Intro: Backwards Water - Real Life Gravity Defying Water
A while back I was watching an episode of "Breaking Magic" which is a television series consisting of amazing scientific stunts and experiments when I saw something that was quite amazing... Gravity Defying Water! I thought to myself "That is so cool, I just have to try it!"
The clip of the amazing stunt is above.
This stunt works by using a combination of light and sound. A low frequency sine wave is sent through the speaker and makes the pipe over the speaker vibrate. When the frequency of the strobe light and the speaker are matched the water appears to stop in mid air. Taking the frequency of the speaker slightly more or slightly less than the frequency of the strobe either makes the water look as if it is slowing down (taking more time to reach the bottom) or going backwards (the water looks like it is being sucked from the bucket and back up the hose).
So here is my version...
Note: This instructable involves using electricity and water near each other. Care should be taken to prevent water coming in contact with any electrical components.
Step 1: Gather Parts
There are a few bits and pieces needed for this stunt as follows:
- 3x Cable Ties.
- 2x Self Adhesive Cable Tie Holders.
- 1x Large speaker with exposed cone (I used an old sub-woofer from a surround sound system with the cover removed. The speaker cone must move a lot, so for example PC speakers are not suitable).
- 1x Large bucket.
- 1x piece of solid pipe that twice as long as the height of the speaker. (Flexible pipe doesn't work well here because it absorbs too many of the vibrations from the speaker. The piece I'm using is 15 mm plumbing pipe).
- 1x Strobe light (the faster it flashes, the better).
- 1x Car radio (or something to drive the speaker).
- 1x Garden Hose and water source.
- 1x Device that is capable of producing a low frequency sound with an audio out (I used a laptop with software called audacity to produce the frequency, however I know there are various apps available for smartphones that are also capable of doing this).
- 1x Length of speaker wire.
- 1x Dark room.
- 1x High shelf or table to put the speaker on (I set my version up in the roof space of my workshop so it had a long distance for the water to fall).
If you wanted to recirculate the water you could fill the bucket and use a pond pump and a piece of garden hose that fed the solid pipe. This an alternative to getting fresh water from the tap.
Only a few basic tools are needed:
- Wire Cutters or Scissors (for stripping the speaker wires and cutting cable ties).
- Small saw or other tool to cut plastic pipe. (Be careful when using sharp tools).
- You may need a small screwdriver if you insulate the speaker connections with a terminal block or for prying off the cover of your speaker.
Step 2: Modify the Speaker
To modify the speaker you will need to take the self adhesive cable tie holders and stick one of them to the speaker cone and the other above the speaker cone on the speaker body. The diagram above identifies these correct positions.
The top cable tie holder acts as a pivot point to the pipe as it moves with the speaker cone. The second cable tie holder on the cone makes sure the pipe is held tight to the cone as it vibrates.
Next, take a cable tie and push it through the cable tie holder on the cone.
After you have done that, take the hard plastic tube and cut a small section off the end (1.5 cm - 3 cm depending on the depth of your speaker cone). This will act as a spacer to ensure the pipe is in the right place.
Push both ends of the cable tie in the holder through the spacer (as shown in the image above).
Rest the pipe between the cable tie protruding from your spacer making sure that the pipe exceeds the base of the speaker (as shown) and tighten them up around the pipe.
Using another cable tie, Attach the pipe to the top cable tie holder.
Congratulations, you have successfully modified the speaker!
Step 3: Make Connections
The next step is to connect all the wires and pipes.
Firstly, connect the car radio to a power source by identifying the correct wires for your make and model.
Identify the correct wires for the speaker output and connect the speaker wire. It would be a good idea to insulate the connection with something such as a terminal connector, electrical tape or heat shrink tubing.
Connect the other end of the speaker wire to the speaker.
Next, attach the garden hose to the solid plastic pipe by pushing it over the end and securing it with either the third cable tie (as pictured) or a jubilee clip.
Connect the other end of the hose to a water source such as a tap or the pond pump if you went with that option.
Plug the 3.5 mm audio jack to the car radio and connect to your computer or whatever device you choose to use to produce the frequency.
Step 4: Setup in Position
Go to the darkened room where you want to set up the stunt and position the speaker on the high shelf or table top (in my case I set it up in the roof of my workshop so it has a long distance for the water to fall to the collection bucket on the ground).
Power up the car radio and turn on the strobelight.
Step 5: Create the Frequency
In this step you may need to experiment with different frequencies according to the speed of your particular strobe light.
Turn on the water supply to a moderate but even stream of water. If the tap is on too slow then the stream of water will just create a shower when the speaker is turned on. However if it is too fast it will likely splash everywhere and make a mess, so play around a bit until you get it just right.
Turn off the lights and go to your computer or other chosen device. For this I used a piece of software called Audacity which is a great for audio editing and I have used it for many applications, however what is great is it has a tone generator which is what we need for this project.
Once installed from the Audacity website (http://audacityteam.org/) launch it from the desktop and it will open onto the main editor. Once there look along the top bar and go to "Tracks > Add New > Stereo Track"
Once you click "Stereo Track" a blank track will open in the editing area.
Next look at the top bar again and go to "Generate > Tone " and a new window will pop up.
This is were a bit of experimentation is needed. A good place to start is 20 Hz which you may or may not be able to hear as humans can only hear from about 20 Hz to approximately 20,000 Hz. Once you have typed 20 Hz into the frequency section make sure the amplitude is set to 0.8 and the duration is set to as long as you want the effect to go on for (i.e. 30 seconds, 1 minute). Once all set press "OK".
If you get stuck then follow the images above.
Make sure your volume is turned up and "Audio In" is selected on the car radio.
Press play and you should see the plastic tube moving slowly in a side to side motion.
If the water doesn't appear to be standing still then close the track with the small "x" on the left hand side of the screen and start again by going to "Tracks > Add New > Stereo Track" and then "Generate > Tone " this time try a slightly different frequency such as a few Hz less than before. Just keep trying until the water stands still in mid-air.
Step 6: Play Around and Have Fun!
Be creative with this effect!
Above is a video of my results.
Once you have found the frequency at which the water stops in mid air you can do some real cool things:
- To make the water go slowly, add 2 Hz to the frequency you have discovered.
- To make the water go backwards, take off 2 Hz from the frequency you have discovered.
These are the frequencies that I have found work with my strobe:
- Up = 15 Hz
- Stop = 16.7 Hz
- Down Slow = 19 Hz
Ideas of things you could do with this effect:
- Use it as a party or disco centerpiece.
- Add some music to the effect and present to family and friends as part of a show.
- Entertain your kids and let them play around with the different frequencies.
- Play around with the position of the strobe and the speed of the water to find the strongest effect.
- Freak out friends at a Halloween party.
If you have any problems in getting your stunt to work please comment and I will try my best to help you out!