Rube-Goldberg Device The Gnar Machine Team Members Marcus Jeter Tom Cook Issac Sharp Tyson Miller Team Number: 1 EF 151 Section F2
Abstract/Overview: The main purpose of our Rube Goldberg device, The Gnar Machine, is to display an UT banner in an inefficient and complicated fashion. Using all of the allotted dimensions a ball bearing 0.8 meters high is activated by a previous device to set off a chain reaction in order to display a UT banner. The ball bearing falls down a set of inclines thus colliding into a block of wood that is secured to a horizontally rotating wheel. The transfer of energy causes the wheel to start spinning which cause the block of wood to strike a golf ball off of a tee. The golf ball then falls into a cup attached to a pulley wrapped around two skateboard wheels. The mass of the golf ball and cup cause the pulley to move the lever down until gravity overcomes the friction on the wheel and releases it downward. This weight is connected to the bottom of the power T banner, upon hitting the next device the banner is fully displayed. Introduction: According to Webster s New World Dictionary, a Rube Goldberg device is a comically involved, complicated invention, laboriously contrived to perform a simple operation. In our device there are seven steps that each individually display different examples of Conservation of Energy. Although each step displays different concepts, gravity is the key force that causes the device to keep going. To the common eye the device looks fairly simple, but in reality every motion that takes place is a combination of various classifications of physics. The device is viewed as a set of simple reactions and neglect many of the internal forces holding it together. 1
Design and Process: The first day the group met we all wrote down the different types of energy that we could possibly utilize. Of the physics concepts we were allowed to use we decided on using translational energy, rotational energy, linear momentum and center of mass. All of these concepts were fairly easy to achieve. Dropping something with mass would accomplish the translational energy. Anything that involves a spinning wheel achieved out goal of rotational. A simple collision perfectly illustrates linear momentum and the use of a level shows the one of the uses of center of gravity. The Gnar Machine begins with a downward force from the previous teams project which pushes down on a balance beam. The balance beam s opposing side is pushed up, which in turn causes another balance beam to reverse its balance. The balance beam step process begins with the beams in a V shape, and after the two flips between them, they end up in ^ shape. After the balance beams have been flipped the second balance beam releases a ball bearing. This disruption of the balance results in the ball bearing rolling down. The ball bearing then falls into a series of four inclined planes. At the end of the last plane the ball then collides with a vertical plank that is attached to a horizontal wheel. The wheel then rotates and strikes a golf ball that is resting on a tee. The collision causes the cup to fall into a cup attached to a pulley. The gravitation force of the cup attached to the pulley causes the opposite side of the pulley to rotate upward. This upward motion then upsets the balance beam that is holding the weight attached to the banner. The friction that is holding the weight on the balance is then overcame by the force of gravity resulting in the weight falling and unraveling the banner. 2
Bill of Materials: The construction of the Gnar Machine consists of basic wooden configurations, skateboard trucks, and skateboard wheels. All of the materials used were previously available to our group at the lab in Estabrook and at a team member s home garage. The woods used in the machine are: 0.5m x 0.5m plywood, various lengths of a 2 x 4 beam, and small, thin pieces of modeling wood. The skateboard trucks are made of an aluminum alloy, having a base for attachments to the wood, and protruding axles for wheels. The skateboard wheels are all equipped with bearings to help them roll smoothly, as well as fitting them uniformly to the axles of the trucks. An elastic band was used as a belt in the pulley system. Attached to the pulley is a plastic cup. Stainless steel screws, Velcro, and hot glue were used to bond materials. Results of Testing: After the device was built there were only a few problems that had to be dealt with. The ball bearing would often fall off the device between the inclined planes resulting in the whole project not working at all. This was a simple fix though. Extra guard rails were added in between each junction to prevent the ball bearing from falling off the designed path. The next issue that we had with the device was that the ball bearing often times would not hit the vertical plank on the wheel hard enough. This also was an easy fix. We increased the angle of the last inclined plane in order for the ball to hit the plank with more momentum. Other then these two flaws the device worked ideally. 3
Conclusion: Overall the project was successful. Just like most tasks we are given in EF 151 this one was no different, it caused us to be creative thinkers and work out our own problems. There were many times in the creation of the device when we had complete mental blocks and were forced to use our problem solving skills that we have been continually developing throughout the semester. Although the device does not work flawlessly every time it helped with our overall understanding of the Engineering Fundamentals. 4