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  • (♪Intro♪)

  • Squeaks and I had an interesting adventure this morning.

  • Last night, it was snowing when we went to sleep, and when we got up today there was

  • a bunch of snow on the ground!

  • There's this great hill in the park behind the Fort, and Squeaks wanted to go sledding.

  • So we went out there, pulled our sled up to the top of the hill, and pushed off.

  • We started to move a little bit, but then, before we could get very farwe stopped!

  • Now, I don't know about you, but to me that seems like kind of a silly sled ride.

  • We barely moved before we got stuck in the snow!

  • What do you think, Squeaks?

  • [Squeaks squeaks]

  • Yeah, it was kind of disappointing

  • But even though our sled ride this morning didn't work so well, I bet we can find a

  • way to have an awesome sled ride when we go back to the park.

  • Because with science, we can figure out why we went so slow, and how to get ourselves

  • zooming down the hill instead!

  • When we're sledding, we want to move forward as fast as we can.

  • And there are a couple of easy ways to help ourselves do just that.

  • One thing we can do is push off really hard at the top of the hill to give ourselves more

  • speed right from the start.

  • We can also have more weight on the sled, which will keep us going for longer before

  • we stoplike how it's much harder to stop a heavy bowling ball that's rolling

  • toward you than it is to stop a lighter soccer ball.

  • [Squeaks squeaks]

  • That's true, Squeaks!

  • We were already doing both of those things this morning.

  • We pushed off really hard at the top of the hill, and with Squeaks and I both on the sled,

  • there was plenty of weight to keep going.

  • But that wasn't enough!

  • We still didn't move very fast, and we stopped pretty soon after we started moving.

  • That's because there was something that was slowing us downit was pushing back

  • on us and stopping us from moving forward.

  • Something that pushes or pulls is called a force, and the force that was stopping us

  • from zooming down the hill is called friction.

  • Friction is what makes it hard to slide things across each other.

  • There's lots of friction if those things are rough, and less if they're smooth.

  • Have you ever noticed that when you're wearing socks, it's much harder to slide your feet

  • across carpet than it is to slide then across a wood floor?

  • That's because of friction.

  • Carpet is pretty rough, so there's more friction between your socks and the carpet

  • than between your socks and the smooth wood.

  • The force of friction pushes hard against your socks as you try to slide them across

  • the carpet.

  • And the same thing happened with our sled, Squeaks!

  • Our sled is made of wood, so it's pretty smooth.

  • But the fresh snow from last night is still soft and powdery, and that was making it hard

  • for our sled to slide across it.

  • Instead, the snow kinda bunched up underneath us, and there was lots of friction slowing

  • us down after we pushed off.

  • That's why we didn't go very fast or far before we stopped.

  • So, Squeaks, if we want to go really fast next time, what do you think we should do?

  • [Squeaks squeaks]

  • That would be one way to do it!

  • We could wait a few days until the snow on the ground is much more packed down, so it'll

  • be hard and smooth.

  • But we could also just pack it down now!

  • We can go back to the hill and stomp on the snow for a while, then smooth it out to make

  • a nice track of hard, packed-down snow for our sled.

  • It'll be a little more work before we can start sledding, but I think it'll be worth

  • it!

  • How about you, Squeaks?

  • [Squeaks squeaks]

  • OK, let's do it!

  • (♪♪♪)

  • Wow, that was awesome!

  • We went back to the hill with our sled and ran around on the snow for a while to pack

  • it down into a smooth track.

  • Then, we went up to the top of the hill, pushed off, andzoomed all the way down to the

  • bottom!

  • With the smooth, hard snow, there wasn't as much friction pushing back on the sled

  • after we pushed off.

  • So we kept going faster and faster!

  • [Squeaks squeaks]

  • Yeah!

  • Let's go do it again!

  • Thanks for joining us!

  • If you want to keep learning and having fun with Squeaks and me, hit the subscribe button,

  • and we'll see you next time here at the Fort!

  • (♪Outro♪)

(♪Intro♪)

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B1 中級 美國腔

有史以来最快的雪橇之旅!(The Fastest Sled Ride Ever!)

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    joey joey 發佈於 2021 年 05 月 07 日
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