How fast does glass crack? – The Slow Mo Guys

How fast does glass crack? – The Slow Mo Guys

Gav and Dan use some absolutely insane frame rates to learn how fast 5 millimetre tempered glass cracks. 3 pieces of glass were harmed in the making of this video.
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Filmed at 28,500, 78,000 and 481,000fps on the Phantom V2512
How fast does glass crack? – The Slow Mo Guys

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64 Responses

  1. The Slow Mo Guys says:

    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

  2. Michael H. says:

    Who else didn’t notice the glass pane Dan was holding until they mentioned it at 0:24?

  3. GaeafBlaidde says:

    Love the analysis in this video. Dans description of the curvature of the fractures by considering the pane as a section of larger circle is spot on. Not only is it mathematically/physically correct they, explain it in such a way most people can understand it

  4. SmarterEveryDay says:

    Excellent analysis on the failure front.

    • Ian Cook says:

      <3 u Destin

    • TheAgentTexas says:

      +luis granados Speed of sound through glass. That’s exactly what I was thinking.

    • Dalton Worsnup says:

      I would be interested in seeing this done with glass in a frame to compare the failure fronts. My thinking is that the glass broke in such a uniform manner because there was nothing to reflect the propagating energy. If there were a frame however, the glass couldn’t expand freely as it broke which would produce additional stresses. This leads me to hypothesize that the failure front would reflect off the frame like a wave.

    • Dennis Woycheshen says:

      +Dalton Worsnup just like a pool… 😀

    • Isaac Alonzo says:

      Was looking for this comment, the smarter everyday analysis should be coming soon. Amirite?

  5. Tyler says:

    you guys need to get with destin again and film a prince rupert’s drop in super slow mo

  6. Vincent Horvath says:

    Pretty sure you could do it mathematically

    The speed at which waves travel through a material is the same as the speed of sound in that material. The speed of sound in a material can be estimated by knowing that material’s density and bulk modulus. The formula is


    where c is speed of propagation, K is the modulus of elasticity, and p is the material’s density. One may also use a materials shear modulus in place of the modulus of elasticity. The type of breaking that occurs likely dictates how fast the break will propagate and hence, which modulus should be used in the above formula.

    If one applies the above formula to glass, (taking the shear modulus of 26.2 GPa and a density of 2.5*103 kg/m3) we get a speed of sound of ~3200 m/s.

    ( )

  7. Newtronwest says:

    I think Dan might be right on his hypothesis of the glass break propagating outwards in a circular manner. Get a custom sheet of round glass 3 or 4ft in diameter and paint it in a pinwheel motif?

  8. DepressoExpresso says:

    These guys have 11 million subs and they’re still shooting in the same suburban backyard you gotta give them props for that

    • Andrew Howard says:

      +Tommy Dee Oh yeah I’m more of a roosterteeth fan than the slomoguys so I could be wrong but I’m pretty sure most of their videos have been filmed in the US other than very very early ones because the whole reason Gavin started this channel was so that he could get a visa to move here. Could be wrong though!

    • Micah Philson says:

      Well, originally it was one of their houses in England, but ever since Gav moved to Texas to be part of Rooster Teeth, they’ve been filming in the backyard of his house there.

    • emojo1990 says:

      +drake6143 can buy half of detroit for the price of a phantom

    • DepressoExpresso says:

      +The Slow Mo Guys You Absolute Mad Lads

    • Cynthia Flores says:

      Micah Philson yes I think they use to film a lot in Dan’s (grandpa’s) garden

  9. JodieWho says:

    I prefer them not on the super slow show

  10. Edigoron says:

    6:09 Try explaining that to a flat earther… he wont understand

  11. loco Penguin says:

    Who Else Didn’t See the Glass, Be Honest…

    • KHRN Star says:

      loco Penguin
      I saw it way before…because of his Hand’s position it caught my eye. Then is instantly noticed it’s a block of glass…also the edges were like a long string when was visible clearly.

    • CreativeArtStudios says:

      I didn’t see it at the beginning

  12. zerosonico says:

    So we can all agree you guys now have to make a giant round glass video.

  13. Cesare Vesdani says:

    You guys haven’t made a video for a long time. I have another glass video idea for you. Please make another glass video. Please take a new glass sheet, wash it with hot water, then rinse it with hot water and let it dry naturally without touching it. Then, get a jumper and rub it against the glass to make it squeaky. That is an experiment that I have found out myself. Please show us how it works in deeper details. Thanks.

  14. Ravven14 says:

    Who remembers the longest 5 seconds on youtube?

  15. Zonies Coasters says:

    you should go record your neighbor on the drums in slo mo

  16. Jetpacker Josh says:

    Still better than YouTube Rewind

  17. Kevin Luo says:

    The paint might have made the glass crack slower.

  18. SpookyWalrus says:

    The American X-15 was a hypersonic rocket-type aircraft. The thing reached up to 4532MPH or Mach 6+! Although the thing was pretty much a manned rocket, it’s still pretty cool.

  19. Kaz says:

    After 3 years Dans lab coat is still ripped and covered in paintball stains..

  20. Nathan Schmick says:

    I want a video showing how fast two liquid droplets will join surface tension and become one drop. You could do them two different colors.

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