How Strong Velcro Really Is?

[00:00:00]Can you pull a 100,000 ton cargo ship with Velcro? Well, yes. The question isn't can you, but rather how much of it would it even take? You see, Velcro is kind of amazing because it can generate a huge amount of force with a very small surface area. But a cargo ship is one of the biggest and heaviest moving objects on the planet.

[00:00:22]So, can you actually move the ship with Velcro alone? And is there even enough Velcro on the planet to do so?

[00:00:29]Let's put things into perspective.

[00:00:31]Here's a banana. To pull an average size banana, you need a piece of Velcro with a similar area as the one at the top of a typical pencil eraser. So, roughly a rectangle of 6 by 6 mm.

[00:00:44]The difference in size between both objects is quite substantial. The banana is 1,800 times larger than the amount of Velcro we need to actually move it. But how does it even work? If you put a piece of Velcro under a microscope, the engineering is actually quite simple.

[00:01:00]One of the slices is filled with hundreds of tiny stiff plastic hooks, while the other holds a smaller amount of soft nylon loops. When we push them together, by sheer force of probability, the hooks get into the loops like 100,000 tiny fishing lines. And that's the secret to its insane strength. When you try to pull those two pieces straight apart, you need to make enough force to separate [music] all the hooks.

[00:01:24]Every single hook is resisting you at the exact same time. Engineers call this tensile strength and it's surprisingly efficient. But if it's so strong, how can you actually separate them?

[00:01:36]It all depends on the direction you're pulling from. The strength of Velcro comes directly from the sheer number of hooks we're trying to pull apart, which depends on the direction of the applied force. The strength ratio between peeling, pulling straight out, and sliding it parallel is roughly 1 to 5 to 7. Take a piece of Velcro exactly the size of a CD case. If you try to separate it by peeling a corner, it falls at just 50 Newtons. Peeling is the weakness of Velcro, since you'll be fighting only one row of hooks at a [music] time.

[00:02:06]But pull that exact same patch straight out, and the strength skyrockets to over 1,200 Newtons. Every hook is suddenly engaged. The catch is that you're pulling the hooks against their open ends, so they flex and pop out. It's strong, but it's not the optimal way to lift heavy weight.

[00:02:24]For that, you'll have to make the Velcro work under shear load. When you pull the pieces parallel to each other, the hooks dig their heels in across the entire surface.

[00:02:34]To break that same CD-sized patch in pure shear, you'd have to pull with over 1,700 Newtons of force. That means this single piece of Velcro, no bigger than a CD, won't just hold a 90 kilo human off the ground, it will easily hold two of them there all day.

[00:02:52]Now, take a look at this truck. A typical commercial truck weighs around 15 tons, or 33,000 lbs.

[00:02:59]But here's the thing, to pull it, we don't need to lift those 15,000 kilos off the ground. We just need to overcome its static friction to get the wheels rolling.

[00:03:09]For this, the standard nylon Velcro we all know and love won't cut it, because regular Velcro relies on soft, flexible loops. It's not meant to hold thousands of kilos, and it would just [music] rip them to shreds. So, we need an upgrade.

[00:03:23]We need industrial Velcro.

[00:03:26]Heavy-duty industrial Velcro uses thick, rigid plastic mushroom heads on both sides. When you push them together, they physically snap and lock into place.

[00:03:35]Because both sides are rigid plastic, this geometry is roughly three to five times stronger than standard Velcro in a pure shear load. It doesn't stretch, and it doesn't fray.

[00:03:47]So, now that we've upgraded our gear, how much do we actually need to get 15,000 kilos of steel rolling? Although it may sound surprising, the math is clear. You only need a piece of industrial Velcro roughly the size of a standard skateboard deck. A single piece of plastic the size of a skateboard pulling a massive commercial truck down the highway. Not bad, but a truck is nothing compared to our final goal, the huge cargo ship.

[00:04:16]But before we get there, how did we even come up with Velcro in the first place?

[00:04:21]You might think a mechanism this powerful was designed in some top secret military lab, but it wasn't. It was discovered by accident by a guy walking his dog. Back in the 1940s, a Swiss engineer named George de Mestral took his dog for a hike in the Alps. When they came back, both his pants and the dog's fur were absolutely covered in these annoying little plant seeds called burdock burs. Most people just pull them off and throw them away, but he didn't.

[00:04:47]He wanted to know exactly why they were sticking so stubbornly. So, he put one under a microscope, and what he saw was nature's own version of what we just talked about. The seed was covered in hundreds of microscopic stiff hooks, and they were perfectly designed to catch onto the soft tangled loops of animal fur, or in this case, >> [music] >> his wool pants. Nature had already solved the mechanical problem. He just had to figure out how to manufacture it.

[00:05:14]It took him over 10 years of trial and error to replicate that natural design using nylon. He created one strip to mimic the stiff hooks of the bur, and another to mimic the soft loops of the fabric. And so, he combined the French words for velvet, velour, and hook, crochet, giving birth to the brand Velcro. Now, can you actually move a full-on cargo ship using nothing but Velcro? A fully loaded cargo ship weighs around [music] 200,000 tons, which is over 13,000 times heavier than our truck. So, how on earth do we pull it?

[00:05:49]Well, it depends on the context. If we try to [music] pull it in the ocean, that's basically a giant cheat code.

[00:05:55]Because of buoyancy, the water is actually what supports the full weight of the massive ship. So, we don't have to lift 200,000 tons. We only have to overcome the hydrodynamic drag of the water pushing against the hull. And to do that, the math again shows us a surprisingly small number. We only need a patch of industrial Velcro roughly the size of two average parking spots.

[00:06:17]One of the largest, heaviest man-made structures on the planet dragged across the ocean by a piece of plastic the size of two parking spots.

[00:06:26]But, what if we took the water away?

[00:06:28]What if we wanted to pick the ship straight up out of the ocean and hang it in the air?

[00:06:34]Now, we are the ones actually lifting the full weight of the ship. So, we need to fight gravity. And for that, two parking spaces won't even come close. To hold that much dead weight in the air, we need a solid sheet of industrial Velcro the size of four American football fields. Which brings us back to the question we asked at the very beginning, is there actually enough Velcro on Earth to pull this off? Yes.

[00:06:56]Easily. Since George invented it, factories have been pumping out millions of [music] square meters of hook and loop fasteners every single year.

[00:07:04]If you gathered up every shoe, backpack, industrial roll, [music] and landfill scrap on the planet, you would have roughly 3 billion square meters of Velcro.

[00:07:13]That is a single continuous sheet of plastic hooks large enough to completely cover the entire state of Rhode Island.

[00:07:21]That much Velcro could hold up to 30 billion tons. To put that into perspective, 30 billion tons is enough to hold 150,000 fully loaded cargo ships.

[00:07:32]That would mean taking the entire global commercial shipping fleet and hanging them without any problem.

[00:07:39]But, we can push this even further. What if we took that Rhode Island sized [music] sheet of Velcro and tried to pull the entire Earth?

[00:07:47]It definitely sounds ridiculous, but physics doesn't care about ridiculousness. It only cares about math.

[00:07:54]The Earth has a mass of almost 6 ronagrams. That is a six [music] followed by 27 zeros.

[00:08:01]That sounds like a lot. How much Velcro would it actually take to hold it?

[00:08:06]Well, to hold the Earth, Rhode Island won't cut it. Actually, not even a Velcro the size of the entire United States would cut it. Not even one the size of all the continents put together.

[00:08:18]The math says you'd need a sheet of Velcro 1 million times larger than the entire surface area of the Earth itself.

[00:08:25]Sometimes, even if the math works, things are physically impossible.