# Homework Help: Potato gun

1. Mar 7, 2005

### SelmerSaxMan

For a physics project, I really want to do something with an explosion in it, but I can really only come up with one practicable idea - a potato gun. Practicable meaning, an idea that won't cost me much more than 2 hundred dollars in instruments and materials. I plan to find out how much energy is contained in some sort of propellant, then vaporize it with a spray bottle and calculate the kind of force that the particular charge is capable of producing to find the efficiency of the reaction based on the height that the potato reaches. I am thinking of using white gas in a potato gun made of that black PVC pipe - is this a safe idea? if not, I will use alchohol. I have a very good physics mind - math is ok too, but not my strongest point. Could any of you help me with this project? Or even better, coulda any of you help me think of an idea that involves an even bigger explosion that I could use for a lab? :)

I know that this is getting awefully close to chemistry, but hopefully the use of projectile motion in here and conversions from joules to newtons will make it close enough for my teacher. Please reply as soon as possible, I already had a completely different idea before this one, but I couldn't get a hold of a 11,000 gauss magnet that I really wanted for it. So, I have 3 days left before the proposal is due. thanks for any and all help in advance.

2. Mar 7, 2005

### vitaly

We just made a potato gun in our physics class... Ours was made of white PVC pipe (simply because that's what Home Depot had and we didn't feel like changing anything). Black is suggested in many websites, though, so it's a good idea. As for the propellant, we used hairsrpay, but another team used something else, I think. From what learned, the propellant is not as important (it still is important, though) as the timing and temperature. It's better to try it in cooler weather, and you have to be quick. Right after you spray inside, you have to ignite the gun. Otherwise, it won't shoot. The amount you spray is also important. So, if plain hairspray worked, alcohol and whatever else you plan to use should work.

As for safety, just make sure there is a fire extinguisher present. If anything drips on the ground and a flame is ignited, a fire can obviously spread. Oh, and make sure it's legal in your area, or make sure nobody else finds out.

Good luck.

3. Mar 8, 2005

### 1+1=1

SelmerSaxMan, have you ever seen/used/shot a potato gun? If not, and you decide to make one, they are one bad ace. Can anyone else vouge for this?

4. Mar 8, 2005