The GAMM 4.0
December 1, 2009
Morgan McCann, Gabrielle Sobel, Marlene Woodings, Andrea Gingrich
Team Number: 4
EF 151: Section D2
Abstract:
We made a Rube Goldberg device out of household materials and incorporated several energy concepts of physics that we have learned throughout the semester. After multiple drafts we found a design that worked consistently and could be built within the given limitation. By making a smaller model, our project was more efficient and less prone to errors.
Introduction:
A Rube Goldberg project is designed to complete a simple task through many complex steps. Our simple ending task was to drop a banner using steps involving energy transformation. This project allowed us to take what we learned in lecture and apply it in a hands-on method. By doing this we were able to better understand the concepts of torque (rotational motion), conservation of translational energy, projectile motion, and conservation of momentum.
Design Process:
Our first step was to saw a rectangular slab of wood for the base of our project. Then we drilled holes in the wood after measuring the cross section. We then drilled holes into two blocks of wood and glued them to the base. Next, we drilled holes into the sides of these wooden towers in order to stick a pencil through them. We broke tooth picks to make stoppers on either side of the pencil so it could not come out of the towers. To make the rotational motion part of our project we sawed six inches off of a yardstick. We made holes in the middle of the pencil so that the yardstick can rotate about the pencil. We drilled holes and placed screws in the hole in the block of wood to keep the yardstick from falling onto the slab. We added a bolt and a nut to the yardstick and taped a piece of plastic to the top of the bolt so that it would not miss the pvc pipe. We then screwed the dowel into the board. Next we drilled a hole into the top of the dowel and secured the u-clamp with a screw. Using rubber bands, we fastened the pvc pipe to the clamp. Then we drilled another hole into the block and screwed in the angled piece of wood. We screwed in the top of a water bottle and an inch of pvc pipe into the angled block. Next we secured another smaller block of wood onto the slab and placed tape on the wood to reduce friction. We then placed a set mousetrap at the end of the slab. We cut a hole in a plastic cup and stuck a plastic straw through the hole. We then taped a bumper sticker to the straw. Next we cut a coversheet out of printer paper and attached it to the mousetrap with string.Although this draft was not what we had initially designed, it is ultimately what worked. At first we considered other ideas including shooting a marble onto a landing strip for the projectile motion part, unrolling the banner instead of pulling off a cover sheet, and using dominos for translational kinetic energy.
Description of Device:
The materials we used were: a slab of wood, yardstick, pencil, toothpicks, screws, nuts and bolts, dowel, pvc pipe, rubber bands, u-clamp, duct tape, scotch tape, plastic bottle top, plastic cup, string, mouse trap, plastic straw, plastic cup, paper, Tennessee bumper sticker, glue, toy car, ball bearing, extra plastic piece of mousetrap, and printer paper.
In our project we used five different steps to show four of the main concepts we have learned throughout the semester. The first step was the ruler, which pushes the screw into the pvc pipe. This displayed the concept of Torque, or rotational motion. To find the calculations for this we had to know the force of the hands pushing on it and also the radius of the ruler. The second step was the ball bearing rolling down the pvc pipe. This was an example of conservation of translational energy. To find the calculations for this part we had to find the mass of the ball bearing and the height of the pvc pipe. Our next step was a demonstration of projectile motion. The ball bearing was shot into the funnel made by the plastic top. For this step, we calculated the velocity at which the ball bearing was traveling. Our fourth step was collision. This occured when the ball collided with the car, causing an elastic collision. By assuming it was a perfectly elastic collision, we found the velocity of the car at this point. The final step of our project was the car setting off the mousetrap, which pulled a string connected to a cover sheet and displayed our banner.
Results:
The majority of the time, our project successfully completed its task. However, sometimes the screw slipped off the pipe, the ball bearing was not positioned correctly, the car dis not move when hit with the ball, or the mousetrap did not go off. To fix the problem of the screw slipping, we could have used a bigger piece of plastic on top to make sure that it would hit the pipe all the time. The ball bearing problem was difficult to fix. It is hard to balance the ball inside the pipe without it rolling until the pipe had been tilted. However, we figured out that if you move the ball farther down the pipe, it balanced better. The problem with the car not moving seemed fixable by trying out a variety of cars; however, we tried that with no success. It still wasn’t consistent regardless of what car we used. The issue of the mouse trap not going off was a huge factor considering it was related with the task the whole project was supposed to perform. We tried a variety of different mouse traps to see if that made a difference but they all worked about the same for us.
Conclusions:
Our project was successful because it completed the task of displaying a banner. Our last step could also be removed and we were able to connect to the group before and after us. We were able to apply a hands-on method of everything we learned from class this semester. However, the most significant thing we learned from this project was the importance of communication with our peers. It was critical to not only communicate within our group but also with the two groups we had to connect to. Without this our project would not have worked. The main technical problems we had were building the main pieces because ours was on such a small scale, balancing the pipe on the u-clamp with rubber bands, and the excess friction caused by the car and wood. The main thing that we would have fixed if we could have done it differently would have been to replace the step where the ball bearing was balancing in the pvc pipe because this step caused uncertainty each time we performed the demonstration.