You Could Lift Tons—Here’s How!

Ajouté : 2026-06-03

[00:00:09][music] >> Today, we're going to teach you how to knock people into the pool using physical force.

[00:00:21]I mean the force of physics. Seriously now.

[00:00:25]We are going to understand how it's possible to throw people into the pool using physics, but we'll also learn how it's possible to multiply our strength using pulleys, sheaves, or pulley wheels. This rotating piece here, which you've probably [music] seen at construction sites, or this one, which you might have on your clothesline at home. And as a bonus, you'll also get two experiments to do at your science fair. This is really old. Even Archimedes, that guy who said Eureka, the lever guy, used it. One time.

[00:00:51][music] Even showed off to King Hiero, managing to launch a ship weighing several tons into the sea using only the strength of his hands and a system of levers and pulleys. That's where another famous Archimedes phrase originated, "Give me a lever and a place to stand and I will move the world." There are many versions of this phrase online, likely because it was said over 2,200 years ago, giving it plenty of time to change. Not many. But anyway, among the products we developed here at Manual do Mundo with Big Geek, there was this bottle opener that has Archimedes' phrase on it at the same It's a lever. And in the phrase, we use letters that are tools which also use the principle of the lever. Like here, the crowbar, the pliers, and so on. But anyway, how does a little wheel like this manage to multiply my strength? That's kind of strange, right? It seems like infinite energy. One of those fake news things.

[00:01:43]Let's look at the root example. I have these two blocks and together they're pretty heavy. They weigh almost 25 kilos.

[00:01:51]About 24.8, more or less. I'm setting up a pulley system to lift these blocks.

[00:02:00]Oop- Oops, that's right.

[00:02:06]You guys missed a spectacular fall.

[00:02:09]I wanted to make it into the top video bloopers of the decade, but there's no footage.

[00:02:14]Look, here I already have an interesting machine. I can pull down and the block goes up. I'm reversing the direction of the movement. The downside is that I'm using the same amount of force. Let's check it with the force gauge. My force gauge isn't the most accurate, but it's showing about the same thing, 22 24 kilos. Now, let's cut this weight in half, or better yet, let's double the force I'm applying.

[00:02:38]>> [music] >> It leaves the fixed point, goes through one pulley, through another pulley, and I pull.

[00:02:45]It's really easy.

[00:02:47]Really easy. I can do it with one hand.

[00:02:49]It's practically half the previous weight, exactly. But, what's the trick?

[00:02:53]What's the secret here? How can I double the force I can apply, or divide the weight of the block in half? Here's the thing, when I pull the rope in this situation, I pull 1 m of rope, but the block only goes up half a meter. So, it's a trade-off. I only have to use half the force, right? I'm using much less force, but I have to pull a lot more rope. It's like if you were putting 25 kg bags of cement in your car, it's really heavy, but you can split it into two pieces of 12 and 1/2 kilos each. You're still putting in the same amount of cement, but you use much less force, with the trade-off that you'll have to make two trips. In this case, my strength is multiplied by two because I have two ropes here, not counting the rope in my hand, okay?

[00:03:37]If I add another rope, my strength will be multiplied by three, and I do that by adding one more pulley.

[00:03:44]>> [laughter] >> Those 25 kilos have already turned into about eight or so here, but it's tough cuz I'm pulling upwards, right? If I could use my own body weight, it would be even easier. So, let's take the opportunity to add one more pulley.

[00:03:58]Now I have four ropes, which means the weight is divided by four, or that my strength is multiplied by four.

[00:04:04]>> [snorts] >> It's really, really easy.

[00:04:08]But you know that to ask you for a like, I need to offer you a little more, right?

[00:04:15]Ah.

[00:04:16]Ah.

[00:04:19]It's really light.

[00:04:20]It's so light that the friction from the pulley can stop it in midair.

[00:04:25]Was that worth a like now?

[00:04:27]In this case, now I'm using six pulleys and multiplying my force by six. But there's a smarter way to set up this arrangement where I can use fewer pulleys and multiply my force even more times. And the coolest part is that I'm going to demonstrate this in a way that you can do at home and take to your science fair.

[00:04:43]Look at this beautiful little thing we set up here that you can make at home.

[00:04:50]There's a PVC beam that works like our ladder outside. They're really simple connections. We're leaving everything in the video description, so you can make it. Instead of those steel construction pulleys, we have these clothesline pulleys, which are cheaper. We used some hooks to fasten it, and that's basically it with string running through the middle.

[00:05:08]Here, the force multiplication is the same as before, but this time we don't have that tangled mess. You can see all the cables and everything. My force is only being multiplied by six. So, let's keep my promise and do this in a simpler and more efficient way. I went back to the system from the beginning. So here, my force is being multiplied by two. But what if we replace this cable here with another pulley system?

