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Prince Rupert's Drop Science · Acedra
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Prince Rupert's Drop Science
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0:00
hey it's me Destin welcome back to smarter every day today we're gonna do awesome science with orbits 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 it's never been done on the Internet okay we are here inside the shop with Cal Cal owns the place can you show them how to make a Prince Rupert's drop so after it cools down this is what you're left with kind
0:44
of 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 okay ready didn't go okay I think Cal is kind of a pansy so I think you can break it so we're gonna try again only this time I'm gonna make you hit it really hard and I'm gonna record it with high speed that work thank you very good all right let's do it the challenge is on yeah [Music] so do you think you actually broke it I
1:15
don't think you did you think you broke it look at a high speed [Music] okay so the drop broke but technically it wasn't the hammer that broken if you look closer than my 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 ball 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
1:54
and I'll show you more okay we're gonna just run an obscene framerate here we have this phantom V 1610 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 going to use this mirror over here to run about 3,000 frames per second so we can get a wide shot to see the whole event as well [Music] okay now we understand what a Prince
2:57
Rupert's drop does but at this point we don't quite understand why it does it let's take a closer look okay this is called a polariscope and basically what it is is a filtered piece of glass that's polarized now 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
3:24
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'll use red to represent molten glass and because the thermal expansion coefficient is 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
3:46
in on itself think of a Prince Rupert's drop is a bunch of little infinitesimal pieces of glass with each piece trying to interact with the pieces around it when the molten glass is first stripped 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 heats transferred to the water that glass on the inside slowly begins to cool down
4:08
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 kinda like how an arch compresses and gets stronger when you put your weight on it only this is in all directions now because the cooling glass can't move that outside layer it begins to pull against itself causing it to be an extremely high tension it then hardens in this state of
4:30
tension and there you have it a Prince Rupert's drop the outside is an extremely high compressive stress and the inside is an 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 least this wave of energy is what we call a failure front you can directly
4:53
measure the velocity of that failure front as long as you have a camera fast enough let's give the shot at 130,000 frames per second [Music] so a big thanks to Cal from Orbitz 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 website click the cat to subscribe with the helmet just said you've never caught the cat on fire ever never not even once these things are named for a guy named Prince Rupert
6:03
imagine that who lived in Bavaria back in the 1600s here 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 no upload blowed up
6:37
[Music]
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