最新评论 (0)


Acoustic Levitation in ULTRA SLOW MOTION - Smarter Every Day 134

嘿 是我 德斯廷
Hey it’s me Destin
welcome back to Smarter Every Day.
我在芝加哥 安东尼用他那辆超棒的野马接的我
I am in Chicago. Anthony picked me up in his awesome mustang
and told me to come to this building
because we’re gonna film acoustic levitation.
What, is this?
– This is an acoustic levitator
它是单轴的 这意味着我们只能控制一个轴上的东西
It’s single axis, which means that we only control things on one axis here.
So we have two horns or transducers..
——每当我看到示波器上的显示 我就兴奋
– Any time I see an oscilloscope I get excited.
So am I gonna hear it on the camera?
– You’ll.. so the main frequency we’re using again is 22kHz
which is higher than human hearing.
What you’ll be hearing are sub-harmonic around 17-18kHz.
– But I can just put a low pass filter on the audio and I can..
——你省省吧 好吗?
– I’m guessing that you cut it out, yeah.
– OK
——把它打开…… 在示波器上 你会看到
– Turn it up.. And on the oscilloscope you’ll see
the two waves from each of the two horns. [high pitched erratic noise]
– Well let’s stinking levitate something dude.
是的 那只是一个泡沫塑料球
– Yeah, so that’s just a Styrofoam ball.
勺子有这样的槽缝 所以声音能通过它
And the spoon has all those slots and so sound passes right through it.
——不可能 通过这声音 你认为是压力
– No way. And by sound you mean pressure.
——是的 这声波就是我说的压力波
– Yeah the sound waves, which are pressure waves I mean.
But you can see the wave length spacing basically between these.
– That’s stinking awesome.
You may have seen sound drawn like this.
But it’s a bit too simplified.
A real sound wave actually looks like this.
明亮部分是高压力 深色部分是低压力
The bright parts are the higher pressure and the darker parts are the low pressure.
These ripples move along at the speed of sound.
当你有两段相同的声波 并让它们正面相对
When you have two identical sound waves and you line them up just right
they no longer act like waves moving across the room.
If you have a wave coming from this side,
and another wave coming from the other side,
they become what’s called a standing wave.
然后会有一个点 在那里压力不断地翻转又平息
You get a spot right here where there’s a pressure flipping on and off,
and a spot right here where the pressure isn’t changing at all,
there’s no oscillation.
如果你把这垂直向上翻转 然后把这些小东西放进那个小容器里
If you flip this thing upright, and then you put something tiny right inside that little pocket,
你就可以利用气压 克服重力 把物体升起
you can use that air pressure to bump something up against the force of gravity.
So it ends up looking like this ping pong paddle.
粒子想下降 但它继续被
The particle wants to drop but it keeps getting knocked back up
by the high pressure wave below it.
And that is acoustic levitation.
那么如果它对泡沫球起作用 那它对水也会起作用 对吧?
So if it works with foam it should work with water, right?
Anthony uses a syringe to balance little drops of water on top of that oscillating wave.
就像乒乓球一样 你可以看到它上下弹跳
Just like the ping pong ball you can see it bouncing up and down.
看看底部的那个 跳上跳下试图找到它的位置
Look at the one on the bottom, bouncing up and down trying to find its spot.
另一个很酷的事情是 如果我把水滴弄得太大
Another cool thing is the fact that if I make the water drops too big
they always seem to explode.
Why would it do that?
它发生得有点太快 肉眼看不见
It happens just a little too fast to see with the naked eye.
我飞回家 希望能找到一些办法把声波悬浮机和高速摄影机结合在一起
I flew home wishing I had some way of bringing together the acoustic levitation machine and a high speed camera.
Ten months went by.
我没有办法做到这一点 但后来我接到福特的电话
I had no way of doing this, but then I got a call from Ford.
They wanted to know if I could do any sound experiments on American Idol out in Hollywood.
我们有两个小时 这是我工作以来最惊人的工作环境
We have two hours with the most amazing setup I’ve ever worked with,
an ultrasonic levitation device and two really fast high speed cameras.
We’re gonna do 20,000 frames per second with the V2511
and we’re gonna do 7,500 frames per second with the V711.
I didn’t want to just make a TV segment.
我真的想和这些家伙在一起 教他们一些关于声音的新东西
I actually wanted to hang out with these guys and teach them something new about sound.
——嗨 我是贾克斯
– Hi I’m Jax.
– I’m Rayvon.
– I’m Clark.
– I’m Tyanna
– I’m Nick.
——好吧 我们不会假装这些家伙不知道发生了什么事
– Alright, so we’re not gonna pretend like these guys don’t know what’s up
因为我们已经做了一部分 实际上他们……
because we’ve already done a segment and they’re actually..
你现在知道它是如何工作的 是吧?
You know how this works now right?
——是的 【所有人都同意】
– Yeah. [all agree]
——好的 过来这边让我展示给你们它是怎么工作的
– OK. Come over here and let’s show everybody how it works.
——对我来说 它就像是电吉他
– It looks to me like just an amp.
– OK.
– And when I turn up the amplitude, sound waves through the horns
通过角的声波会互相撞击 形成一个声柱
will come down against each other and will make a column
where you can actually suspend liquid or things of physical..
——【笑声】 是的 那是对的 那是对的
– [laughter] Yes, that’s right, that’s right.
(Destin) Did he get it right?
– I think he did.
——有一个方程式可以算出实验要用的最大的雨滴有多大 好吗?
– There’s an equation that dictates how big a raindrop can be, OK.
So the pressure that’s on the inside of the drop is determined by two times
the surface tension divided by the radius.
如果水滴太大 会发生什么?
If the drop gets too big, what happens?
– It explodes.
是的 会爆炸 我们先记录漂浮的水滴的高速视频
– It explodes. We’re recording high speed video of these drops that we’re levitating,
and then we’re ramping up the amplitude
这和改变压强是一样的 对吧
which is the same as changing the pressure, right?
所以 一旦我们那样做 压力就会变得非常大
So once we do that, the pressure gets so great
that the surface tension can’t hold the drop together any more
and then it just ruptures.
内部压力小于外部压力 它就会爆炸
It overcomes that internal pressure and you get an explosion.
好吧 我希望你喜欢这一期的《机灵日》
Alright I hope you enjoyed this episode of Smarter Every Day.
I’m not obligated to say anything about any product
但福特是非常棒的 真的 他们让我做这不可思议的科学实验
but Ford was awesome, seriously, they let me do awesome science
还是在国家电视台 他们做到了这一切
on national TV and they made all that happen.
非常感谢福特 我很感激
So thank you very much Ford, I appreciate that.
另外 我不需要在机场拿到福特福克斯
Also, I did not have to get a Ford Focus at the airport
但我想试试 我很高兴这样做
but I wanted to check it out, and I’m happy with it.
所以 你懂的
So, there you go.
请支持福特 他们是《机灵日》的支持者
Please support Ford. They supported Smarter Every Day.
我并不是必须要说这些 我希望你们相信我
I don’t have to say that. I hope you believe me.
另外 如果你有收获 请考虑订阅
Also, please consider subscribing if you learned something,
or checking us out at Smarter Every Day on Patreon.
我是德斯廷 你每天都在更聪明
I’m Destin, you’re getting Smarter Every Day.
Have a good one.
我支持你 好吧 教我点别的吧
I’m with you. OK teach me something else.
——那么 一件很酷的事 如果我把手放在下面 我就可以把它们都拿出来
– So one kind of cool thing, if I put my hand under I take them all out.
My hand blocks the sound.
(Destin) What could you be possibly doing that’s more important than acoustic levitation?