Downhill Rotation Race – Smarter Every Day 13

Mobile users: VOTE ICE: VOTE WATER:

This problem is more difficult than it appears. One one side you have rotational inertia to deal with. On the other you’ve got fluid shear. I bet you can’t get this right. If you don’t, please subscribe to help fight the epidemic of everyday ignorance.

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42 Replies to “Downhill Rotation Race – Smarter Every Day 13”

  1. Muonium says:

    I was genuinely surprised by this experiment's result. So much so that I DID subscribe. Incidentally, very intelligent scientifically minded people who retain a high degree of religiosity intrigue me. I just found your reddit comments and am currently reading through them with considerable interest. May I ask, do you have any experience with the skeptic community (eg. the SGU, James Randi,etc)? I think it may be a gentler more rational introduction to freethought than going the r/atheism/ route.

  2. kevjay777 says:

    I didn't click at first because I thought the test conditions were too flawed and it could go either way. So I was right. And in the second video where you said everyone was wrong, using that premise everyone could just as well be correct thus, no one would have to subscribe. I'm going to subscribe anyway because you are a cool dude and you have a sharp brain.

  3. JDLupus says:

    I'm sorry, destin, but it took me a good fifteen minutes to finish the video. I was pressing 2 instead. The way you fell back after being hit was PRICELESS!

  4. Josh Ferman says:

    I'm guessing it's liquid but idk cause I'm on iPod, can someone please tell me

  5. amliljay says:

    0:20 alli can say

  6. Jeroen Blonk says:

    I think ice but im on iphone so i dont know

  7. Ian Self says:

    That was a hard hit man!

  8. Count says:

    @destinws2 , i was already a subscriber to you but then my youtube account got deleted by a mean friend, so now i get to subscribe again! yay!!

  9. @TheCountMomo
    Time for new friends!

  10. Tolyzor says:

    Clicked liquid because I figured they would have a similar amount of weight force accelerating them, but the liquid one effectively has less rotational inertia to overcome.

    I highly doubt even a fluid dynamics professor could have guessed the flow would go turbulent and cause the result you got, without sitting down and doing some calcs first!

  11. jaborla says:

    00:19 Now he´s not smart anymore

  12. wow that dangerous with those pipes

  13. That should make people sub haha.

  14. What parents @ students need to know about study skills.When you discover how your mind works ,You will become a lot smarter -more creative @ faster learner in every subject.You can get all the information free of charge at [mental training & improving life skills] onutube

  15. SanUM says:

    Ice Ice Baby… 🙂

  16. BMaui1 says:

    Mater accelerates at 9.8 m/s/s regardless of the type and weight ,and cense they have the same air resistants they will tie

  17. BMaui1 says:

    I subscribed anyways

  18. I like your channel but this Hardy boys adventure novel shit sucks, Just show us the damn results instead of stringing us along. I'm about to unsub! Not that you care, but damn that is annoying!!

  19. There is an excellent guy, veritasium, and he says this is the best way to learn. He made his PhD on it. I would believe him on this.

  20. First, the bottles are rolling, not falling, so you have to take into account angular momentum, not only mass. Second, the liquid in the bottle spins slower than the bottle itself because it has small friction against the walls of the bottle.

  21. who the hell threw that ball at you?

  22. You cant win.
    The 2 links is the same
    Check for yourself

    Shame on you Destin

  23. Jason M. says:

    Hey Dustin, I love your vids. I watch one everyday. I dont seem to really be wrapping my head around this one though. I'm quite sure this is very complicated. (to complicated to be wholesomely explained in two min) but this vid seems a little more over my head than usual.

  24. Robsrosin says:

    Thumbs up for the ball to the face!

  25. YeyeTV says:

    hahah i got kinda shocked with the ball to the face hahaha

  26. lryanle says:

    I thought it was a trick question and both was going to win, does that mean I don't subscribe? Nah, already did xD

  27. Maayu says:

    You tricked us.. You didn't tell us that bottle with water if full.. I thought that it has air in it.. It's cool to watch your olders videos and compare them to those new.

  28. 3mily Jad3 says:

    Which onnnne was it?????

  29. There's rootbeer out of my nose, on my carpet keyboard mouse and TV from spitting it out laughing abruptly at the dodgeball….

  30. Nathaniel B. says:

    It seems like he changed his annotations on his older videos – it didn't give me the option to choose either.

  31. Dean Philips says:

    Neither one is faster, the video freezes right where you let go (O:52).

  32. Guys if you want the answer check the description.

  33. KG7TUO says:

    Well it's 9 years ago and I didn't read all the comments but I also haven't found what i offered as the answer.

    I vote for the ICE for two reasons. One there are no losses due to the friction of the moving liquid and TWO…….water is unique in that it contracts like most materials when cooled but it begins to expand as it gets to the freezing point. This phenomenon accounts for a lot of the erosion of massive rock formations that are exposed to winter freezing. In this situation, even though contained by the plastic bottle, it will cause the bottle to expand slightly. The mass of the water volume will be further from the axle of the bottle with liquid and will this rotate faster and reach the end of the slope faster.

  34. Mary Lagua says:

    I’m sure that ball hurt your face.