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  • - Hey, it's me, Destin.

  • Welcome back to Smarter Every Day.

  • It's time for the pulley episode.

  • These are like my favorite things in the whole world.

  • I bought this one, it looks like it goes to a boat

  • or something like that.

  • Pulleys are one of these things

  • that everybody knows about.

  • They know that somehow, a pulley will

  • give you mechanical advantage,

  • but people don't really understand it.

  • We all pretend like we do, but the person

  • that really shows up, and is really clever,

  • and they arrange it in the perfect way

  • and they just make things work,

  • that's like the smart person that everybody wants to be.

  • So today, on Smarter Every Day,

  • we're gonna make a video about pulleys,

  • and we're gonna slowly walk through how they work.

  • And specifically, I wanna introduce you

  • to my favorite type of pulley, it's called the snatch block.

  • They're really fancy, they can do tricks.

  • Okay, let's start by picking up these cinder blocks.

  • My kids are gonna show you how to pick up blocks, right?

  • If you have to pick something up,

  • you have to pick up all of the weight of the thing,

  • and, whether you know it or not,

  • all of the weight of you.

  • How you doing, good? - Good.

  • - You can put it back down.

  • How hard was that?

  • Not that bad?

  • The magic of a pulley is really the magic of a rope,

  • because a rope is always in tension, you can't push a rope.

  • If you pull on this side of the rope,

  • that force transfers all the way through the pulley,

  • so you basically can redirect the force.

  • That is the primary function of a pulley, redirecting force.

  • (child grunts) That's pretty good,

  • how was it?

  • - Hard.

  • - The pulley changes the direction of your body weight,

  • so you can use your own body weight

  • to help you pick something up.

  • Very good, was that hard?

  • Not as hard. - Not as hard.

  • - Not as hard as what? - Just picking it up.

  • - Okay, so it's easier to pick it up with the pulley

  • because you can kind of lean into it, right?

  • - Yes sir. - Right.

  • - So this is the part that starts to confuse people.

  • If you can change the way the pulley are arranged,

  • you can make it even easier to pick this up.

  • Do you want the normal pulley, or the snatch block?

  • - The snatch block. - Snatch block!

  • There you go. (pulley clacking)

  • Go for it.

  • So you split it apart, don't cut your finger off there,

  • there you go.

  • So this is the magic of a snatch block.

  • We can put a pulley in any place at any time

  • as long as there's a rope, and the snatch block

  • is big enough for the rope.

  • This is the part where when you see it happen,

  • you're like, "Oh yeah, of course it's easier,

  • "because of pulleys."

  • But if you don't stop and think,

  • you won't really understand what's happening.

  • So slowly pull, is it really easy this time?

  • - It's a lot more easy. - A lot easier, okay.

  • So, this is what's happening:

  • the tension in the rope right here

  • is being redirected by this pulley

  • because that's what pulleys do, they redirect force.

  • But down here with the snatch block,

  • we're doing the same thing, we're redirecting the force.

  • But you have tension in the rope, and tension in the rope.

  • So all you do is you put tension in a rope somewhere,

  • and then you add up as many ropes as possible on the thing,

  • and that's how you get mechanical advantage.

  • So in this case, how much force is on the cinder blocks,

  • do you know?

  • - Two.

  • - Two times the tension.

  • I don't know about you, but I understand things a lot better

  • if you can work with it with my hands.

  • So I 3D printed a bunch of pulleys and snatch blocks,

  • and we're gonna rig these things up and generate a model

  • of how we were picking up those cinder blocks.

  • When I pull on this rope, that tension transmits itself

  • all the way through the rope to the very end.

  • Wherever the rope is, there's also tension.

  • If I pull here, think about the word pulley,

  • it pulls on the rope on the other side

  • of the pulley right there.

  • That pulls on the rope there at the bottom,

  • which then pulls on the rope on the other side

  • of that pulley, which ultimately pulls against

  • that hook at the very end.

  • All of the ropes are in tension.

  • Now, if you look down there at the cinder block,

  • you'll notice that there are two arrows

  • pulling up on that pulley.

  • That's why we get twice the force on the cinder blocks.

  • But what if we wanna pull harder?

  • Can we just add more ropes and tension?

  • Yes, we can using this.

  • It's basically a double pulley.

  • Some people call this a block and tackle.

  • Instead of two ropes pulling down here, we get four.

  • Just a little bit of force here, even with my pinky finger,

  • that's like 10 pounds of force

  • by just barely pulling at all.

  • This is the same number of ropes,

  • and pulleys and everything, it's just flattened out

  • so we can see what's going on.

  • So, I've got a scale.

  • I'm gonna attach a scale to the input of the rope,

  • and remember, if we put input tension,

  • that tension goes all the way through.

  • So as I pull here, I have one, two, three, four ropes

  • connected to the thing we're pulling.

