Hello there, I’m Gav. I’m Dan. We’re the Slow Mo Guys. This should be a nice simple video. How fast does glass crack? I actually don’t know but we did that one video with the Pyrex jug where we saw it Yeah, but it was actually quite difficult to figure out the speed because the, the crack was going through a curved Pyrex jug handle. It was about this big. It’s almost like we need a really long piece of glass with foot markers on it. Where could we, uh, get one of those, do you think? Oh! Oh, here’s one. Look at this. I wondered what this was doing here. So in theory if we break this at one end the crack should rush through it I’m gonna put foot lines on it and we’ll be able to determine the exact speed of a glass break What I’ve done here with our 7-foot piece of glass is I’ve spray-painted exactly a foot along the glass Now a foot’s gonna start at, from the cameras point of view the left-hand side of the blue So this edge is gonna be exactly a foot from here. And this one’s gonna be exactly a foot from here, etc So you should be able to calculate the exact speed For glass as we know we need very high speeds. The Phantom Flex4K only does a thousand frames a second. Not worth it. Might see–it’d be couple of frames, maybe, if that. We’ve got the “Twenty Five Twelve” here today. We usually use the “Twenty Five Eleven” This is the next revision Has a different CineMag and a much bigger internal memory. But other than that, it’s the same camera So we’ll start at 28,500 frames a second. A bit nerve-racking, this. Oh, yeah, you’re telling me! Right. You stand there. A bit of foam I see you’ve got there for protection. Yeah, you’ve gotta protect the glass–otherwise it’ll smash before we’re ready. *gasp* Cool. So I’ll hold it here. Okay, you got it? I think so. I’m gonna bug in a ton of shutter here 45 degrees. Oh that’s noise. You never do that. Why do you know in it? Let me just grip this with this and see if I can smash the glass with just a pair of pliers, babe. Go for it That works not really what Oh just vanished God I didn’t expect to be able to do that and then he just went oh You really framed up on the edges aren’t you yep three two one step oh Cool that’s really no I’m surprised you can even see that much with the 28,000. Yeah, it’s because it’s so big This is our starting frame rate. We plan on going much faster. I also like the fact that if I speed up a bit it’s like irrelevant of gravity it splits up and down at the same time because I guess the pressure being released just goes with It also shot forwards and at me once it when you crack it it sort of explodes Yeah, that’s why it makes that like sort of sound or it pops because it like has the pressure built up I guess I did this with pain instead of tape. Oh Yeah, yeah, you could see it separating. You can actually kind of see where everything was even in the air It stays jagged directly in line underneath each other Faster oh, yeah so the way you can increase the framerate on the phantom cameras is you just lower the resolution and As you may have noticed the top on the bottom of the frame here a complete Garbage nor a waste. So what I can do is keep the width the same but lower the vertical resolution So maybe something like that and that way we’re keeping all of the useful area But it will give us the chance to go to Yep, 63 get some a darker. Probably not much sure to compensate Should be So this time I’ll get some different colors in the go Yeah, I’m gonna start by spraying each foot marker with a different color painting with den. Yeh I’m just gonna get on the table here are in a rush. They That’s read done I like that you’re doing this across two tables so you rank both at once I won’t Enjoy that Lovely so the right-hand side of these or your left will be a foot long. This is pretty satisfying Slop it in there When you get a chance, okay, let me try and fill the frame with this mad lad go for it my level Okay, Dan, it’s time for some maths Versus I’m gonna get up the true Time of this crack and we’ll measure how long in seconds it took each foot to break There’s a slight discrepancy between each one just because of which side of the foot mark of the crack landed on that particular frame But don’t worry will a ver each term out more Matt Giving us average time of point zero zero two seconds per foot which is forty seven hundred and fifty eight feet per second and for the international audiences, that’s 1,450 M years per second 3262 miles per hour 5250 km/h or mac 4.20 You know, my mind is blown. I don’t think that there’s anything that’s like physical but that’s quick What’s physical that that’s quickly? What goes Mac 4.2 apart from spaceship? It’s almost it’s weird how like none of it overtakes anything else like, okay so it starts as round right? See that it’s not rounded. Yeah, so the middle of the glass is actually ahead of the sides But it catches up and then it’s all just going in a line. Do you know I think Right, that is not I don’t expect to see there I think it what it looks like is if this was actually a circle like if it was like a 14 Foot circle. Yeah, and you smashed the middle it would all go out in a circle But we’re just seeing like a section of that. So if you imagine that It starts off as a small circle it gets bigger and bigger. It doesn’t it’s not actually flat when he gets the end It’s still slightly curved. So I’m just imagining a circle getting bigger. Therefore. The edge is getting flatter. Yeah, exactly bloody Mental now can’t want to do it a big circle fresh out of 14-foot glass circles, unfortunately good church window alright, so that was 78,000 multi-coloured. Yeah, I think it’s time to get carried away This bad boys the capable of some serious, let’s Lincoln. Let’s let it stretch this legs Thank you every spin Will reduce the horizontal width as well Lose some more on the vehicle maybe go To five six by Ninety six, that’s small enough giving us a frame rate over four hundred and eighty one and a half Thousand frames a second because we’re now so cropped in I’m only gonna be seeing two colors. So there’s no point painting the rest waste the paint waste a paint Glass is cool Oh Ridiculous, how much can you see bloody stupid? This is She’s that one pot? Let’s look at this ridiculousness It just looks like a software wipe it’s just like we took two fixes then just wiped across it just instantly turns it to like lizard skin just turns into like Scales this cameras. So cool just records all that like that happened and it recorded it at that. Yeah this camera saw everything final aftermath Another pretty aftermath that is not bad. It sounds like snow – listen Don’t like snow but what’s cool is the fact that cuz obviously we did it all in in color order. It’s all stayed there and Look, this is all This looks like it’s an intact piece of glass but it’s actually oh, yeah, at least smash it’s gone It’s just held together by there. Yeah, which is why it was good that lab We didn’t record the the paint side who recorded the front side so you can see the cracking around the color Well, we learned the speed that a crack propagates through laminated sheet of glass Yeah, they’ve temp in action. You couldn’t tell with the the little video we did before but that really demonstrated It was so fast and and the way it starts as a circle and then basically gets Bigger for in a circle, even though it’s a flat rectangular piece of glass. I was really impressed by that I didn’t I didn’t expect to see that I guess you’d never know it unless you see a long piece of glass slow motion in my head You were gonna crack it and it would just come across as a straight ball the whole way of outside Oh, of course. It’s gonna crack from that point and then the fact that it evened out was very cool to me Yeah, it was awesome Hopefully you enjoyed that video bung it alike. If you did, there’s a dislike button – that’s always fun. Subscribe to the slow Mo guys and we’ve got a second channel any closing thoughts Daniel gets a bear get a broomis will get a get a broom Yep for this got this grass Glass grass grow I met grass that time. Okay. Yeah because I’m gonna sweep up the glass from the grass Yeah

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Dennis Veasley

4 thoughts on “How fast does glass crack? – The Slow Mo Guys”

  1. Hello everyone. I recommend you watch this one full screen or on a computer so you can see the cracks more clearly. They look bloody tiny on a phone screen! – Gav

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