Materials in football

- [Instructor] So in this video I want to talk about a couple different kinds of materials we use to make things. Those three types of materials are animal and plant materials. Another kind is metals, and then a third type of material is called a polymer, and so before talking about these individually, let's talk about one application that we might want to use these materials for, and then that will help us understand why we would do different sorts of things with those materials. So the example in this video is football pads. So this person is tackling this other person right and there's some force on his shoulders here and the pad is there to do two things really. One thing, is to spread the force of the impact across his shoulders rather than hitting in one spot, it spreads it over a larger area. So the first thing, is to spread out the force and that just makes the actual size of the force that's applied in any given area smaller. So it helps protect him, and the second thing is that there's padding in it. It's squishy, squishing, I accidentally wrote squishing instead of squishy but that works, and what the squishing does is it makes the impact take longer it increases the amount of time. Increases time and what that does it also reduces the force. But instead of by spreading it out, it spreads it out over time and so the maximum force at any given moment is actually smaller. So these are two different ways that pads are able to protect somebody and reduce the force that their body is experiencing. Okay so let's look at some materials and think about how they help us accomplish these different goals. So the first type of material I want to talk about is this animal and plant type of material. These are things that we can get from nature and don't have to do too much to use them and they've been around for a long time. So one thing here is cotton, this is from a plant. We can also get fibers from a sheep to make wool and we can weave these fibers together that we get from this plant or this animal and make cloth or padding of some sort, and that serves the squishing purpose, it increases the time and leather over here is another material that you'll see used in old football pads and that actually partially fills this squishing requirement. But it also helps, because it's a tough material helps spread out the force over a larger area. So that's the animal and plant type of materials and that's kind of the oldest class of materials that we've been able to use as humans. So the next kind of material that we got good at using as humans is metals, so what I have here is a picture of iron ore and it really just looks like a rock and that's because it is a rock. But it's a rock that has iron in it and there's a bunch of other stuff in it too. But there's this good metal material inside of that, so I'm gonna write that down ore. That's actually where we get most, maybe all of our metal is from some form of ore that we dig out of the ground, and then through a process called smelting. I'll just write that down as well, smelting, we get the pure form of an iron metal and then from this we're able to mold it into different shapes maybe make buckles and things like that. Buckles and buttons that are on football pads but we can go one step further, we can also mix this iron metal and other kinds of metal together and maybe even materials that aren't metal. Mix them together and create more alloys, so we can also create alloys, and an alloy, I'm throwing a lot of words out here but an alloy is just a mixture of a metal with another metal or another material. To try to give it new properties, and one famous example of an ally is steel, and the reason steel is so famous is because it's actually a very strong and light kind of metal and it allows us to really do a lot of things, we can make taller and taller buildings because steel is so strong. While also being light, and it's also something that you see in a lot of other applications. So this for example, using steel we can make the buckles and little other connecting parts of these football pads stronger and also lighter. The third type of material I want to talk about is called a polymer, so this might be a new word. But there are some kinds of polymer that you're probably already familiar with, one of those is plastic. There are lots of kinds of plastic, but plastic is one kind of polymer. Rubber is another kind of polymer, and polymers are actually the things that are used the most in something like a football pad because you can make so many different kinds of materials with so many different sorts of properties by mixing together different sorts of polymers. So here you can see, here are some football pads and on the surface here all of this is a kind of hard plastic that we've been able to mold and make really light and hard. So that it's both somewhat easy to make these pads and they're also hard enough where they do a really good job of spreading out the force, and these over here are Nerf darts, and Nerf darts are known as being very squishy, and the reason they're squishy is they're made of a polymer, and when the darts are being made they actually fill it up with gas so there are all these little bubbles in it. But it's still able to stay together and just be this really squishy material. And something kind of like that can be put into something like football pads so it can also serve this squishing and increasing time purpose when you're building football pads, so you might be thinking, well what exactly is a polymer, and where does it come from? Well a polymer is basically, it's actually a lot like the fibers you'd find in cotton or wool or something you might make cloth out of. But the fibers are very very small and if you've heard of atoms they're only a few atoms thick. So if I were to zoom way in, on this Nerf dart I might see a bunch of little interlocking threads, so maybe this thread looks like this and there's another thread next to it, and then there's another thread that actually crosses over it, and it wouldn't be in this nice weave pattern so maybe there's another thread that's all curled up in it and it's all tangling. So anytime you see a plastic or a rubber thing or something that's foam what's going on inside of it is that there's this big tangled mess of little strings, inside of it and we can use chemistry to make different types of these little strings. So they stick together different amounts, or weave in different ways and that's what gives us these different properties like really hard plastic or really soft foamy polymer or rubber in a tire or something like that. So that's what a polymer is, and where it comes from, really depends on the kind of polymer. Some of the sources are actually from a plant. So there's actually a tree called the rubber tree that gives us the raw material to start making rubber and we can do things, we can use chemistry to change that into different sorts of materials, and another source of it actually is oil that comes out of the ground the same oil that we use to make gasoline that goes in cars, can actually be used to create polymers that go into all kinds of other things. There are lots of sources of polymers, but they do come from somewhere. They always come from somewhere and then we use chemistry in some way to try different things out and see what we get and then sometimes they're useful for different purposes when you're designing either, a football pad or it could be a building or a toy or a computer or anything. So hopefully it was a little bit interesting to see how we can use different sorts of materials to create and even improve the design of different things and in particular, football pads.