Potato Cannon Part 1

           OK, a bit late because I had to go to a camp for a week, but here it is. I haven't completely finished the cannon so I'm going to do this in parts. First part is to get the materials and glue the PVC piping together.

So you'll need:

• A 5in x 2ft piece of PVC piping (combustion chamber)
• An end piece with a screw on back (end cap)
• A 5in to 2in pipe reducer (if you can find one of these you can just use a 5in to 3in and 3in to 2in reducer with a small 3in pipe in the middle)
• A 2in x 4ft piece of PVC (barrel)
• A grill ignitor 
• PVC Primer & Glue 
• Spray Start (Propellant)
• Sandpaper

Note: You can use ABS instead of PVC, it tears instead of shattering making it slightly safer if your cannon exploded, the only thing is that it's much harder to find, personally I think PVC's fine, it's what I used in my cannon.

          You can all the PVC piping, PVC primer, PVC glue, and the grill ignitor at Home Depot and then you should be able to find Spray Start at any auto shop, all in all it costs about $50.
          
           Once you have all the materials you first need to glue the PVC piping together. One thing you have to remember is that the glue is nasty, it essentially melts the PVC so it becomes one whole. You do not want to breath too much of this stuff, so work outside or in a well ventilated area. Before you start gluing, you need to sand down the edge and 2-3 inches down the side of the ends that you'll be gluing, this helps the glue have an area to seal, so there's no paint in the way, and so you can push the pipe all the way into the reducer. After you've done this, apply the primer and glue to the area you sanded on the combustion chamber and end piece and quickly push the pipe into the end piece while quarter turning it until it bottoms out. Once it's in, hold it there for about 30 seconds so it doesn't slide back out. Do this again with the other pieces and you've made the body of the cannon.
          
           Before you do anything else, let the glue set for 48 hours so it can harden. This is the end of part one, next part is how to install the grill ignitor, wrap the PVC, and test it. Hopefully I'll get the cannon to work and I'll post it in a couple of days.

Potato Problems

Grr... Potato cannon's finished but i just can't get the fuel to ignite in blank tests. I'm planning on posting the first part by tomorrow, hopefully I'll get it to work but I can't do much right know, it suddenly started raining soaking everything.

Potato Cannon!

Hopefully by the end of the week i'll have made a potato cannon and a couple days after i'll post how to make one!

Hot Ice?

OK, this is something cool I did a while ago. "Hot Ice" is is sodium acetate, you get it as a white mush from the volcano baking soda and vinegar reaction along with carbon dioxide (maybe I'll do that sometime), that is supercooled. Supercooling is where you take a liquid and cool it down to lower its normal freezing point without its phase changing (the state of matter it's in, solid, liquid, gas, and plasma). You do this by making the liquid totally pure. When a liquid turns into a solid, it becomes a crystal. There is the exception of amorphous solids like glass, that are physically solids, but have no order between the atoms and do flow, they are just very viscous, so it takes hundreds of years. For a crystal to form, it needs an object to grow off of. 

When water is completely pure, it has no dust in it to start growing crystals. Water normally it freezes at 0 °C (32 °F), but when it's pure, it freezes at -42 °C (-43.6 °F). It's able to do this because the water molecules start clumping together so tightly that they form an unstable crystal that melts at a temperature higher than -42° C. That allows the water to form crystals. 

Sodium acetate does the same thing. Since it is not a liquid at room temperature, it has to be dissolved in a liquid. You have to have a lot of sodium acetate in the solution, so you have to supersaturate it by heating up the liquid and dissolving the sodium acetate so more of it is in the liquid than you normally could dissolve. It's like rock candy, you dissolve as much sugar as you can in boiling water, supersaturating it, and then place a starter crystal and after about a week, it forms a giant sugar crystal. So after supersaturating the sodium acetate at around 58 °C (136.4 °F), and then heating it up to 100 °C (212 °F), you cool it down to room temperature. There you have it, all you have to do it touch it and it will crystalize and heat up in an exothermic reaction (it does this because of electron spacing allows atoms not to hold as much energy, so they release it as heat. I'll explain it in another experiment). 

You can get powdered sodium acetate online to do this but you can also just go buy some hand warmers (I got a couple at REI). They're plastic bags filled with a clear liquid (sodium acetate) with a metal coin that you flex to start the reaction. I tried to make some, concentrating the white mush from the baking soda and vinegar experiment. The proportions weren't correct so there was left over vinegar and baking soda so that most of it decomposed when I concentrated making it brown and the rest of the impurities made it crystallize. Well, I hope you thought this was cool, I have a video posted of one of the hand warmers, and if I ever make my own sodium acetate I'll post that too. Oh, also here's a recipe for making the sodium acetate with baking soda and vinegar.

Sorry!

I haven't been able to update this every week and I'm not going to try. I have too much going on, and I don't have time to even think of cool experiments that I could tape. If you have any ideas, post them in the comments.

Dancing Corn Starch!?!?!

Hey, yesterday I did a totally awesome experiment with dancing corn starch. I suggest doing this in the basement or out side where it's okay to get messy and there's an outlet. You'll need a junky old speaker to use and you'll have to hook it up to an amplifier with a computer to generated the sound. I use a Mac so I got a free app called Tone Gen from the apple website so for those who have PC's you'll have to look around or hook up a keyboard. You'll need the corn starch (you can find it at super markets) to be at the consistency that you can punch it with your fist and it will be solid. For those who don't know what corn starch is, it's a powder used as a thickener in gravies instead of flower and if you mix in with water it has the cool property of being "Non-Newtonian", meaning when you squeeze it, it's a solid and when you let go it's a liquid. So, when you mix up the corn starch I suggest putting it on a Styrofoam plate if your speaker cone is cloth, and putting the plate on a plastic bag so you don't end breaking the speaker. Then if you have the app set it to a single tone ( I suggest 28 Hz if your speaker can go that low, though it works to about 35 Hz). If you only have a keyboard you'll need to go as low as you can and if you have a tuba setting you should do that and crank up the volume as high as it can go without the amplifier burning a fuse or the speaker popping. once you have this set up, hopefully it will start wiggling in the middle and you can get it to move around a pit by poking it with a pencil (or using your hands ;-). If you have the computer set up you can play really loud music in the background :-) So, you know, the louder the volume the more it moves around.  

             So what I think is happing is that with all liquids low sound makes them vibrate and make cool patterns. With corn starch it has more of a structure with all the vibrations, becoming semisolid making the patterns be able to "climb". while this stuff is out a fun thing to do is to do a hearing test. Start at 1 Hz and go up on single tone with the plus and minus buttons in the top left corner, seeing how high and low you can hear.

         note: be careful when going to high Hz and let the tester change the volume so you don't end up shattering their ear drums. Also, don't listen to the high notes for more than a minute or two because it might cause ear damage.

Hey, hopefully every one or two weeks I'm going show a cool science experiment and video along with it. I'll keep this going for a while and putting things in as I do them, trying to keep them simple enough to do at home.