[00:05:31]Ah. Man, look how cute this is.

[00:05:35]Instead of the cable, I have another pulley system. This means that here my force is doubled, and here it's doubled again.

[00:05:42]So, I'm multiplying my force by four using just three pulleys.

[00:05:52]But what if I replaced this little rope here with another pulley system?

[00:05:57]Look at this beauty.

[00:06:00]Four pulleys and my force is multiplied by eight.

[00:06:05]Here it's multiplied by two, then by two again, and by two again. Two times two times two, eight. And of course, as you noticed, I have to pull eight times here for it to go up just a little bit.

[00:06:17]It's going to use a lot of rope. I could keep adding pulley systems here infinitely.

[00:06:21]I don't know. Multiply my force by 256.

[00:06:25]But in this setup I have, notice that the more pulleys I add, the less my weight goes up. I have to pull a lot of rope for it to go up, and I don't have space for that. So, in the setup we have here to multiply the force even more, we would need a much taller beam.

[00:06:40]But hold on. It's time for the prank.

[00:06:43]There's one last experiment you can do at home. It's easier than this one, and you only need two hoe handles and a rope. It has to be hoe handles, okay? If you use broom handles, they might break.

[00:06:53]I'm back with the setup that multiplies the force by six.

[00:06:56]What you're seeing here is a demonstration model, a model that's easy for you to see and understand what's happening. In real life, there are several different ways to make this arrangement. In construction, for example, if you look at a crane, at the end of it, usually there's something like this. But the pulleys are all close together, right? They're not separated like this in the model we're going to make now using a hoe handle. We're going to replace these three pulleys here with a hoe handle, so it's like I'm removing the pulleys and making the rope run directly on the handle.

[00:07:26]We're going to do the same thing on the other side. So, we're going to replace six pulleys with two hoe handles.

[00:07:32]But hold on, because before that, there's something even more important.

[00:07:35]Ana and Laura are going to debut on Manual do Mundo with a series called Tem Ciência, and the idea is that they'll explain some things from our daily lives that involve science and we don't even realize it. The first video we're going to release will be about mixing household chemicals at home. The ones you shouldn't do. You can do that. It won't go wrong.

[00:07:59]Look, the second script that I'm already working on with them, which is really cool, is about whether it's possible that viruses and bacteria thawing out up in northern Russia and northern Canada could come back and cause a new pandemic. Let's not give any spoilers. No. Not that one. That one's really cool.

[00:08:16]Peter, come here. Peter will join the experiment, too. What's the idea?

[00:08:19]The idea is that one of you will be stronger than me and Peter together. So, you're already strong?

[00:08:27]It's training. Yeah. Hold on. Now it's two against one here.

[00:08:33]Three, four. Let's go. What now? Here's the deal. Look, Laura is going to pull and Peter and I are going to try our best not to get close to each other. It's her versus the two of us, but you already know about the pulley in the middle, right? Let's see if it works in practice. Go.

[00:08:51]All right, ready.

[00:08:57]>> [laughter] >> There's no way.

[00:09:05]Possible.

[00:09:07]Go ahead, Laura. I trust you. Let's dance. I'm going to sing.

[00:09:12]Oh my god. You won, Laura.

[00:09:15]No.

[00:09:16]Should we do it with Anna and more passes? You'll get nine times stronger than us.

[00:09:21]The stronger you get, but I think there's too much friction. 4 5 6 7 8 9 10 11. I don't know if it's going to work because there's too much friction with so many ropes. It might not happen.

[00:09:31]Wow.

[00:09:39]I think we're winning.

[00:09:45]That is really strong man.

[00:09:48]There's no way. Wow.

[00:09:50]What an unfair tug of war.

[00:09:52]There's no way.

[00:09:54]That was so easy.

[00:09:55]>> Have you ever heard of a hairbrained idea?

[00:09:57]This is one right here.

[00:10:04]God, I LOVE THIS VIDEO.

[00:10:09]>> [screaming] >> NO, THE MOMENT I SAW THE ROPE SLIPPING, I was sure I was going to fall into the pool and have to fish all my things from the bottom.

[00:10:31]I wouldn't I would let go.

[00:10:34]I'd let go. Let go of Victor, right?

[00:10:36]Come on, Victor.

[00:10:37]>> [laughter] [laughter] >> Let it be noted that I almost won.

[00:10:56]If you want to get strong and not embarrass yourself like Victor, who almost fell into the pool, check out our video where we teach you how to make homemade concrete weights. They're really cheap and worth it.

[00:11:08]>> [music]