How to Make a Spin Rocket Cartesian Diver

Two Methods:Small Bottle MethodStraw Method

This is a variation of a Cartesian diver. This Cartesian diver can also demonstrate Newton's third law of motion (action and reaction forces), as it spins its way through the water.

Method 1
Small Bottle Method

  1. 1
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    Cut the bottom off of a small, plastic sauce bottle.
    Refer to the Things You'll Need section for details on the bottle size.
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      Cut the bottom, not the edge, when you make this cut.
  2. 2
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    Put a couple of plastic beads into the bottle, then force a glass marble into the bottom end.
    You can just see a small, yellow bead on top of the marble in the photo.
  3. 3
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    Use a thumbtack to poke a hole in the side of the bottle, just above the marble.
    Refer to the tips to see exactly where to put the holes.
  4. 4
    Decorate the small bottle with water-resistant tape so that you can see the bottle spinning.
  5. 5
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    Fill the larger plastic bottle with water and put the smaller bottle into it.
    The inner bottle will have air in the top. The marble should cause it to float upright.
  6. 6
    Screw the cap on securely. The outer bottle must be airtight.

Method 2
Straw Method

  1. 1
    Put a couple of plastic beads into the straw, then force a screw into one end. See How to Widen the End of a Plastic Straw.
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    2
    Burn the other end of the plastic straw closed.
  3. 3
    Use a pin to poke a hole in the side of the straw, just above the screw. Refer to the tips to see exactly where to put the holes.

    • Alternatively, you can make a u-shaped diver by bending a straw in half (along the bendy section that some plastic straws have) and putting screws on each end.
  4. 4
    Decorate the straw with water-resistant tape.
  5. 5
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    Fill the larger plastic bottle with water and put the straw into it.
    The straw will have air in the top. The screw should cause it to float upright.
  6. 6
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    Screw the cap on securely.
    The outer bottle must be airtight.

Tips

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    Side view of where to poke the holes in the small bottle.
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    Top view in cross section of where to poke the holes.
  • Image titled The arrow shows the direction of rotation.
    Here's how to make pin holes if you have a u-shaped straw diver:
    (Please consult the 3rd video.)
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    Squeezing the outer bottle gently pushes water into the smaller bottle. The air in the inner bottle is compressed and the inner bottle ceases to float. When the outer plastic bottle is released, the air in the inner bottle expands, expelling some of the water, and the bottle floats again.
  • The bottle spins because it expels water through the off-center pinholes, just as a rocket ship moves by expelling burning fuel.
  • The beads will spin in a spiral to further illustrate the physics of this diver.