ClassX Video Lessons Youtube Channel SmarterEveryDay Why Snatch Blocks are AWESOME (How Pulleys Work) – Smarter Every Day 228
Hey there! Welcome to an exciting lesson about pulleys. Today, we’re going to explore why pulleys, especially snatch blocks, are so amazing. Pulleys are simple machines that help us lift heavy things more easily. They give us something called “mechanical advantage,” which means we can use less force to move something heavy. Let’s dive in and see how they work!
Imagine you have to lift a heavy block. If you try to lift it directly, you have to use a lot of strength. But with a pulley, you can change the direction of the force you apply, making it easier to lift the block. A pulley is like a wheel with a rope around it. When you pull on one side of the rope, the pulley redirects the force, helping you lift the block with less effort.
Now, let’s talk about a special type of pulley called the snatch block. It’s super cool because you can open it up and insert a rope without having to disconnect the rope from whatever it’s attached to. This makes it really handy in tricky situations. Snatch blocks are often used in activities like zip-lining, where you need to move a cable without taking everything apart.
When you use a pulley, you’re using the tension in the rope to your advantage. Tension is the force that pulls on the rope. By arranging pulleys in different ways, you can increase the mechanical advantage. This means you can lift heavier things with less effort. For example, if you have two pulleys, you can double the force you apply, making it twice as easy to lift something.
Let’s say you want to lift a really heavy object. You can use a combination of pulleys, called a block and tackle, to make it even easier. By adding more pulleys, you increase the number of ropes supporting the weight. This means you need less force to lift the object. It’s like having extra hands helping you lift!
Snatch blocks are not just for fun; they can be lifesavers in real situations. For example, if a truck gets stuck, you can use a snatch block to help pull it out. By attaching the snatch block to a tree and running the winch cable through it, you can double the pulling force, making it easier to free the truck.
The concept of pulleys has been around for a long time. Even ancient scientists like Archimedes used pulleys to move heavy objects. By understanding how pulleys work, you can impress others with your knowledge and solve problems more efficiently.
Did you know that pulleys are also used in space? Astronauts use snatch blocks on the Space Shuttle to help move things around when they’re floating in zero gravity. Without gravity to help, pulleys become essential tools for applying force and moving objects.
So, there you have it! Pulleys, especially snatch blocks, are fantastic tools that make lifting heavy things much easier. By understanding how they work, you can use them to your advantage in many situations. Whether you’re lifting a heavy block or helping a friend out of a sticky situation, knowing how to use pulleys can be incredibly helpful. Keep exploring and learning, and you’ll be amazed at what you can do!
Gather some materials like string, spools, and small weights. Create a simple pulley system and experiment with lifting different weights. Observe how adding more pulleys changes the effort needed to lift the weights. Share your findings with the class.
Work in groups to design a scenario where a snatch block could be useful, such as rescuing a toy car stuck in a “mud pit.” Use a snatch block to solve the problem and present your solution to the class, explaining how the snatch block helped.
Take a quiz to test your understanding of pulleys and snatch blocks. Answer questions about mechanical advantage, tension, and real-life applications. Discuss the answers with your classmates to deepen your understanding.
Research how pulleys have been used throughout history and in space exploration. Create a presentation or poster that highlights key uses and innovations. Share your work with the class to showcase the importance of pulleys in different contexts.
Use an online simulation to explore how different pulley configurations affect mechanical advantage. Experiment with single, double, and compound pulley systems. Record your observations and discuss how these systems could be applied in real-world situations.
Sure! Here’s a sanitized version of the transcript:
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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 those 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 clever, and arranges it in the perfect way to make things work, that’s like the smart person that everybody wants to be.
So today, on Smarter Every Day, we’re going to make a video about pulleys, and we’re going to slowly walk through how they work. Specifically, I want to introduce you to my favorite type of pulley; it’s called the snatch block. They’re really fancy and can do tricks.
Okay, let’s start by picking up these cinder blocks. My kids are going to 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? 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.
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 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?
