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Physics Holds the Key To Performing the Flipping Water Bottle Trick (arstechnica.com)

An anonymous reader shares a report: Think of how ice skaters extend their arms and legs to slow down rotation coming out of jumps or spins. It's the same principle: conservation of angular momentum. Once the bottle is set in motion, its angular momentum remains constant. But shifting how the mass inside (the water) is distributed increases the bottle's rotational inertia (how much force is required to start or keep it moving). This slows down the bottle's rotational speed. Physicists from the University of Twente in the Netherlands decided to analyze the underlying physics [of flipping a half-full bottle of water so it lands upright] more thoroughly in a series of rigorous experiments and develop a theoretical model. For the first version of the experiment, they used a partially filled water bottle. For the second version, they reduced the variables from the large number of water molecules in the bottle to just two tennis balls in a cylindrical container. In both cases, their measurements clearly showed the dramatic decrease of the container's rotational speed, resulting in a nearly vertical descent, so the bottle landed neatly and upright. Tracking the sloshing of the liquid and the changing positions of the tennis balls demonstrated the redistribution of mass, shifting the moment of inertia.

56 comments

  1. Next up on Slashdot by ArchieBunker · · Score: 4, Insightful

    Fidget Spinners: We review 10 the top ten fidget spinners of 2018!

    --
    Only the State obtains its revenue by coercion. - Murray Rothbard
    1. Re:Next up on Slashdot by sconeu · · Score: 2

      Fidget Spinners: We review 10 the top ten fidget spinners of 2018!

      <obligatory>
      Number 7 will surprise you!
      </obligatory>

      --
      General Relativity: Space-time tells matter where to go; Matter tells space-time what shape to be.
    2. Re: Next up on Slashdot by TimMD909 · · Score: 1

      Fidget spinners are about angular momentum too... Don't give them any ideas...

  2. Ummm ... yeah ... by Anonymous Coward · · Score: 4, Insightful

    Physics Holds the Key To Performing the Flipping Water Bottle Trick

    No shit, physics holds the key to pretty much everything. :-P

    1. Re:Ummm ... yeah ... by spire3661 · · Score: 1

      That Newton fellow didnt even invent anything, he just described what was already there. Why is this guy even famous? ;)

      --
      Good-bye
    2. Re:Ummm ... yeah ... by Anonymous Coward · · Score: 0

      That Newton fellow didnt even invent anything, he just described what was already there. Why is this guy even famous? ;)

      Not criticizing the science, but the headline is stupid because it's a truism.

    3. Re:Ummm ... yeah ... by careysub · · Score: 1

      Guns don't kill people! Physics kills people! - Dick Solomon, "Third Rock From the SUn".

      --
      Starships were meant to fly, Hands up and touch the sky - Nicky Minaj
    4. Re:Ummm ... yeah ... by Anonymous Coward · · Score: 0

      It's all junk science, IMHO. Physics can't explain why,
      after you start to spin an uncooked egg, it accelerates
      slightly before finally slowing. Also, why said layer crossed
      the road. These are important issues not addressed by "physics."

      CAP === 'infancy'

    5. Re:Ummm ... yeah ... by slickwillie · · Score: 2

      That Newton fellow didnt even invent anything, he just described what was already there. Why is this guy even famous? ;)

      Because he also invented a tasty cookie with a fig filling.

    6. Re:Ummm ... yeah ... by Anonymous Coward · · Score: 0

      Not magic, you stinking muggle!

    7. Re:Ummm ... yeah ... by sconeu · · Score: 1

      I'm shocked, SHOCKED! To find that physics holds the key to describing physical phenomena.

      --
      General Relativity: Space-time tells matter where to go; Matter tells space-time what shape to be.
    8. Re:Ummm ... yeah ... by Anonymous Coward · · Score: 0

      I thought that was Issac Newman

  3. VIRAL! by Anonymous Coward · · Score: 0

    like an STD!

  4. Flipping water bottle by Anonymous Coward · · Score: 1

    What is this water bottle trick, and why are they so triggered by it?

  5. No shit by Gunnery+Sgt.+Hartman · · Score: 2

    Was this from the "No Shit Department of Things That are Obvious"?

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    [ ]
    1. Re:No shit by scott_evil · · Score: 1

      I hit the comments to write "no shit", but you beat me to it and put it far more eloquently than I could. Well done sir.

  6. Cats and toast by SqueakyMouse · · Score: 1

    But what happens if we attach it upside to a cats back and flip it? Does the cat land on its feet or upside down? What if attach toast with jam on one side? Does the toast still always land jam-side down in accordance with murphy's law?

