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Need some help for a mentos+diet coke experiment for my class!!

Discussion in 'Off Topic [BG]' started by DigMe, Sep 17, 2008.

  1. DigMe


    Aug 10, 2002
    Waco, TX
    So I do the mentos+cola thing to demonstrate to my 4th graders that gas takes up space. In the past I've just done a freehand launch where I slammed it on the pavement and let it go. I've gotten some good launches like that. One took a sharp turn though and headed right at some kids on the playground once. So now what I'm trying to do is I've got a 4 ft long piece of iron pipe that is about 6" in diameter and I want to launch the cokes out of it artillery style. I did some practice runs tonight though and no matter what I could not get them to launch out of the pipe at all. Some of them would just barely make it out of the end and some would not make it out at all. I would drop them in and let the cap end poke out of the bottom. Then I'd slam a big breaker bar into the cap to get it to pop off.

    When you freehand launch them they can fly pretty high with quite a bit of gusto but I couldn't get anything like that out of the tube.

    Any ideas?

  2. Josh Ryan

    Josh Ryan - that dog won't hunt, Monsignor. Supporting Member

    Mar 24, 2001
  3. GeneralElectric


    Dec 26, 2007
    NY, NY
    I know a good one, I used to do this to an exgirlfriend all the time as a joke since all she would drink was diet coke.

    You'll need:
    A needle
    Fishing line
    Bottle of diet coke

    Take the needle and poke a hole through the middle of a mentos. Thread a piece of fishing line through it and knot it so it doesn't slide down.

    Dangle the mentos into the top of the bottle (but don't let it drop) and pull the string towards the bottom to bring the Mentos to the lip of the bottle opening. Screw the cap on tight, all while holding down the string.

    Trim the extra fishing line. You shouldn't be able to see the mentos below the cap.

    When you open it, it drops in.

  4. Have you tried putting a backing plate and slamming it into the tube as you would the ground? Basically using the tube as a guide so it doesn't go flying at the wee little ones but the same concept as before.
  5. Marlat


    Sep 17, 2002
    London UK
    You want to demonstrate that gas takes up space? That's easy. Cut the cheese at the front of the classroom and tell your kids to put up their hands as they begin to smell it. When the kids at the back put up their hands say "see, gas expands throughout the room and thus takes up space". No need to endanger the kids with flying bottle rockets.
  6. DigMe


    Aug 10, 2002
    Waco, TX
    Yeah but that's way more fun for me than for them. I want them to have some fun too...not just smell my stink bombs.

  7. DigMe


    Aug 10, 2002
    Waco, TX
    Those are all free-hand. None of them that I saw on YouTube were shot out of a tube.

    You're worthless.

  8. DigMe


    Aug 10, 2002
    Waco, TX
    I could really use those Smash Lab guys about now.

  9. MakiSupaStar

    MakiSupaStar The Lowdown Diggler

    Apr 12, 2006
    Huntington Beach, CA
    Maybe you just have a case of a narrow urethra. :p
  10. mfgl


    Jul 1, 2008
    Altoona PA
    perhaps a long tube like a mortar, shake it up and shove it down the tube as hard as you can? when it hits the bottom maybe it will shoot out?
  11. Ripper


    Aug 16, 2005
    use pvc and something at the end for it to blast against
  12. GeneralElectric


    Dec 26, 2007
    NY, NY
    Actually Brad, my mentos on a string thing could work, so long as you have protection. Simply put more than one mentos on the string. Upend the bottle without opening it so the mentos touch the diet coke. Put in a clear box or something.

    It will explode.
  13. L-A


    Jul 17, 2008
    Here is a reference about what not to do.

  14. Vorago

    Vorago (((o)))

    Jul 17, 2003
    Antwerp, Belgium
    Ugh...I think this isn't going so well...

  15. jive1

    jive1 Commercial User

    Jan 16, 2003
    Owner/Retailer: Jive Sound
    bc went from fighting bull sharks, building security fences, and crying apache to being unable to shoot a menthos through a coke bottle.

  16. Brad,

    Have you tried using a nozzle with a bit more narrow opening? Just thinking a more concentrated stream of pressure will give the bottle the amount of thrust needed.
  17. DigMe


    Aug 10, 2002
    Waco, TX

    You're not getting the question. I have no problem putting the mentos in the coke bottle and closing the lid and all that. It's just that when I slide the coke bottle down the tube and then knock the end off when it gets to the bottom it's not taking off and shooting out the tube like I want it to.

  18. DigMe


    Aug 10, 2002
    Waco, TX
    I tried the tube thing but it wasn't shooting out.

    I was thinking about PVC tube with a cap on the end and maybe a big screw or nail poking up in the middle but then I was thinking that I don't know if the hole made by the nail when it slams down would be a big enough hole to allow enough liquid out to actually launch it.

  19. Happynoj


    Dec 5, 2006
    I like turtles.
    Maybe try a shorter tube?
  20. DigMe


    Aug 10, 2002
    Waco, TX
    It really shouldn't make any difference since I've seen these bottles shoot as high as 40 or 50 feet or maybe more.


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