1 12/1/09 Team members: John Bickers Ryan Staggs, and Sean Robinson Team 6 Team name: UReekuh Section C2 EF-151. Windmill of Fortune

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1 1 12/1/09 Team members: John Bickers Ryan Staggs, and Sean Robinson Team 6 Team name: UReekuh Section C2 EF-151 Windmill of Fortune

2 2 Abstract The task for this project was to build a Rube Goldberg contraption that raises a UT banner while exhibiting the physics fundamentals learned in class. Four out of the following seven concepts were required: projectile motion, conservation of translational energy, conservation of momentum, conservation of angular momentum, conservation of rotational energy, torque, and center of mass. In order to maintain a high rate of reliability the device is operated in a simple manner, using as few little parts as possible. Through trial and error and effective decision making, our device works very well and is reliable. The project taught us to use creativity and apply physics concepts learned in class to achieve a goal. Introduction Our objectives were to create a Rube Goldberg device that raises a flag using five unique steps. The device we created demonstrated four different concepts: conservation of energy, conservation of momentum, torque, and rotational energy. It was challenging to incorporate the different concepts while still maintaining functionality. Throughout the process some ideas were discarded and we realized the amount of time trial and error can take up. In the end, however, our device functions very well and neatly. The Design Process We began our project by writing down ideas that we felt would make the contraption complicated but fun to build. These ideas included: marbles, a Nerf gun, a crank, a windmill, a mousetrap car and weights. When we started building, however, we quickly discovered that the Nerf gun would be a bit to complicated to incorporate into the contraption. After tossing the idea of a Nerf gun aside, we also decided to take the crank out as well, mainly because there simply wasn t enough room. We didn t know quite what to expect prior to building the device. The first time we got together we were unorganized and lacked many of the materials we needed to complete the device. After regrouping and making a list of what items we needed, we got together again and successfully built a board with ramps on it which allowed a marble to roll down and trigger the mousetrap car. The plan was to have the marble roll down, trigger the mousetrap car, which in turn triggered the windmill and raised the flag. We decided to use strong rubber bands that would loop around the center of the windmill which would create the needed torque to raise the flag. Once the windmill was fully operational, we

3 3 decided to use a weight and a pulley system to trigger the marble, because there weren t enough steps involved. Through some trial, and a lot of error, we were able to get the device to function properly every time. Device Description Our device starts with a weighted plastic cup that stands on a hollow pipe. A string is attached from the cup up through a whole in a wooden rod, down to a wooden piece hanging below the platform with the marble on top of it. When the cylinder is given a nudge the cup falls down because of potential energy, which creates kinetic energy in the wood hanging on the piece of string. The wood then flies up and hits the platform with the marble on top of it, causing the marble to roll down the three ramps. When the marble gets to the bottom of the last ramp it falls and triggers the mouse trap car. The mousetrap car then hits a plank, which is keeps the windmill from unwinding.

4 4 Due to the conservation of momentum the plank falls and the windmill is free to spin. Once spinning, the windmill raises the flag because of torque and rotational energy. Cost of Materials Used: Nails = 50 cents Screws = $1 Rubber-bands = 75 cents PVC pipe = $2 Wood = $12 Marbles = 50 cents Cardboard = 25 cents K nex = $2 Mousetrap = 30 cents Plastic cup = 20 cents Paper cup = 20 cents Flag = $1 Total = $19.70 Calculations:

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8 8 Results Once completed, the contraption operated smoothly and without trouble. Although the device is reliable there are still some miniscule problems. For example, the device is very sensitive to movement or any force acting on it. This is bad because at the second step the marble is on a flat piece of wood and can easily be bumped so that it prematurely starts. Another problem is the mousetrap. The mousetrap has a tendency to snap shut after locked into place. Besides the little problems the device functions very well and is surprisingly reliable. Conclusions The task was a difficult one; it challenged us to use the concepts taught in class and apply them to real-world circumstances. Not only were we forced to be creative, we also had to be diligent and efficient when working on the device. Through the process we faced different challenges such as: lack of equipment, broken materials, and a hard time trying to cooperate with other teams. In the end, after several hours of hard work and perseverance, we overcame the challenges and made a successful contraption. The only thing that could have been improved better is the falling weight used to start the marble. If the weight hits the base of our device, there is a high chance that the mousetrap could get set off. By using less weight or implementing a stopper, this problem could have been avoided. References: [1] EF-151 website: [2] Notes (for calculations) [3]Past examples of report and presentation: 01/tm/project-gallery.php