EF 151 Project 1 NowGeen Ridley Shetler, Sarah Martin and Chad Dorais Engineering 151 s final project is to create a functioning Rube-Goldberg device that will stamp anywhere on an eight by five sheet of paper. Included in the device must be working examples of conservation of energy, conservation of momentum, and projectile motion. Our particular device, NowGeen, made from recyclable products, incorporates all of these components, as well as a few good examples of center of mass. The beginning process in choosing a design was to watch multiple videos of operating Rube-Goldberg devices to gain an approximate idea of what types of concepts work or do not work. After watching the videos, the brainstorming process brought in plenty of great ideas. We tried our best to include the size restrictions while brainstorming but later found out it had to me much smaller than we had imagined. We also decided to use materials that were recyclable. Once all the ideas that seemed to be worth trying were collected, we began to fit them together into a functioning Rube-Goldberg device. The height, length, and width restrictions were considerably debilitating to our original design. The pinwheel we constructed from an aluminum energy drink can had to stand high enough above the starting point of our car to be able to propel the car down the initial incline. However, this put our project height over the restriction and we had to resort to simply pushing the car down the incline. Also, about half way through our project we had designed two tubes that were carry two balls simultaneously into a cup that would put weight onto a suspending stamp, stamping the sheet of paper. We encountered many problems with this design. What we first noticed was to effectively have the two separate tubes be able to catch each ball and lead
EF 151 Project 2 them into a single cup, we would have to exceed our size restrictions by nearly twice what they were. In addition, having enough force to pull the stamp down on to the paper was a guessing game during each try, and we wanted something more reliable. The finished version of our Rube-Goldberg creation follows a series of activities commencing in stamping a sheet of paper. To begin, a toy dump truck rolls down a tube. As it exits the tube it falls into a box that is perched on one end of a see-saw type contraption. The weight of the dump truck offsets the center of mass raising the opposite end of the see-saw. Connected to the raised end is a pole that raises a platform dumping a ball into a ramp. At the end of the ramp is the bottom of a coke can, mounted on yet another see-saw contraption, acting as a net for the ball. Once the ball is caught the see-saw tips over and the piece of metal attached to it activates a mouse trap. Attached to the mouse trap is the stamp. When the mouse trap is released the stamp snaps down on the opposite side of the mousetrap, stamping a sheet of paper. Initial Proposal
EF 151 Project 3 Final Project We used many recyclable materials that helped us stay within our price budget.
EF 151 Project 4 Conservation of energy is present during each step of our device. All the energy from the car that starts the device is initially potential energy. As the car begins to roll down the tube and into the box on the see-saw, some of that energy is transferred to kinetic energy. Once the ball lands in the box the energy is transferred into the see-saw. As the see-saw rises it causes the tube on the end of the see-saw to collide with the card-board platform creating a conservation of momentum collision. The collision causes a ball positioned on the platform to roll off into a tube, causing another collision. Once the ball is in the tube, it has only potential energy at the moment the initial velocity is zero. As the ball starts to roll down the tube that energy is transferred to kinetic energy. When the ball lands in the aluminum can at the end there is a nearly inelastic collision stopping the ball. The can then allows the popsicle stick connected to it to put pressure on the mouse trap. When triggered the mouse trap has conserved energy that is transferred into kinetic energy with a rotational spring constant. For our particular calculations, we chose a projectile motion, conservation of energy, conservation of momentum, and center of mass calculation. The projectile motion calculation calculates the theoretical initial velocity of the car leaving the tube by using the trajectory formula. Also, as a comparison, we took an actual calculation of the average velocity by dividing the change in position to the change in time. The theoretical velocity was about twice the velocity of the average. The center of mass calculation we conducted produced the theoretical center of mass of the ruler that supports the cardboard box on one side and a small PVC pipe on the other. The theoretical calculation was very close to the actual center of mass that was found when trying to balance it on its stand. We contribute the error to failing to include the mass and distances of the two thumbtacks and the multitude of tape actually used in the contraption.
EF 151 Project 5 Our conservation of energy calculation was used to find the final velocity of the ball when it rolls down the ramp and hits the bottom of the can. Again we calculated a theoretical velocity and an actual average velocity. In this case, the theoretical velocity was much higher than the average. For conservation of energy, we chose to calculate the assumed perfectly elastic collision between the ball and the can to find the final velocities of both. We found that the can actually had a greater final velocity than the ball. We assume this is due to the transfer of kinetic energy from the ball to the can.
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EF 151 Project 8 In the end our project ended up successfully stamping the sheet of paper in a creative, inefficient way! The most important thing we learned through the duration of this project is that it is necessary you be able to adapt to changes, inefficiencies, and failures quickly and productively. While we encountered a number of size issues, as well as some conceptual issues, being able to tackle them in a timely manner allowed us to still come out on top in the end. In reflection, we would have liked to spend more time on the proposal in an effort to be even more creative in the design of our device. We would like to thank you all for a wonderful semester!