Figuring Out Acceleration on a Potato Gun Answered
My newest craze is potato cannons. I built a simple potato cannon powered with hairspray. I didn't plan out ratios of chamber volume to barrel volume, but I must have guessed pretty well because the potatos go far. Really far. I shoot them in an empty bean field and they stay in the air for 10 seconds before hitting the ground at what I guess is 300 yards away. I want to measure it to be sure. I'm probably exaggerating the distance out of sheer amazement. But the potato goes really far.
I got to thinking, though, that I could go beyond just shooting the potatoes, and actually turn this into something useful. If there was a way to determine the acceleration of the potato inside the barrel, that would be super cool. I've had a few ideas on this so far:
The most complicated involves drilling holes on each side of the barrel. The holes would be every inch the entire length of the barrel. On one side led's would be installed and wired in parallel to remain on constantly. On the other side photoresistors would be installed and also wired in parallel with a microcontroller. When the potato traveled down the barrel it would block the light to some of the photoresistors and the microcontroller would get a readout. If there was a way to program this whole system and get a graph on a computer of the acceleration/time curve, that would be awesome!!
Another way would yield a less accurate number. Shooting the cannon straight up and timing how long it takes the potato to hit the ground would give you the initial velocity. Vf = Vi + Gt, so: -2Vi = -9.81t . Once the initial velocity is known, if the time it takes for the potato to leave the barrel can be figured out, the acceleration could be figured out.
Let me know what you think!
Note: I will attach images as they come.