A Simple Funny Physics Experiment




About: I have a background in chemistry, molecular biology and immunology and I am working in the field of in vitro diagnostics and life sciences. I like the concept of citizen science, and my intension is to simp...

How to get some liquid out of a bottomless bottle without turning it?
A simple do-this-at-home experiment

This Instructable is based on an accidental observation.
It might take a scientist to find things like this funny, but maybe you do as well.
And given, you are working in theoretical or experimental physics: can you give a sound explanation of this phenomenon?

When I was playing mindless with a nearly empty, reclosed PET (!) orange juice bottle, it fell screw cap-down on the table. I then saw the residual liquid in the cap jumping up when the cap of the bottle hit the table.

Not really surprising as such, but it does in a single, narrow, staight column, reproducibly. I have been using my mobile to document the process (see images).

As an experiment with a Pepsi bottle showed, it is working even better if a bottle with a smaller screw cap is used. Here the liquid column can hit the top (former bottom) of a larger bottle. Or, if you remove the bottom of the bottle,it will spash upwards, reaching estonishing heights.

What could you do with it:
You may use this phenomenon to trick somebody (preferentally parents or teachers) or you may place a bet that you can remove/get some of the liquid from the bottle without turning it or touching the liquid.
Some may make a drinking game out of it.

- Take a empty PET bottle. Remove the bottom with a knife or a pair of scissors.
- Fill a few milliliters of some (colored) liquid into it (amount to be optimized for the individual bottle).
- Hold the bottle at least 1 meter above a hard ground. Carpet floor will not work.
- Release bottle.

Depending on the liquid, you may either try to fetch it, or you better remove your head.

Have fun playing.

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Step 1: Open Bottles: Example 1

Trying to be able to see what is happening in the cap of the bottle and how high the liquid can splash, I removed the bottom of the bottles. Interestingly, using a 1.5 ltr Pepsi bottle, parts of the liquid were splashing higher then the starting height of the fall. You can have a look on the realtime movie, but you will see more details on the individual images.

Step 2: Open Bottle: Example 2

Here I used an orange juice bottle with the bottom removed. Please have a look on stills and movie.

Step 3: Reproducibility: the Same As Before

Just to show that the phemomenon is quite reproducible:
compare these with the images on the first step.
This just has been another try.



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    9 Discussions

    the downward force of motion of the liquid before it has reached the bottom of the container is combining with the return force of the vibration of hitting the surface. Although probably not noticeable so, the vibration is amplified by the 'shaped charge' effect of being contained in a higher pressure environment (the neck of the bottle) exploding into a lower pressure environment (the body of the bottle) and the discharge of air around the liquid dissipates circumferentially around the liquid burst in the center, keeping it centered in the bottle, relative to the angle of impact, as that would also affect the angle of vibration... well, that's my guess anyway lol... interesting experiment, thanks for sharing.

    Dr H

    3 years ago

    I like both concepts and both might be correct, at the same time.
    The transfered energy probably comes from the whole bottle, and the finding that the liquid builds up a single thread may come from a wave superposition sounds quite reasonable as well. The question would be how to prove these ideas and how to enhance or break these effects individually. Let me know your suggestions and experimental results.

    One thing I would like to see is a numeric simulation that can predict the effect.


    3 years ago

    Hi. That is very funny and I have to do this with my kids at home later.

    In my opinion it is a superposition of waves. As you can see in one video from the top the liquid moves to the wall of the bottle when falling. The center is empty. That is because of the mass inertia and the cohesion and adhesion of the liquid and the bottle. When the bottle hits the ground the liquids moves down into the cap with high speed. This centrical wave superpositions in one small point. Like a monster wave in the ocean. Waves superpose and result in a very high waterpeak. This motion is like a drop falling into water but reversed direction.


    3 years ago

    If you do this on a very cold day, will you make an icicle? :D

    1 reply
    Dr HSidA2

    Reply 3 years ago

    An interesting question. In theory it may work, if you would use very pure, particle-free water in this special undercooled state. The energy of the impact should be enough to let it snap-freeze. An other, room-temperature friendly option would be an over-saturated solultion of sodium acetate (the stuff used in this hand-warmers) that can solidify within seconds.
    Well, try and let me know.


    Reply 3 years ago

    Thanks, but: take a cheap chinese mobile to take the videos, VLC to run the videos, then ma screenshots for the stills and GIMP to crop them. Anyone can do it that way.


    3 years ago

    like dropping a tennis ball on a basketball! Cool observation, does the bottle bounce? does an empty bottle bounce? maybe the force after the impact is transferred into the smaller mass of liquid making it go flying.

    1 reply
    Dr HWolfbane221

    Reply 3 years ago

    sure the bottle still bounces a bit, but presumably less than an empty one. So far I have not experimenting with different volumes or liquid with different viscosities.

    What has been really fascinating me was the fact that even though the cap of the orange juice bottle was relatively large, the stream shooting up is a cone giving arelatively thin thread. If you look on the pictures taken from above, it seems that during the fall the center of the cap nearly empties and then may shoot down and meet in the middle of the cap when the bottle hits the ground, redirecting the impulse upwards to build up that single thread. But the majority of the energy may come from the shockwave from the input.

    To see this in more detail a camera with a significantly higher frame rate and a optimized setup might be necessary. One may optimize the process by adding a tip to the center of the cap. Any suggestions are welcome.