    1. Re:Cats and toast by Anonymous Coward · · Score: 0

      But what happens if we attach it upside to a cats back and flip it? Does the cat land on its feet or upside down? What if attach toast with jam on one side? Does the toast still always land jam-side down in accordance with murphy's law?

      What if you put jam on the cat?

    2. Re:Cats and toast by Anonymous Coward · · Score: 0

      But what happens if we attach it upside to a cats back and flip it? Does the cat land on its feet or upside down?

      Well, the cat controls it own balance, so it has an edge on the toast ... but it's been postulated the cat and toast will then spin endlessly above the ground in some bizarre cat/toast perpetual motion machine.

      The biggest trick is going to be strapping the toast the cat without getting yourself killed in the process. Do post a video of that for us.

    3. Re:Cats and toast by Anonymous Coward · · Score: 0

      But what happens if we attach it upside to a cats back and flip it? Does the cat land on its feet or upside down? What if attach toast with jam on one side? Does the toast still always land jam-side down in accordance with murphy's law?

      What if you put jam on the cat?

      Eff that.

      I want to see SqueakyMouse try to toast a cat.

    4. Re:Cats and toast by Herve5 · · Score: 1

      Arrgh, and I lost all my mod points yesterday...

      --
      Herve S.
  7. Unnecessary correction by Anonymous Coward · · Score: 0

    Figure skater, not hockey skater.

  8. Physics is the key to physical feats. by Gravis+Zero · · Score: 4, Funny

    You don't say! -_-

    --
    Anons need not reply. Questions end with a question mark.
  9. excellent work, but theres still more to be done. by nimbius · · Score: 1

    Before I, a millenial, can ensure everything gen Z loves is made un-cool, more research must be done. Specifically:
    - Scientific inquiry into the physics of fidget spinners
    - a full computational simulation and kinematic treatise on the fortnight dance
    - finite element analysis and thesis on the nature of the Tide pod.
    - historic carbon dating of Post Malone to determine the potential for the existence of a Pre Malone, or a Present Malone (particle physics as needed)

    --
    Good people go to bed earlier.
  10. Ig Nobel Committee on line 2 by sjbe · · Score: 1

    Physicists from the University of Twente in the Netherlands decided to analyze the underlying physics [of flipping a half-full bottle of water so it lands upright] more thoroughly in a series of rigorous experiments and develop a theoretical model.

    I sense they are gunning for an Ig Nobel Prize with this critical and ground breaking research.

  11. Damn by king+neckbeard · · Score: 1

    I thought a task that involves physical movement through space would be explained by chemistry or biology...

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    This is my signature. There are many like it, but this one is mine.
  12. Obvious pretext by Anonymous Coward · · Score: 0

    Obviously an excuse to invent a new beer game on tax payer's dime.

  13. Wish I had that kind of time... by turp182 · · Score: 1

    And they are getting paid for it I assume.

    If not, cool project.

    If so, just another step towards Idiocracy (with regards to the research topics at the beginning of the movie).

    --
    BlameBillCosby.com
  14. Feh by NoNonAlphaCharsHere · · Score: 4, Funny

    The flipping water bottle trick only works for inertial frames of reference. Get back to me when you work out Special Flipping.

    1. Re:Feh by Anonymous Coward · · Score: 0

      The flipping water bottle trick only works for inertial frames of reference. Get back to me when you work out Special Flipping.

      I can show you some special flipping...

    2. Re: Feh by Anonymous Coward · · Score: 0

      Good joke but you mixed up your relativities. Special applies to inertial frames, and general applies to all.

  15. Glad we got that one squared away by Anonymous Coward · · Score: 0

    Now lets see what Biology says about Planking

  16. Contrary opinion by SuperKendall · · Score: 3, Interesting

    Well all of the Slashdot posters today seem to be gunning for most snide comment.

    Maybe they didn't read the whole summary? Because I for one thought it was pretty cool they reduced the problem down to a canister and two tennis balls to demonstrate the same effect in an easier to understand way.

    People may find this pointless. but you never know when understanding something others consider to be obvious or not worth knowing may be helpful. You never know what kid may get into science because of being fascinated by this reduction.

    I say, good work!

    --
    "There is more worth loving than we have strength to love." - Brian Jay Stanley
    1. Re:Contrary opinion by king+neckbeard · · Score: 3, Insightful

      The snide isn't because there isn't an interesting explanation. The headline is just incredibly stupid, and is thus derided.