  • So if I put two pounds here, look at that,

  • I get eight pounds on the output.

  • That's awesome!

  • I'm getting four times the force,

  • but I'm only moving it 1/4th as far.

  • How far do you think we an go with this?

  • You think we can double it again?

  • So now we have two blocks with four pulleys each,

  • which if you count all those up,

  • one, two, three, four, five, six, seven, eight,

  • we have eight ropes in tension on that block.

  • So as I pull here, look at this, that's nuts.

  • That is a little bit of force, and a lot of output.

  • That is some serious mechanical advantage.

  • Look at this though, the ropes over close to me

  • are moving a lot, but the ones over near you

  • aren't moving as much.

  • Let's break this thing apart again,

  • and see if we can understand what's happening.

  • This is so awesome! (board clunks)

  • Oh man, that's a great shot!

  • Okay, so here's what we got: we've got one input pulley,

  • let's count up the tension again,

  • one, two, three, four, five, six, seven, eight.

  • I put two pounds here on the input.

  • Oh, that is a lot of force on the output.

  • Do you remember on the block and tackle,

  • the ropes we're moving at different rates?

  • Well, think about this.

  • On this side over here, that rope is tied up there.

  • It's not going to move.

  • On this side, I'm pulling the rope.

  • It has to move as much as I pull it,

  • and the same is true for this one,

  • because it's just redirecting that string.

  • But after that, everything is affected

  • by how much this moves.

  • So, just playing around with it here,

  • you can see that these ropes move a whole lot more

  • than that one over there that doesn't move at all.

  • There's a lot going on here.

  • Not this is the sort of thing that, yes,

  • you can probably explain it with words,

  • but if you have a fundamental understanding

  • of how this stuff works, and you just know how to use it

  • to your advantage, you can get yourself

  • out of some really interesting situations.

  • For example, the other day, the driveshaft broke

  • on my buddy, Jeremy's truck, and we had to figure out

  • how to get his truck up onto a flat bed trailer

  • without a winch.

  • Snatch block!

  • We rigged up a pulley system so that we could pull

  • his entire truck up onto the trailer

  • using only ratchet straps.

  • We figured it out, but because we were

  • trading force for distance, it was taking forever.

  • That's when a nice guy named Jeff showed up.

  • He drove up, offered to help, and instantly understood

  • our pulley system, and knew what to do with this truck.

  • We disconnected one of the ratchets,

  • put Jeff's truck in it's place,

  • and pulled this truck up until the rope hit the trailer.

  • One thing I love about Alabama is nice people like Jeff

  • just stop and help you, and the instantly know

  • what's going on.

  • For example, watch how quickly Jeff figures out

  • all the mechanics once I tell him

  • we have an extra snatch block.

  • (engine idling) Oh, I'm so excited,

  • we're gonna do a double snatch block!

  • Oh, this is great!

  • Is I'm gonna put that one-- - It's locking on the block?

  • - Yeah, yeah. - Okay.

  • - If you'll point that direction.

  • - Yeah, I'll do it.

  • - [Destin] I'm gonna level with you,

  • Jeff is the kind of guy I wanna be when I grow up.

  • Watch how he just picks up a snatch block

  • and starts working.

  • He just knows what to do.

  • Also, his hands are just amazing.

  • Watch this man work.

  • (engine idling)

  • Snatch block engaged. (Jeff chuckles)

  • How many snatch blocks you got?

  • - [Jeff] About five.

  • - [Destin] Dude, I'm a amateur, I only got two.

  • (Jeff laughs)

  • - [Jeff] I got a triple.

  • - [Destin] You got a triple?

  • Like a-- - A wooden triple block.

  • - [Destin] A block and tackle?

  • - Yeah, that'll work. (chains clang)

  • - Oh, dude, that's a thing of beauty, my friend!

  • Any day you can use a snatch block is a good day.

  • So yeah, snatch blocks can get you out of a hairy situation,

  • knowing how to use them can help you make friends,

  • thank you so much dude,

  • and they can also be a ton of fun.

  • Zip lines are basically just snatch blocks.

  • You have the ability to break apart the pulley

  • and you can insert a cable into it

  • without having to disconnect the cable from either end.

  • That's essentially the definition of a snatch block,

  • a pulley where you can insert a line

  • without having to take apart your line

  • from whatever it's hooked to.

  • Snatch blocks are amazing, and where else

  • can you get amazing views of the rainforest canopy

  • like this without having a snatch block?

  • (fast forward zip lining)

  • (pulley clanging)

  • Muy bien. - Amigo.

  • (metal clanging)

  • Can you hold this, then? - Si.

  • That's awesome! (girl chuckles)

  • (Jeep engine roars) (grasses rustling)

  • Okay, so you can do a video about snatch blocks

  • without getting a Jeep stuck, so let's go do that.

