Brad Singleton
J. Aaron Tullos
Ryan Connors
Happy Year End! - A Rube Goldberg device
Our project was titled Happy Year End due to its final task performed. Through a series of energy changes, we enabled our device to jerk a string to fire a simple party popper novelty. The device is rather uncomplicated. We started by building a rectangular wood frame. We then collected two water bottles, one acting as a pendulum weight and the other as a stationary mass. We decided that we would attach the party popper to the top of the frame and a string from that to the mass, making the pendulum hit the stationary water bottle to knock it off an elevated edge, thus firing the popper. Hooks were attached where needed for the pendulum to start at the top and swing to hit the mass at the bottom of its path. We then needed a creative way to release the pendulum so we constructed a pivoting lever with a razor attached out of two paint mixing sticks, a nut, two washers, and a bolt. A hole was drilled into the non-pivoting stick and a small nail was inserted to hold it open. We put another nail into the frame and hooked a rubber band around that and onto the lever to give it a spring action when the nail is removed, thus cutting the string that held the pendulum at its initial height.
Our design process was rather simple. Ryan works at the Fireworks Supermarket close to Farragut, so I figured we needed to incorporate something from there into our project and the only thing I could think of that would be appropriate was flameless poppers, so we began there. After we got the poppers, we went to Ryan’s house nearby and began looking through his garage for random items that could be used for the construction of our device. We started with building the wood frame from scraps and found a roll of fishing line just went from there. Originally we were going to use a shoe as the pendulum, but then we realized the water bottles would be much easier to work with.
During the brainstorming process, we had a few other good ideas before we just decided to go with the random creative route. Our first idea was to build an EF 151 extra credit dispenser. It was going to be a tennis ball catapult with just enough trajectory to launch to one of our classmates. We also had a plan to create a small car powered by the spring force of a mouse trap. The plan was to use that to hit a trigger, releasing a spring to perform some task. Although we had many sketches and ideas, we just worked with the free materials we had and spent as little money as possible.
Overall, our team spent very little money. The money that was spent was at Walgreens for the razor blade which cost two dollars, and drinks that we supplied to the class as part of our presentation. Ryan also spent a dollar on the party poppers. We figured if we were to buy all the items used in the device, the cost would have totaled around fifteen to twenty dollars.
Several energy conservations were depicted in the performance of our Rube Goldberg device. The rubber band causing the spring force displayed elastic energy. When this releases the string holding the pendulum, potential energy converts to kinetic. Then the swinging pendulum knocks the stationary mass causing kinetic to gravitational potential. The gravity that accelerates the falling mass pulls the string of the popper. The gun powder that explodes displays chemical energy to kinetic energy. The end result is potential. The result of our calculations include: k=.23 lb/ft, w=2.2 lb, x=.5 ft. So, .5kx2 + m1gh + m2gh = 15.525 Joules before the pendulum is released. After the firing of the confetti popper and has reached its final height, the energy is .0383 joules. This results in an energy loss of 99.7% meaning that it is .3% efficient.
In conclusion, this project was fun and a creative way to apply physics to a self built device. We didn’t experience any difficulties or problems other than having to buy a new razor because the old one we had wasn’t sharp enough to cut through the fishing line with the given spring force. Our project and presentation overall was a success! We all put forth an equal amount of idea and effort into this project. No resources were used other that our own creative ability.