## Subtitles section Play video

• Hey it's me Destin, welcome back to Smarter Every Day.

• So today we're in the rocket van and I've got two little science helpers here right?

• Kids: Yes, right.

• Are you wearing your seatbelts?

• Yes.

• OK we're gonna do something pretty interesting. Check this out.

• I've got a pendulum suspended from the top of our family van

• and we're just gonna drive forward, we're gonna accelerate,

• so if we're going that way, which direction do you think this pendulum should go? What do you think?

• 3.. 2.. 1.. Go.

• Kids: Yes.

• Which way is it going?

• Kids: My way.

• That's right. It's because I'm accelerating right?

• Does that make sense to you guys?

• Yes sir.

• OK very good, I was hoping it would make sense.

• So we're gonna change it up just a little bit.

• OK so now what I'm gonna do is I'm gonna replace this pendulum with a balloon.

• We should see the same thing right? Let me cut this off.

• So what we're gonna do is we're gonna accelerate that way

• so we have the mass of the balloon and the acceleration that should net in a force and will have to react with this string right?

• You guys ready?

• Yes sir.

• 3.. 2.. 1.. Go.

• Wait a second. What just happened?

• What happens when I stop?

• The balloon goes backwards when I stop.

• What's happening?

• 3.. 2.. 1..Go.

• There it is. It's coming right at me.

• Why's it doing that?

• Do you wanna know?

• Yeah.

• Alright, I brought something to show you.

• You remember I told you I was gonna bring this jar earlier? Remember that?

• So it's like this. Imagine this entire van is just like this jar,

• and all the air inside this van is just like the water in the jar. Does that make sense?

• So let's imagine that the balloon is this bubble on top,

• because the helium in the balloon is lighter than air right?

• So that causes it to do what?

• Kids: Go up.

• Go up, that's right.

• So if I've got this air that's just like it, what happens if I move the jar that way?

• All that water sloshes to the back.

• And when that water sloshes back this way, which direction does the bubble go?

• You see that? So the air bubble moves in the direction of acceleration,

• does that make sense?

• I know you're five but I think you can get this.

• OK so I've got my seatbelt on. If I drive forward real fast right now which direction is the balloon gonna go?

• Forward.

• Why will it go forward?

• Because all the air's sloshing back.

• That's right! Very good! Watch this.

• Look at that. You see that?

• So you know what that means don't you?

• That means you have more air to breathe than daddy does when I'm going fast.

• Did you realise that?

• Kids: Nooo!

• Yeah that means when I go fast, that means more air sloshes back there to you and you have more oxygen to breathe.

• Doesn't it feel good back there?

• OK so now we have the plumb bob right next to the balloon, so if I go forward they should spread apart right?

• Let's check it out.

• Is it working?

• Kids: Yeah.

• So what I want to do is I want to tell everybody on Smarter Every Day that if they go download

• a free audio book that it'll help Smarter Every Day by sponsoring us.

• Audible will, if they go to audible.com/smarter.

• And so they get a free audio book, but I'm gonna do it in a funny way.

• Now lean in towards me and look straight at the camera.

• I know you don't know what I'm gonna do but don't laugh

• because I want people to realize that they can send you to school if they get a audio book.

• Does that make sense?

• Yeah.

• So whatever happens don't laugh. OK?

• Look straight at the camera. Ready?

• You don't know what I'm doing, do you?

• OK you ready?

• (High pitched helium voice) Thank you for supporting Smarter Every Day and if you would please download an audio book at audible.com/smarter.

• Did you know daddy could talk like this?

• No.

• You didn't know that happened, did you?

• So if you go get a free audio book it'll support Smarter Every Day and it'll help me send these kids to school.

• Does that sound like a good idea?

• Yes.

• You should never do that, by the way. That's only for adults.

• How'd you do that?

• It's magical. Anyway I'm Destin, you're getting Smarter Every Day.

• Please subscribe to Smarter Every Day and support our sponsor audible,

• I'll leave a link somewhere and you can check it out.

• Thanks, bye.

• How'd you change your voice?

• OK now we have the sunroof, the side window and the back open.

• I'm gonna go forward, where do you think it's gonna go?

• Daughter: Forward.

• Son: Backwards.

• 3.. 2.. 1..

• Dad: So this is air, not helium?

• Yes sir.

• OK I think it's gonna act like the pendulum.

• Dad: 3.. 2.. 1.. Go.

• (laughs) Backwards.

• Oh it does. We're gonna use that one.

Hey it's me Destin, welcome back to Smarter Every Day.

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B1 smarter balloon audio book pendulum audible audio

# A Baffling Balloon Behavior - Smarter Every Day 113

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黃翊丞 posted on 2014/05/11
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