Engineering Fundamentals Final Project Engineering Lab Report 4/26/09 Tony Carr Christopher Goggans Zach Maxey Matt Rhule Team Section A2-6 Engineering Fundamentals 151 I have read and approved of the following report: Tony Carr, Christopher Goggans, Zach Maxey, Matt Rhule 1
Abstract The design challenge was to create an extremely inefficient device, known as a Rube Goldberg machine, capable of turning off an electrical appliance. A speaker system was chosen to be turned off through the activation of a rat trap. Engineering theory and logical thought were used to design the device. Design began at the end with the rat trap and was worked backwards to the beginning, a marble being dropped down a plastic tube. The Rube Goldberg machine performed flawlessly at least eight times in practice, but unfortunately it failed in the demonstration run. Our conclusions from the project were to never make assumptions, and you can never test any design too thoroughly. Introduction The goal for this project was to make a functional Rube Goldberg Device. A Rube Goldberg Device is a device that has different contraptions with in it that are set off by an object, such as a ball, and the contraptions ultimately perform a task, which in our case was to operate an electrical device. To make the Goldberg Device, our group had to use team work skills to come up with a design and as we built our device we had to communicate as engineers with one another to solve problems. In order to make our device work we used different principles we learned in our EF 151 and EF 105 class. Design Process To get our objectives for this project done we first had to form a group that could work together and have members that are reliable. We had been working together in recitation all semester so we decided to work as a team because we could all count on one another to do their part. Next, we met in library and came up with an original blueprint for our design. Each member was accountable for bringing different pieces for our project. We decided to use clear tubing that we found in the Estabrook 13, two five gallon buckets, wood for ramps, hot wheels car and track, and a mouse trap to turn off our speakers. In our original design we had a loop that our hot wheels car would travel on, but after several test runs we had to discard the idea because it did not work consistently. We had to add wooden ramps into our design to extend the overall time of our device. We decided to go with a simple design that worked consistently and met all requirements Device The goal of our Rube-Goldberg project was to turn off a pair of speakers that was playing Rocky Top. The device took many long and strenuous hours to complete. It was fun at times, but at other times it was very frustrating. The first part of our project was a long tube wrapped around two 5 gallon buckets. The buckets were taped one on top of the other. This made the initial height taller than just originally when we had just one bucket. The long tube was connected to two black foam tubes lying across the table. The foam tubes shot the ball out into a series of ramps that we had built on a small piece of plywood. The ramp added a lot of time to the project and gave us more options on what to do towards the end of the project. The ball came off the ramp and collided with a hot wheels car. The hot wheels car was pushed into a launcher that sped up the car with enough speed to get it through the hot wheels track. At the end of the hot wheels track, there was a rat-trap wired to the speakers. The car sets the trap off, which ultimately turns off the speakers. The way it turns off the speakers is that the wires were connected from the speakers to the trap. When the trap snaps, the wires are pulled apart. Our design was a very simple design but sometimes it is hard to predict flaws. 2
Results Our device did not perform as expected. Due to vibrations the car slid out of place and the ball did not collide with it. With a little assistance, the car finished the course and turned off the speakers as planned. Conclusions In conclusion, I believe we had a very successful project. No, it did not work when the money was on the line, but success isn t just how well our device performed. We were also tasked to learn from the project and this was accomplished successfully. Much of what was learned was actually taught outside of class from our interactions with one another. Early in the semester we were all assigned to the same team for our first engineering project; at that point we realized that we worked well together and would be able to cooperate successfully on a much larger project. Engineering projects are designed to give students like ourselves a chance to practice what we learned in a cooperative fashion that emphasizes teamwork. Thankfully our team worked well from the start. We cooperatively planned our initial design and set about constructing our device. Throughout the construction and testing stage we created an atmosphere of security. No one s ideas were ridiculed and each team member meaningfully contributed to each stage. The greatest source of challenge turned out to be the bucket-ball assembly and the wooden ramps. In both cases the ball had a nasty habit of getting lodged or not leaving the tube with enough velocity. To remedy each situation, we reattached the plastic tubing with hot-glue and adjusted the angle on the wooden ramp. Our Achilles heel turned out to be the transition between the ball and the car. On test day, the car vibrated forward and the ball failed to hit it causing the device to fail. In retrospect, we would test our device a little more thoroughly, including testing for unforeseen problems, such as testing for the car sliding out of place. 3
Bill of Materials Appendix References Tony Carr, Christopher Goggans, Zach Maxey, Matt Rhule. (All ideas were conceived and executed by our team. No ideas were borrowed from other sources) Equations Measurements to put into equations Mass Moment of Inertia for ball hh =2.5=.76196 =.05 =.01 =.08 hh =5"=.4167=.12699 =5"=.12699 = 2 5 = 2.05.01 5 =2 10 4
Final velocity of ball at end of tube = 1 2 + 1 2 9.81.76196= 1 2 +.2. =.7 = 3.2678 Projectile motion of ball going out of tube at 90 degree angle Y-direction to find time + + 1 2.12699=0+ 3.2678 + 1 2 9.81 t =.703 X-direction to find distance it travels so we know where to set wooden ramps + + 1 2 0+3.2678.703 Final velocity down last wooden ramp =2.297 = 1 2 + 1 2 9.81.12699=.7 = 1.7798/ Collision of Ball and Hot Wheels Car to find velocity of Hot Wheels Car + = +.05 1.7798 =1.11/ =.08 5