In this unit, my group learned everything that goes into building a Rube Goldberg Machine. A Rube Goldberg Machine is an invention or a device that is deliberately complex to complete a simple task. We learned about energy transfers, the six simple machines, and other physics concepts. The six simple machines are a lever, a pulley, a wheel and axle, an inclined plane, a wedge, and a screw. We used three lever systems, one pulley system, one inclined plane, a wedge, and a wheel and axle. The only simple machine we did not use was the screw. In our Rube Goldberg project, our final goal was to create an abstract art piece. Over the course of six weeks, we would plan, build, and present our machines. My group members were Rachel, Collin, Aditya, and Zack. Our project had to include at minimum four different energy transfers, five of the six simple machines, and ten steps. We had only three planning days and nine actual building days. We started our project by thinking of a simple task to complete at the end. We thought about raising a flag or dumping marshmallows in hot chocolate. We decided on making abstract art. I thought this would be too complex, but my group was able to convince me. We then moved on, to thinking about the steps for our projects. To plan our steps, we brainstormed ideas for the actual parts on our machine, that would be creative, but easy. Some of them didn't make the final project, but we were able to make it work. Then, we drew our schematics. This was easy because we didn't have to follow any designs. After those three days, and nine building days, we have The Abstracter. In this Rube Goldberg Machine, we first pull a wedge out of its little crevice. This allows a marble to roll down an 8 inch long inclined plane. The marble falls into a cup, which is attached to a pulley system. The weight marble pulls the first cup down, lifting a second cup. This action pushes the second class lever, making a second marble roll into a tube. At the end of the tube, is a foosball that was larger and heavier than the marble. Assuming that this is a 100% elastic collision, all momentum was transferred from the marble, to the foosball. The foosball is knocked off its platform, dropping five inches onto a first class lever. This pushes a second foosball into a cup, which is attached to a wheel and axle. The weight of the foosball pushes the wheel and the axle starts the next lever. This lever is another second class lever, so it is pushed up to start the marble rolling. The marble rolls into a second tube, knocking over a series of dominoes. These dominoes are pushed over by a toppling effect. The last domino knocks over a cup filled with paint, onto an easel.
Concepts we used in our Rube Goldberg Project
Force - The push or pull on an object that causes change in motion. It is calculated by multiplying mass and acceleration due to gravity (F=ma). We calculated the force of the marble falling into the cup which was .1372N.
Mechanical Advantage - The advantage of force in a machine. -Ideal Mechanical Advantage is calculated by dividing the force load by the force effort (F load/F effort). We found the ideal mechanical advantage of the lever and we got .71MA. -Real Mechanical Advantage is calculated by dividing the distance effort by the distance load (D effort/D load).
Speed - How fast an object moves. It is calculated by dividing distance over time (S=d/t).
Acceleration - The rate of change in speed or velocity. It is calculated by dividing change in velocity over change in time.
Velocity - How fast an object moves in a certain direction. It is calculated by dividing change in distance over change in time. We found the velocity of the ball rolling down the third lever, into the tube, and we found .709m/s.
Potential Energy - Stored energy in an object. It is calculated by multiplying mass, height, and gravity. (PEg=mgh) We calculated the potential energy of the ball at the top of the inclined plane and got .0017 J.
Kinetic Energy - Energy that's already in motion. It is calculated by multiplying mass, velocity squared, and 1/2. (m1/2v^2) We calculated the kinetic energy of the ball rolling down our first lever, and got .003J.
Work - Amount of energy put into something. It is calculated by multiplying force and distance. (W=Fd) We calculated the work of the foosball pushing the wheel and axle, and got .0033J.
Momentum - Tendency of moving objects to keep moving. It is calculated by multiplying mass and velocity. (p=mv)
(All calculations of our project are on pages 2, 3, and 4 of our slideshow presentation.)
In my opinion, I think the end result of The Abstracter was pretty impressive. Building it though, was a hard process. We only had three planning days, and nine actual building days. So of course, we had our peaks, and our pits. Our first peak is that we had five people in our group. Most other groups had only four, so with five people, we decided to split up into two groups. The first group was Rachel, Collin, and myself. The second group was Aditya and Zack. Aditya and Zack mostly worked with the original board, adding steps directly onto it. Rachel, Collin, and I worked on steps further along on the machine, so all we would have to do is attach it. This helped us a lot with planning ahead and seeing problems before they happen. Our first pit was our time management. We couldn't finish our project when the building days were done, so Rachel took the project home and she, Aditya, Collin, and I worked on it over the weekend. Since we still couldn't finish it, we decided to split into our groups again. During class, Aditya and Zack finished the machine, while Rachel and Collin worked on our presentation. I drew our final schematics and made the calculations for our steps. We finished our project the day before presentation night. Phew! Our second peak was how well my group was able to problem solve. On our original schematics, we had plans to knock over a water cup to turn the wheel and axle. We were unable to keep this step in the project because we couldn't get the right amount of water consistently. Too much water and the cut wouldn't tip over, and too little water wouldn't turn the wheel and axle. We replaced the water cup at last minute with a second foosball. Another problem we were able to overcome was in the beginning. We accidentally drilled our first inclined plane on the opposite side of the board. Instead of drilling that piece out, we made our whole Rube Goldberg Machine in the mirror image of our original schematics. My last pit was our communication. Since our group had five people, sometimes it was hard to implement everyone's ideas although I still feel that in the end, everyone was happy with our results. It was also difficult to ensure each person had equal opportunity to explain and describe the different factors of our project without becoming involved in someone else's part of the presentation. Overall though, I think for such a large group, we were able to work well together. My last peak was how well our group worked together. I think we were cohesive mix of personalities and abilities, with a good blend of seriousness and silly. This kept our morale and optimism up, while still getting all our work done. This was a great start to the year, and I'm going to miss this project.