  • Let's say you got the Jeep stuck.

  • You might be tempted to find the nearest tree,

  • pull the winch out, and pull the cable

  • directly to that tree.

  • What do you think, Jeremy, winch is the way to go?

  • - Winch is the way, well, a snatch block is the way to go.

  • (men laugh heartily) - Good answer, good answer!

  • If we pull that winch out directly to that tree,

  • we would only be able to pull the Jeep

  • with the force that that winch is able to apply.

  • Snatch block!

  • We're gonna snatch block this bad boy out of here!

  • What you actually wanna do is put the snatch block

  • on the tree side, then take that hook,

  • and you hook it back to the Jeep,

  • and so you have twice the pulling force

  • with your snatch block.

  • Alright, you got the winch, right?

  • (engine idling) - I got the winch.

  • - [Destin] Okay, here we go.

  • Cut the engine off and put it in gear,

  • and just see if it'll pull the Jeep.

  • - [Jeremy] And like drag it, okay?

  • - Yeah, see if it'll just pull it.

  • - Ready? - Yeah.

  • (cable motor running)

  • Oh, that's scary.

  • That's a lot of force, dude.

  • - [Jeremy] Yeah, man.

  • (cable motor running)

  • - That's good.

  • Dude, that's a lot of force, man.

  • - [Jeremy] Yeah, man!

  • - Thoughts? - Alright, man.

  • Snatch blocks are awesome, man.

  • (men laugh)

  • - There's a type of pulley system

  • we haven't talked about yet, it's a compound pulley system.

  • You remember the block and tackle,

  • we had an eight-to-one mechanical advantage?

  • Well, this has the some mechanical advantage,

  • but it does it a different way.

  • You remember we add up the tension on these ropes,

  • and we have one plus one is equal to two?

  • But if we have two plus two, it's equal to four,

  • and four plus four is equal to eight,

  • we can come up with an eight-to-one mechanical advantage

  • just like that with less pulleys.

  • This is fascinating, and one of the first people

  • to come up with this concept is a guy named Archimedes.

  • To learn more about Archimedes,

  • I went to make local library, and got a book

  • by a man named Plutarch, who mentions an interaction

  • between Archimedes and King Hiero of Syracuse.

  • It's a really interesting story,

  • but it's gonna be even better if I tell it to you

  • with this flannel board.

  • So it goes like this: Archimedes writes a letter

  • to King Hiero of Syracuse, and he's like,

  • "Yo, King Hiero, I'm really good with pulleys and stuff."

  • And Hiero's like, "Why don't you prove it?"

  • And Archimedes is like, "Well, I will

  • "if you give me a war ship."

  • And King Hiero's like, "Yo, dog, here's your war ship."

  • And the Archimedes is like, "Yo, dog,

  • "I hear that you like pulleys.

  • "I got pulleys on pulleys on pulleys."

  • And the Archimedes does something amazing.

  • Under his own physical strength, he pulls an entire war ship

  • out of the dock, which totally impresses the king

  • because that's what happens when you know

  • how to use pulleys, you impress people.

  • So people have been using pulleys and snatch blocks

  • for thousands of years, and they've been impressed,

  • all the way back in the day with Archimedes.

  • But they're gonna be used for thousands more.

  • That's why you need to know how to use a snatch block.

  • Don't take my word for it though,

  • I'll let Veteran Astronaut Commander Chris Hadfield

  • explain it from his point of view.

  • - The biggest difference between being on Earth

  • and being in space is that you're weightless,

  • and when you're floating around weightless,

  • like on the Space Shuttle, it's really hard to get leverage.

  • You can't dig your feet in,

  • you can't use the weight of things to hold 'em in place.

  • So having a way to hook on one end and hook on the other end

  • and apply a steadily increasing force is really important.

  • And that's why on board the Space Shuttle,

  • we have snatch blocks.

  • They're part of normal equipment.

  • In fact, there's a special stowage block for them

  • that contains a couple, and they get used pretty regularly,

  • both inside the ship, an even outside on a space walk.

  • You're in a problem, you have a load,

  • you have to pick it up, what do you do?

  • Snatch block!

  • (metal clanging)

  • (Destin laughs) (girl laughs)

  • It's kind of funnier when it doesn't work, isn't it?

  • Snatch block! (metal clanging)

  • Snatch block!

  • That is exactly what you want.

  • You wanna be the person that knows

  • how to use the snatch block,

  • understands mechanical advantage,

  • and gets your team out of the situation.

  • Snatch block!

  • Snatch blocks are amazing.

  • I wanna tell you something else that's amazing,

  • and that is the sponsor for this video, which is Kiwi Co.

  • Kiwi Co is like having pure curiosity mailed to your house

  • to ignite the mind of a child every month.

