Duck It Rube Goldberg Device Group 3

Transcription

1 Duck It Rube Goldberg Device Group 3 Katie Peay, Brandyn Hoffer, David Hudson, Anthony Rose Executive Summary Duct It is a fairly simple design that was constructed to lift a single kilogram mass one meter above the ground. The device was built with wood, nails, a metal rod, a mouse trap, 2.2kg weight, and an extremely large amount of duct tape. The contraption was designed to use gravitational potential energy and spring energy simultaneously to accomplish a task. We faced many challenges when constructing our machine due to the inconsistency of the rubber bands and the strength of the wood. Although many problems arose, through hard work and perseverance, we prevailed with a machine that worked as well as we could have hoped. Design Process The design process was a long and rigorous one. The initial meeting we held we discussed how we would go about building our Rube Goldberg machine. We made a list of household objects including hammers, rubber-bands, and marbles. We had a lot of good ideas; however, every time we went with an idea, something horribly wrong would always pop up. The original design with a hammer and pulley system was flawed right from the beginning; yet we were not discouraged. We remained tenacious in our duties and derived new plans from the original design. In the final design, we managed to keep the use of a hammer to set off a weighted pulley system. Our team also managed to keep the rubber-bands to add tension to the pulleys making sure the device was able to lift the weight. The frame on which the device stood and the final location of the pulley system changed the most throughout the project. Overall, after 20 some-odd hours of working through disasters, we came up with a somewhat working design. We sacrificed the time limit of the machine in order to pull up the 1 kilogram mass one meter. The machine could lift the weight up one meter, but it

2 accomplished it in about one to two seconds. Fortunately, we did manage to turn out a machine that worked 80% of the time, and did pull the weight one meter. Device Description The final design turned out to be quite an interesting one. The dimensions were in the guidelines of a meter long and half a meter high. It started with a marble setting of a mouse trap. The mouse trap set off a hammer, which were tied together by a string. The hammer had a metal bracket attached to it by a string which was pulled down when the hammer swung. The metal bracket held the weight back. A rubber band was attached to the weight and stretched around a rod for tension. Once the metal bracket released the weight, it was a mere second or two before the device actually worked. It raised the 1 kg mass 1 meter with an almost slingshot effect. Our idea was one of the few that used rubber bands. Energy Conversions We did the majority of our calculations on a separate sheet of paper attached at the bottom of this report. We made assumptions ignoring friction and wind resistance. We had to estimate the spring constant in the mouse trap with an online calculator. Overall we found our project to be 80% efficient. Summary of Costs Our team did our best to use object we already owned. We actually only purchased the twine. The wood, pulleys, and mousetrap were found in the EF room as scraps from old projects. Everything else was found around our houses. We estimated the relative costs of each object. The only thing we were able to salvage after the project was the hammer. Out mousetrap broke under the tension of the rubber band. Twine $2.54 Wood $5.00 Weight $5.00 Pulley $0.50 Mousetraps $4.00 Marble $0.06 Duct Tape $2.00 total $19.10 Summary Our project was operable but not entirely successful. Although our design led to a machine that was capable of lifting a one kilogram mass, we fell short of the required one meter height by a quarter of a meter. Making this take place in ten seconds was another area we did not achieve much accuracy. Upon designing our machine, we had few ideas of how to slow it down, to make the displacement take place over a long period of time, and still have enough stored energy to easily lift the mass. These ideas often required new more complex machines to be added, or our design to be changed entirely.

3 We learned about simple machines, how they work, and what they are capable of doing. Particularly it is very hard to use stored elastic energy with accuracy within certain requirements. For example, initial measurements of the force stored in rubber bands left us to believe our original design would easily lift the mass, however, the force stored in each rubber band differs slightly, and changes due to many factors. Simple machines operate through the usage of stored gravitational energy or kinetic energy. Although they are slightly easier to predict, allow for other complicated issues to arise. Precise measurement of angles, distances are needed shouldn t change because of warped and stretched out materials. For instance, out nylon string, rubber bands, and even wooden boards changed sizes. In retrospect, it seems most of our errors were due to poor planning. To achieve the requirements with accuracy we should have started with the requirements, then calculated how to design the main lifting component around these requirements rather than designing it first and trying to modify it to operate within the constraints given. If we would have tested our materials and ideas individually before trying to synthesize them into a working machine, we would have ensured it operated much better. Finally with this information we should have came up with a design that allowed a small room for error yet still operated within the constraints of the assignment so ensure any unpredictable variables should have been negated.

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