the air

  • the pen inside experiences weightlessness

  • from the time it leaves my hand, until it comes into contact again.

  • After 22 seconds of weightlessness, the pilots pull out of the dive

  • again, subjecting us to hyper-g...

  • as the plane accelerate upwards.

  • In total, we have performed thirteen of these zero-g parabolas-

  • plus, one martian gravity and two moon gravity parabolas.

  • Okay, we are now in Mars gravity.

  • In Mars gravity i can do

  • one arm pull ups..

  • maybe.

  • I am the martian.

  • We brought along some experiments to do in zero-g.

  • So, this is in about 1g, of gravity

  • this are what the flame looks like on this barbecue lighter

  • now we are gonna try it in hyper-g?

  • And then we'll try it in zero-g

  • and it should be...

  • We will see... (2x).

  • We take it for granted that flames had this distinctive shape.

  • But that only because of gravity.

  • The products of combustion have more energy

  • and so, move around faster and take up more space than the cooler air around them.

  • Therefore, there is a buoyant force on them, which is greater than their weight-

  • and so, hot air rises.

  • This helps pulling the oxygen from around the flame to continue the reaction.

  • We are going through hyper-g.

  • i keep blowing out the candle, because...

  • The, uhhh... stress of hyper-g is significant.

  • In hyper-g, this effect is magnified.

  • Since the effect of gravity is almost twice as much.

  • This amplifies the difference between the weight of the hot air,

  • and the weight of the cooler air around it-

  • and so, the hot air rises faster...

  • making, a longer flame.

  • Oh my goodness.

  • Look at that flame just...

  • in zero-g 'cause there is...

  • much less buoyant force,

  • to carry away...

  • And so, the combustion is not as good you can see a lot of smoke.

  • coming off, of that candle.

  • And it's incredible.

  • So, we still have a gas flow

  • so this is why the flame is not circular.

  • It is not a sphere, but it looks very strange.

  • In zero-g, the hot air is still less dense than the cooler air...

  • but, now there is no weight,

  • and no buoyant force.

  • So, the flame doesn't rise as high.

  • This flame still maintain some if it shape, because of the flow of fuel from the lighter

  • otherwise, the flame would form a sphere.

  • Like on the space station.

  • Where, it's very difficult to maintain the combustion reaction.

  • because it's hard for oxygen to access the fuel

  • with all of the combustion products getting in the way.

  • So, if you're ever unsure about what the gravitational acceleration is where you are.

  • Well, looking at a flame is a pretty good way of finding out.

  • I also brought along a slinky, to try the slow motion slinky drop

  • but, in zero-g.

  • Of course, here i couldn't dangle the slinky under it's own weight

  • so, i swung it around my head instead.

  • The effect, should be similar with each coils stretch to provide the tension that keeps...

  • the length of slinky beyond that...

  • accelerating in uniform circular motion.

  • I wanted to see what happens to the end of the slinky, when i let go.

  • Here we go, 3, 2, 1.

  • Did you catch that?

  • The slinky remain fairly stretch out,

  • and kept rotating at about the same frequency as before.

  • Initially, i thought this was a boring result.

  • But then i realized...

  • the reason the slinky doesn't contract,

  • is because weight, was never part of this equation.

  • The slinky stretched out in the first place, because it was rotating.

  • And, since it's rotating after i let go...

  • roughly, the same amount of tension is required to maintain that circular motion.

  • And so, it doesn't contract.

  • In zero-g, it's possible to have a stretched slinky rotating in place,

  • without contracting

  • as long as the tension in the slinky provides the centripetal force, it will keep spinning.

  • This just goes against my intuition.

  • Which is, made of course...

  • only had of experiences with gravity.

  • Being weightless, was an unforgettable experience.

  • But, maybe my favorite part,

  • was how it challenged my intuition.

  • And that's the reason, we need to do research, in zero-g.

  • I want to say a huge thanks, to the team at NovaSpace who made this an unforgettable experience.

  • And of course, Bruce who runs a french youtube channel, e-penser for inviting me.

  • You should really go check out his video from the zero-g experience, and of course Diana, the Physics Girl.

  • Go check out her video on zero-g here.

I'm about to experience weightlessness

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B1 中級

ZERO-Gで火事! (Fire in ZERO-G!!)

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    林宜悉 に公開 2021 年 01 月 14 日
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