  • And recently, I got to take my boys to headquarters,

  • and we got to meet the people that design the kits.

  • The boys gave them feedback on what it was like

  • to build and play with each one of these kits.

  • In one case, my oldest son collaborated directly with Rebeka

  • whose a kit designer to troubleshoot something

  • she was working on.

  • - But you pull this up, and so like,

  • the plane that hits that instead of your hand.

  • - [Destin] In a matter of seconds,

  • she prototyped his proposed solutions

  • out of toothpicks and string, and they tested it out,

  • and it worked.

  • - Yeah!

  • - This was a really big moment

  • in his life. (Rebeka chuckles)

  • It was super fun meeting these designers,

  • and seeing how they come up with

  • all the different ideas for the kits,

  • and how they make these really clear guides

  • that go in the box so the kids can make these things.

  • These kits are incredible.

  • They teach kids all kinds of subjects,

  • like mechanics, optics, geography, art.

  • There's a specific kit that is an ideal match

  • for any kid in your life who you love,

  • and you wanna inspire to be more curious and creative.

  • I love this company, I'm very proud

  • that they're a sponsor of Smarter Every Day,

  • and they just have a lot of heart,

  • and I think that's very evident

  • if you meet Sandra, the Founder and CEO.

  • Can I ambush you in your office?

  • - Absolutely. - And ask you some questions?

  • - Yes. - Let's go.

  • Where's your office?

  • - My office? - Yeah.

  • - I don't have an office, I have a desk.

  • - Can we go to your desk. - Sure (laughs).

  • - Okay, you don't have an office?

  • You're the boss.

  • - We have an open office environment.

  • - [Destin] So why did you start Kiwi Co?

  • Now, you're an engineer yourself, right?

  • - I am an engineer.

  • I grew up making a lot of stuff,

  • and once my oldest two kids got to a point

  • where I wanted them to start making stuff,

  • I started to compile materials and ideas.

  • And one of my friends was like, "This is so much fun.

  • "You should start a business around this."

  • Yes (chuckles)! - So you created this company

  • as a fusion between parenting

  • and the desire to have your kids tinker?

  • - Exactly, I wanted them to be hands-on,

  • I wanted them to see themselves as people

  • who could create things.

  • I hope these kids grow up not only

  • to be scientists and engineers,

  • but people who do make a positive difference in the world.

  • So I think that has been really great,

  • and hearing about the quality time

  • that people spend with their kids.

  • We want kids, and families, and parents

  • to come away from the experience with Kiwi Co,

  • and just be like, "Whoa, awesome!"

  • That discovery, excitement, fun, wonder,

  • hopefully all that packaged in a box,

  • (laughs) and that gets delivered

  • to your door. - Literally in a box.

  • - Exactly.

  • - [Destin] Thank you so much

  • for making this company. - Yeah!

  • Of course, my pleasure!

  • Thank you for your support.

  • - [Destin] Oh yeah, do you remember how we started?

  • - No. - You don't know how

  • we started. (Sandra laughs)

  • I called the company before you did anything on the internet

  • and I asked if I could sell your products online,

  • before you had ever worked with any influencers or anything.

  • - We so appreciate that.

  • - [Destin] It was really good,

  • it was really good. - No, we really,

  • really appreciate that.

  • - Do you know what the promo is?

  • - Yeah, you get a free crate!

  • - You get a free crate? - Yeah!

  • - [Destin] That's awesome!

  • - That's what you get.

  • - [Destin] KiwiCo.com/smarter, right?

  • - [Sandra] That's right, and we'll send you a free crate.

  • Any line you want, you pick.

  • - [Destin] And people get to pick,

  • and you're gonna send it to them yourself.

  • - Abs, what? (both laugh)

  • What are you signing me up for (laughs)?

  • - You're gonna have the team do it.

  • - We will send it out to you.

  • - There you go, KiwiCo.com/smarter, get a free crate,

  • pick out the line that's best for your child,

  • or in the case of a Eureka Crate, what's best for you.

  • So, that's awesome.

  • Thanks for your time.

  • - Yeah, absolutely.

  • - Thanks. - Thank you.

  • - I'm Destin, you're getting Smarter Every Day.

  • Have a good one, bye.

  • (speeding traffic)

  • There's a road crew on the side of the road

  • repairing the guard rail with a snatch block.

  • (speeding traffic)

  • Thanks, man.

  • - Yeah, man. - Have a good one.

  • - [Crew Man] You, too.

  • - (chuckles) It was kind of weird, I pulled over and said,

  • "Hey, can I check out your snatch block?"

  • (laughs) And they we're like, "What are you talking about?"

  • (laughs) Pretty cool, though.

  • (speeding traffic)

  • I should get back in my truck.

- Hey, it's me, Destin.

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    林宜悉 發佈於 2021 年 01 月 14 日
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