      --
      This is my signature. There are many like it, but this one is mine.
    2. Re:Contrary opinion by Anonymous Coward · · Score: 0

      The snide remarks are because anyone who has ever held a water bottle understands the general relationship described here. Anyone who has tossed a bottle has seen it in action. No "physics" are required. This is a part of everyday experience. Just because someone went through some effort to write down the effect doesn't mean nearly everyone already understands how it works and could also write down the "physics".

      Next we will talk about how it is amazing that a ball bounces off of something after hitting it... because of physics.

    3. Re:Contrary opinion by Anonymous Coward · · Score: 0

      So the headline is false?

    4. Re:Contrary opinion by Anonymous Coward · · Score: 0

      Stupid != false.

    5. Re:Contrary opinion by Anonymous Coward · · Score: 0

      "Maybe they didn't read the whole summary? Because I for one thought it was pretty cool they reduced the problem down to a canister and two tennis balls to demonstrate the same effect in an easier to understand way."

      Any of us with half a brain and interesting childhood could've told you how this works from our days of shooting bows and arrows, and tossing javelins and lawn darts.

      n00bs.

  17. Physics holds the key! by Anonymous Coward · · Score: 0

    Did you think it was going to be gender studies that explained "momentum and gravity"?

  18. It's *physics*?!? by Sebby · · Score: 1

    Really!? I thought all this time it was by magic! </sillyme>

    I guess that explains this teacher's ability to do so many flips then!

    --

    AC comments get piped to /dev/null
  19. Obligatory Jurassic Park quote by Diakoneo · · Score: 2

    "Your scientists were so preoccupied with whether or not they could, they didn’t stop to think if they should."

    --
    "Just as there is nothing so unreal as reality TV, there is nothing as unsocial as social media." - Alistair Dabbs
    1. Re:Obligatory Jurassic Park quote by Anonymous Coward · · Score: 0

      Definitely a contender for this year’s Ignobel Prize.

  20. It's because, of all the things they could have... by Anonymous Coward · · Score: 0

    ...researched, ... was there seriously not a single thing that was, I don't know ... more pressing? Or ... interesting? ... Or ... relevant in any way? ... Or even just more fun?

    It reminded me of that Idiocracy scene. (Ok, ... Like probably most things nowadays...)

  21. ORLY by Anonymous Coward · · Score: 0

    ORLY? So it's not BIOLOGY that holds the key? Or Chemistry?

    Quoting another post:

    "Was this from the "No Shit Department of Things That are Obvious"?"

  22. Comment removed by account_deleted · · Score: 1

    Comment removed based on user account deletion

  23. Re: I say, good work! by Anonymous Coward · · Score: 0

    I say, good work!

    Who are you, and what have you done with the real SuperKendoll?

  24. We don't need more physicists. by Anonymous Coward · · Score: 0

    There is an over-abundance of physic majors in our universities, and an extreme dearth of jobs for them. Getting young people interested in studying physics is harmful to them, given the present economy, as it sets them on a path of poverty and depression.

    Getting politicians interested in physics, to the point that they will allocate significantly more funding to research projects, would do our world a lot of good.

    I thought the article was fine. But flipping water bottles will not get us the money we need to get humanity to other planets. Or to become the Borg (note: this would be awesome).

  25. I found the headline useful by pem · · Score: 1
    All this time, I thought it was chemistry.

    Physics!

    Who knew?

  26. Physics Holds the Key to Walking Down Stairs by Anonymous Coward · · Score: 0

    No friggin' shit msmash.

  27. Wow. Just wow.. by Anonymous Coward · · Score: 0

    What a fucking waste of time....

  28. While this is kinda neat..... by bev_tech_rob · · Score: 1

    ......I wish the physicists of the world would get warp drive figured out instead........

    --
    You're messin' with my Zen Thing, man.....
  29. What in the goddamn fuck!!!! by Anonymous Coward · · Score: 0

    This story is fucking pointless. Why am I even replying to it?

  30. Missing explanation by Anonymous Coward · · Score: 0

    Rotation is entirely independent of translational motion. Videos and such do not explain why the bottle doesn't tip over (i.e., continue rotating) after it lands. The phenomenon demands a true explanation... WITH EQUATIONS.

  31. Ahhh, millennial by martinX · · Score: 1

    This is what happens when millennials are old enough to go to university.

    --
    When they came for the communists, I said "He's next door. Take him away. Goddam commies."
  32. Only General Flipping by Roger+W+Moore · · Score: 1

    The flipping water bottle trick only works for inertial frames of reference.

    Actually, it doesn't. It requires a gravitational force to cause the bottle to land. Since a uniform gravitational field is indistinguishable from a frame undergoing constant acceleration the flipping water bottle requires an accelerating i.e. non-inertial frame to actually work. Hence there is no Special Flipping, only General Flipping.