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Mystery of Prince Rupert's Drop at 130,000 fps - Smarter Every Day 86

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transcript:
Hey it's me Destin. Welcome back to Smarter Every Day. Today we're gonna do awesome science with Orbix Hot Glass here at Lookout Mountain Alabama. Goggle up. Science is about to happen. We're gonna use a high speed camera and learn about Prince Rupert's Drop. [whispers] It's never been done on the internet. You're gonna learn something. Let's go. OK we are here inside the shop with Cal. Cal owns the place. Can you show me how to make a Prince Rupert's Drop? (Cal) Sure. I'm gonna gather some glass, drop it in a bucket of cold water. [sizzling sound] (Destin) So after it cools down, this is what you're left with. It kinda looks like a tadpole, but it has some really interesting mechanical properties. We can actually hit this thing with a hammer and it won't break. OK I'm ready. [bang] Didn't go. OK I think Cal is kind of a pansy so I.. You think you can break it? [laugh] So we're gonna try again only this time I'm gonna make him hit it really hard and I'm gonna record it with high speed. Does that work? Think you can break it? Alright. Let's do it. The challenge is on. (Cal) Just hit it? - Yep. [bang] [shattering] [laughs] So do you think you actually broke it? I don't think you did. You think you broke it? - I know I broke it. [laugh] - Let's look at the high speed. [music] OK so the drop broke, but technically it wasn't the hammer that broke it. If you look close in the high speed you can see that it's the wiggling of the tail that makes it go. This is the mystery of the Prince Rupert's Drop. You can try as hard as you can to break the bulb, but you can't. But, if you even nick the tail, the entire thing will explode. Not shatter, but actually explode. Let's go outside and I'll show you more. OK we're gonna just run an obscene frame rate here. We have this Phantom V1610. So, glass breaking occurs so fast that you have to have like hundreds of thousands of frames per second, so we're gonna have a lower resolution and we have to have a lot of light as well. We're also gonna use this Miro over here to run about 3000 frames per second so we can get a wide shot to see the whole event. as well. 3..2..1.. go. [shatter] [Awesome Music by Gordon McGladdery} OK now we understand what a Prince Rupert Drop does, but at this point we don't quite understand why it does it. Let's take a closer look. OK this is called a polariscope and basically what it is is it's a filtered piece of glass that's polarized. I have another filter here. You can see if I turn it, then I can block out the light. Now if I put this on the camera that you're looking through here, and then I put the Prince Rupert's Drop in between the two pieces of glass, you should be able to see the internal stresses built up inside the Prince Rupert's Drop. So to understand how these stresses got here, let's use the color grey to represent nice and strong solid glass. We use red to represent molten glass and because of the thermal expansion coefficient it's safe to assume that the higher the temperature the larger this glass wants to be. Blue represents glass that's cooling off, or transitioning between the two states. Because of that same thermal expansion coefficient this glass is shrinking and basically pulling in on itself. Think of a Prince Rupert's Drop as a bunch of little infantessimal pieces of glass with each piece trying to interact with the pieces around it. When the molten glass is first dripped into the water, the outside layer touches the water and immediately solidifies. This locks in that outside shape of the drop. The inside of the drop however is still a hot expanded liquid. As heat's transferred to the water that glass on the inside slowly begins to cool down, and pulls in against that outside layer. The problem is that because it's already locked in as a round solid, it only compresses tighter against itself. This actually makes it stronger. Kind of like how an arch compresses and gets stronger when you put your weight on it only this is in all directions. And because the cooling glass can't move that outside layer it begins to pull against itself, causing it to be in extremely high tension. It then hardens in this state of tension and there you have it, a Prince Rupert's Drop. The outside is in extremely high compressive stress and the inside is in extremely high tensile stress. If one link in this tension chain is ever cut, it breaks on down the line, feeding off of its own stored up energy just like a chemical explosive does. The difference here is that instead of releasing chemical potential energy mechanical strain energy is released. This wave of energy is what we call a failure front. You can directly measure the velocity of that failure front as long as you have a camera fast enough. Let's give it a shot at 130,000 frames per second. 