Potato Cannons, also known as Ethnic Cannons (or Polish Cannons, if you don't want to be politically correct about it) are one of the most awesome high school physics experiments ever.

In the good old days, you used to be able to make your own Ethnic Cannon out of beer cans and lots of duct tape, because beer cans were made of steel. DO NOT use aluminum cans, as the explosion required to launch the potato on its flight of glory will blast straight through the crappy aluminum like a hot potato through butter. If the idea of making your Ethnic Cannon out of cans is just too appealing to you, go to an Asian foods market, as many Asian softdrink companies still use steel cans. Otherwise, use a fiberglass tube.

If you want to have Phun With Physics, get yourself a plastic gallon icecream bucket. I recommend Blue Bunny. If you do not live in a country with gallons, just find a large icecream bucket. Maybe 2 or 3 litres, or so. Anyway, turn this bucket on its side and attach 2 ring hooks, one near the top, and one near the bottom of the bucket. Tie a piece of rope to each ring hook, and attach the other ends to a beam, or the ceiling. Something that is solid and not going anywhere.

    ==o===o==  Beam
      |   |
      |   |  Ropes (3 ~ 4 feet)
      |   |
    |-o---o-|
Top | >(:x) | Bottom
    |_______|

Now, set up some sort of grid on a large sheet of paper or a blackboard, and hang the bucket in front of this grid from a side view, as shown in the diagram above. Now, pack the bucket full of insulation, you know, that pink stuff in your walls. This will keep the potato from smashing through the back of the bucket.

Now gather your friends or students around to be observers. As the potato exists on the macroscopic level, the laws of quantum physics will have little effect, so this should not change the result. Get one person to aim the cannon into the bucket. Have this person level the barrel of the Ethnic Cannon with the center of the bucket, with the end of the barrel of the gun about 4 or 5 feet from the mouth of the bucket.

DO NOT hold the cannon bazooka style, on your shoulder, instead, steady it near your waist, like Rambo with an automatic rifle. This way, if the cannon does explode, it will not destroy your head, but will only sterilize you as bits of Ethnic Shrapnel and flaming potato lambast your genitals.

Fire the cannon. Your observers should watch the bucket swing back and up on the ropes like a pendulum. Have them note which grid mark the bottom of the back end of the bucket reaches. You can now estimate the force created by your Ethnic Cannon.

As a neat little bonus, the rapid accelleration of the potato by the Ethnic Cannon, followed by the rapid decelleration by the insulation-filled bucket will cook the potato nicely. I wouldn't recommend eating it, since the potato will also probably have little insulation fibers sticking out of it.

Thanks to Jerry Wilkes, the most awesome physics teacher ever. Have a happy retirement.