So this is the part that starts to confuse people. If you can change the way the pulleys 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! 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? 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 I can work with them with my hands. So I 3D printed a bunch of pulleys and snatch blocks, and we’re going to 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 want to 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 going to 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 can 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 incredible. 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!
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 were 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 flatbed 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 its 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 they 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.
Oh, I’m so excited; we’re going to do a double snatch block! Oh, this is great! If I’m going to put that one–
– It’s locking on the block?
– Yeah, yeah.
– Okay.
– If you’ll point that direction.
– Yeah, I’ll do it.
I’m going to level with you; Jeff is the kind of guy I want to be when I grow up. Watch how he just picks up a snatch block and starts working. He just knows what to do.
Snatch block engaged.
How many snatch blocks you got?
– About five.
Dude, I’m an amateur; I only got two.
– I got a triple.
You got a triple? Like a–
– A wooden triple block.
A block and tackle?
– Yeah, that’ll work.
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 tricky situation; knowing how to use them can help you make friends, 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?
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.
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 going to snatch block this bad boy out of here!
What you actually want to 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?
– I got the winch.
Okay, here we go. Cut the engine off and put it in gear, and just see if it’ll pull the Jeep.
– And like drag it, okay?
– Yeah, see if it’ll just pull it.
Ready?
– Yeah.
Oh, that’s scary. That’s a lot of force, dude.
– Yeah, man.
That’s good. Dude, that’s a lot of force, man.
– Yeah, man!
Thoughts?
– Alright, man. Snatch blocks are awesome, man.
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 same 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 fewer 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 my 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 going to 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 warship.” And King Hiero’s like, “Yo, dog, here’s your warship.”
And Archimedes is like, “Yo, dog, I hear that you like pulleys. I got pulleys on pulleys on pulleys.” And Archimedes does something amazing. Under his own physical strength, he pulls an entire warship 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 going to 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 them 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 and even outside on a spacewalk.
You’re in a problem; you have a load; you have to pick it up; what do you do? Snatch block!
It’s kind of funnier when it doesn’t work, isn’t it? Snatch block! That is exactly what you want. You want to be the person that knows how to use the snatch block, understands mechanical advantage, and gets your team out of the situation.
There’s a road crew on the side of the road repairing the guardrail with a snatch block.
Thanks, man.
– Yeah, man.
Have a good one.
It was kind of weird; I pulled over and said, “Hey, can I check out your snatch block?” And they were like, “What are you talking about?” Pretty cool, though.
I should get back in my truck.
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This version removes any inappropriate language and maintains the educational content.
Pulleys – A simple machine consisting of a wheel with a groove around its edge, through which a rope or chain can run to change the direction of a force applied to the rope and lift a load. – In our science class, we used pulleys to lift a heavy box with less effort.
Snatch – To quickly seize or grab something, often used in physics to describe a sudden application of force. – The engineer had to snatch the lever to stop the machine in an emergency.
Block – A solid piece of hard material, often used in physics to describe an object that can be moved or lifted using mechanical means. – We used a wooden block to demonstrate how friction affects motion.
Force – A push or pull on an object that can cause it to change its velocity, direction, or shape. – The force applied to the car made it accelerate down the track.
Tension – The force that is transmitted through a string, rope, cable, or wire when it is pulled tight by forces acting from opposite ends. – The tension in the rope increased as more weight was added to the hanging basket.
Mechanical – Relating to machines or the use of machinery, often involving physical forces and motion. – The mechanical advantage of the lever allowed us to lift the heavy rock with ease.
Advantage – A condition or circumstance that puts one in a favorable or superior position, often used in physics to describe the benefit gained by using a simple machine. – By using a pulley system, we gained a mechanical advantage that made lifting the load much easier.
Lift – To raise something to a higher position or level, often using a force or mechanical device. – The crane was used to lift the steel beams to the top of the building.
Rope – A strong, thick line made of long twisted threads, used in physics to transmit force in systems like pulleys. – We tied the rope securely to the sled before pulling it up the hill.
Gravity – The force that attracts a body toward the center of the earth, or toward any other physical body having mass. – Gravity is the reason why objects fall to the ground when dropped.
