Expieriments with Physics

Allatoona Damn

A friend I grew up went to Georgia Tech. He majored in physics.

For a while he, as a student, he was quiet taken away with the mathematical physical science of objects, which led to a few experiments.

Once he wondered what would happen if one shot a shaving cream compress canister. Would it spew out, or would it take off like a rocket spewing or what? So, we bought a new can of shaving cream and we got my .22 rifle and we went out in the woods. We put the canister on top of a stump and shot it. I don’t remember, but I would guess that it probably took several shots before we hit it. But when we did, the compressed cream did shoot out and the can did not stand still. The can almost suspended itself in midair and it spun. When I saw it spinning in midair, leaving a trail of liquid soap around and around it made me think of a galaxy.

Our second experiment, my friend was curious if we took a stack of note book paper up to Allatoona Lake Dam and made paper airplanes and throw them off the dam itself, what would they would do. It is a big dam. I don’t know how it compares to the Hoover Dam, but it is huge. One side is Allatoona and on the other side is an almost straight down cement cliff that must be several hundred feet down. It seems that way anyway. And at the bottom is the Etowah River which flows by Cartersville, the Etowah Indian Mounds, and then Rome, Georgia. I don’t where it goes then. The Etowah River is at the bottom of a very long valley. And at the dam interrupts the valley. It is windy on top of the dam. The wind is carried down the valley, almost like funnel, hits the dam and then goes the only place it can -straight up. We made a few paper airplanes and threw them off the edge. With the wind coming down the valley, then hitting the dam, and turning vertical and shooting upward was what he had in mind. Each airplane seemed to stay airborne a very long time, before it got knocked off the route of the upward wind constant blast. One paper plane may be still there. We got tired of watching it and left with doing what it has been doing for over an hour. It would go high, then out of reach of the upward wind, then fall down, and the wind would catch it and up it would go again. Over and over. Ho-hum.

The third experiment, my friend bought a 57 Chevvy convertible to do his share in a car pool of other Tech students. It was two-tone aqua and white. He came by to show me his car, it was clean and did not have a dent or scratch on it. We went for a ride in it with the top down. We had a few cans of beer. I don’t remember why, but we got onto an old dirt road out near Dallas, Ga. That road is a place we regularly went and parked our cars, and walk through a little clump of woods to slip into the Dallas Drag Strip. At the moment my friend was taken away with Einstein’s Theory of Relatively (E=MC2). I know, I know, the 2 is supposed to be smaller. I asked just what the theory was about, in layman’s terms please.
He said in its simplest form, say you are on a bus, standing in the aisle. You mark an X on the floor where you are standing. Then you jump up and land. Where do you land? You land on the X. Shouldn’t you land several feet behind the X because the bus, more or less will travel out from under you, or at least it seems the X should travel out from under you. No, whether you know it or not, while you are standing there you are also traveling forward at the same rate of speed of the bus. So when you jump up, in midair you are also flying forward at the same speed of the bus. And on the other hand, if you should jump up in the air and the bus stops suddenly, you are still traveling but the bus isn’t, so you should land up several feet in front of the X, closer to the front.

So, I said, “You mean, if I throw this half-full beer can up in the air, the same time you suddenly stop, the beer can should land in front of the car?”

He confirmed that it should.

OK, lets try it!

On the count of three I threw up the beer can as straight up as I could and at the same moment he slammed on the brakes.

The beer can went up, then back down.

WHUMP!!!

The beer can hit his hood and put a mall dent on it.

So much for experiments.