3..2..1..go. Got it? [music] So a big thanks to Cal from Orbix Hot Glass. If you found this interesting and you want to support him by buying stuff go click on the link, wherever I put it, and go check out his web site. Click the cat to subscribe. With the helmet. [laugh] It's a sad looking cat. You've never caught the cat on fire, ever? - Never. - Not even once? - Never. - These things are named for a guy named Prince Rupert, imagine that, who lived in Bavaria back in the 1600s. Here, here. [shins banging on concrete laughter through pain] He brought these over as a gift to King Charles II in England who gave them to his Royal Society to try to figure out. Yep ready. [clang] Holy smokes! - Aah the tension's killing me. [shatter] -(Destin in background) NO DON'T BLOW UP! - You know it blow.. blowed up? - Yep, it blowed up. - It BLOWED UP Y'ALL! [laugh] Captioning in different languages welcome. Please contact Destin if you can help. [ Captions by Andrew Jackson ] captionsbyandrew.wordpress.com

auto_transcript:
it's a test of time it's mari day-to-day really awesome sight with orbit last year lookout mountain alabama double up science is about to happen readies a high speed camera and about prince rupert drop it's never acts okay we're inside the cell with cal calories the place commission now to make a pressure for struck homeowner the actor calls them this is what your work edvel that's really the mechanical problems would actually get this thing with a hammer him over it forgetting calstart keynesian so i'm they deliver it historians write you know it is time to make it really hard time of our allies was near the town of oh do so do you think you actually predict how the kids be diverted driven out of hand that i'd be and is that the driver of but candidly it wasn't for him in the brain people's was expediency that is the way we know the details and makes him this mystery in the grass roots medium-sized working here republic but he can't behaving the handle entire being launched word not shadow actually spoiled let's go outside apparently just reading that scene frame rate here we have this then and the sixteen ten so glass breaking occurs so fast that you have to have like hundreds of thousands of frames per second so we have a lower resolution forget that a lot of light as well for us attorneys this mayor of ricky rector about three thousand french for second certain the wide shots the devils and as well now we understand what the prince rupert dot at this point we don't quite understand why it doesn't let's take a closer look rediscover polaris co and baseball is a safe filtered peaceable assets polarized i had another filter here you can see if i can it then i can walk out about that this on the camera that there looking through here let's its he should be able to see the internal stresses built-up inside the interpret sort of understand how he stresses got careless use the color greater represent nice and strong soften collapse wees red represent multiple ass because of the most pension coefficient is safe to assume that the higher the temperature toolbar judas class wants to be blue represents class at school and offer transition between the two states because that same thermal expansion coefficient this class is shrinking in basically pulling in on itself because the prince rupert struck his acquittal infinitesimal he's glass with each piece trying to interact with the pieces around it when the molten glass is first ripped into the water the outside lawyer touches the water in immediately solidifies this locks in that outside shape of the truck instead of the drug however still extensively essence transferred to the water placement inside slowly begins to cool down and pulls in against that outside layer the problem is that because it's already locked in as around solid it only compresses tighter against self the sex that makes it stronger college counterparts compresses and each army persuade own it only this is an alterations because the cool glass can't move that outside layer it begins to pull against itself causing it to be an extremely high tension it it hardens in the state of tension and there you have it prince rupert strap yes i was an extremely high compressive stress any insight is an extremely high tensile stress if one link in the stitching chain is ever cut it breaks on down the line feeding off of its own stored up in her g just like a chemical explosive does the difference here is that instead of releasing chemical potential energy mechanical strain the energy is released this way that it is what we call the feel your from speaking directly measured the blasted that their product as long as you have a camera fast enough let's give a shout at a higher in thirty thousand frames per second the so the next decade offer orbit last because if they didn't want to see for about bites that people don't know it where i put it and uh... digitalis website quickly can subscribe the helmet toolset daycare never cocktail fire that he wants on these things are named for a guy named please revert imagine that you live in the bay area back in the sixteen hundreds have been he brought these over as a get the king charles the second england gave into his royal society try to figure out always upset really no good dash produce